@article{AlbrechtHaebelKochetal.2004,
  author    = {Albrecht, Tanja and Haebel, Sophie and Koch, Anke and Krause, Ulrike and Eckermann, Nora and Steup, Martin},
  title     = {Yeast glycogenin (Glg2p) produced in Escherichia coli is simultaneously glucosylated at two vicinal tyrosin residues but results in a reduced bacterial glycogen accumulation},
  year      = {2004},
  abstract  = {Saccharomyces cerevisiae possesses two glycogenin isoforms (designated as Glg1p and Glg2p) that both contain a conserved tyrosine residue, Tyr232. However, Glg2p possesses an additional tyrosine residue, Tyr230 and therefore two potential autoglucosylation sites. Glucosylation of Glg2p was studied using both matrix-assisted laser desorption ionization and electrospray quadrupole time of flight mass spectrometry. Glg2p, carrying a C-terminal (His(6)) tag, was produced in Escherichia coli and purified. By tryptic digestion and reversed phase chromatography a peptide (residues 219-246 of the complete Glg2p sequence) was isolated that contained 4-25 glucosyl residues. Following incubation of Glg2p with UDPglucose, more than 36 glucosyl residues were covalently bound to this peptide. Using a combination of cyanogen bromide cleavage of the protein backbone, enzymatic hydrolysis of glycosidic bonds and reversed phase chromatography, mono- and diglucosylated peptides having the sequence PNYGYQSSPAM were generated. MS/MS spectra revealed that glucosyl residues were attached to both Tyr232 and Tyr230 within the same peptide. The formation of the highly glucosylated eukaryotic Glg2p did not favour the bacterial glycogen accumulation. Under various experimental conditions Glg2p-producing cells accumulated approximately 30\% less glycogen than a control transformed with a Glg2p lacking plasmid. The size distribution of the glycogen and extractable activities of several glycogen-related enzymes were essentially unchanged. As revealed by high performance anion exchange chromatography, the intracellular maltooligosaccharide pattern of the bacterial cells expressing the functional eukaryotic transgene was significantly altered. Thus, the eukaryotic glycogenin appears to be incompatible with the bacterial initiation of glycogen biosynthesis},
  language  = {en}
}
@article{RadingSandmannSteupetal.2015,
  author    = {Rading, M. Michael and Sandmann, Michael and Steup, Martin and Chiarugi, Davide and Valleriani, Angelo},
  title     = {Weak correlation of starch and volume in synchronized photosynthetic cells},
  series = {Physical review : E, Statistical, nonlinear and soft matter physics},
  volume    = {91},
  journal   = {Physical review : E, Statistical, nonlinear and soft matter physics},
  number    = {1},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {1539-3755},
  doi       = {10.1103/PhysRevE.91.012711},
  pages     = {11},
  year      = {2015},
  abstract  = {In cultures of unicellular algae, features of single cells, such as cellular volume and starch content, are thought to be the result of carefully balanced growth and division processes. Single-cell analyses of synchronized photoautotrophic cultures of the unicellular alga Chlamydomonas reinhardtii reveal, however, that the cellular volume and starch content are only weakly correlated. Likewise, other cell parameters, e.g., the chlorophyll content per cell, are only weakly correlated with cell size. We derive the cell size distributions at the beginning of each synchronization cycle considering growth, timing of cell division and daughter cell release, and the uneven division of cell volume. Furthermore, we investigate the link between cell volume growth and starch accumulation. This work presents evidence that, under the experimental conditions of light-dark synchronized cultures, the weak correlation between both cell features is a result of a cumulative process rather than due to asymmetric partition of biomolecules during cell division. This cumulative process necessarily limits cellular similarities within a synchronized cell population.},
  language  = {en}
}
@article{TenenboimSmirnovaWillmitzeretal.2014,
  author    = {Tenenboim, Hezi and Smirnova, Julia and Willmitzer, Lothar and Steup, Martin and Brotman, Yariv},
  title     = {VMP1-deficient Chlamydomonas exhibits severely aberrant cell morphology and disrupted cytokinesies},
  series = {BMC plant biology},
  volume    = {14},
  journal   = {BMC plant biology},
  publisher = {BioMed Central},
  address   = {London},
  issn      = {1471-2229},
  doi       = {10.1186/1471-2229-14-121},
  pages     = {13},
  year      = {2014},
  abstract  = {Background: The versatile Vacuole Membrane Protein 1 (VMP1) has been previously investigated in six species. It has been shown to be essential in macroautophagy, where it takes part in autophagy initiation. In addition, VMP1 has been implicated in organellar biogenesis; endo-, exo- and phagocytosis, and protein secretion; apoptosis; and cell adhesion. These roles underly its proven involvement in pancreatitis, diabetes and cancer in humans. Results: In this study we analyzed a VMP1 homologue from the green alga Chlamydomonas reinhardtii. CrVMP1 knockdown lines showed severe phenotypes, mainly affecting cell division as well as the morphology of cells and organelles. We also provide several pieces of evidence for its involvement in macroautophagy.},
  language  = {en}
}
@article{FettkeLeifelsBrustetal.2012,
  author    = {Fettke, J{\"o}rg and Leifels, Lydia and Brust, Henrike and Herbst, Karoline and Steup, Martin},
  title     = {Two carbon fluxes to reserve starch in potato (Solanum tuberosum L.) tuber cells are closely interconnected but differently modulated by temperature},
  series = {Journal of experimental botany},
  volume    = {63},
  journal   = {Journal of experimental botany},
  number    = {8},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0022-0957},
  doi       = {10.1093/jxb/ers014},
  pages     = {3011 -- 3029},
  year      = {2012},
  abstract  = {Parenchyma cells from tubers of Solanum tuberosum L. convert several externally supplied sugars to starch but the rates vary largely. Conversion of glucose 1-phosphate to starch is exceptionally efficient. In this communication, tuber slices were incubated with either of four solutions containing equimolar [U-C-14]glucose 1-phosphate, [U-C-14]sucrose, [U-C-14]glucose 1-phosphate plus unlabelled equimolar sucrose or [U-C-14]sucrose plus unlabelled equimolar glucose 1-phosphate. C-14-incorporation into starch was monitored. In slices from freshly harvested tubers each unlabelled compound strongly enhanced C-14 incorporation into starch indicating closely interacting paths of starch biosynthesis. However, enhancement disappeared when the tubers were stored. The two paths (and, consequently, the mutual enhancement effect) differ in temperature dependence. At lower temperatures, the glucose 1-phosphate-dependent path is functional, reaching maximal activity at approximately 20 degrees C but the flux of the sucrose-dependent route strongly increases above 20 degrees C. Results are confirmed by in vitro experiments using [U-C-14]glucose 1-phosphate or adenosine-[U-C-14]glucose and by quantitative zymograms of starch synthase or phosphorylase activity. In mutants almost completely lacking the plastidial phosphorylase isozyme(s), the glucose 1-phosphate-dependent path is largely impeded. Irrespective of the size of the granules, glucose 1-phosphate-dependent incorporation per granule surface area is essentially equal. Furthermore, within the granules no preference of distinct glucosyl acceptor sites was detectable. Thus, the path is integrated into the entire granule biosynthesis. In vitro C-14-incorporation into starch granules mediated by the recombinant plastidial phosphorylase isozyme clearly differed from the in situ results. Taken together, the data clearly demonstrate that two closely but flexibly interacting general paths of starch biosynthesis are functional in potato tuber cells.},
  language  = {en}
}
@misc{CencilNitschkeSteupetal.2014,
  author    = {Cencil, Ugo and Nitschke, Felix and Steup, Martin and Minassian, Berge A. and Colleoni, Christophe and Ball, Steven G.},
  title     = {Transition from glycogen to starch metabolism in Archaeplastida},
  series = {Trends in plant science},
  volume    = {19},
  journal   = {Trends in plant science},
  number    = {1},
  publisher = {Elsevier},
  address   = {London},
  issn      = {1360-1385},
  doi       = {10.1016/j.tplants.2013.08.004},
  pages     = {18 -- 28},
  year      = {2014},
  abstract  = {In this opinion article we propose a scenario detailing how two crucial components have evolved simultaneously to ensure the transition of glycogen to starch in the cytosol of the Archaeplastida last common ancestor: (i) the recruitment of an enzyme from intracellular Chlamydiae pathogens to facilitate crystallization of alpha-glucan chains; and (ii) the evolution of novel types of polysaccharide (de)phosphorylating enzymes from preexisting glycogen (de)phosphorylation host pathways to allow the turnover of such crystals. We speculate that the transition to starch benefitted Archaeplastida in three ways: more carbon could be packed into osmotically inert material; the host could resume control of carbon assimilation from the chlamydial pathogen that triggered plastid endosymbiosis; and cyanobacterial photosynthate export could be integrated in the emerging Archaeplastida.},
  language  = {en}
}
@article{HejaziFettkeParisetal.2009,
  author    = {Hejazi, Mahdi and Fettke, J{\"o}rg and Paris, Oskar and Steup, Martin},
  title     = {The two plastidial starch-related dikinases sequentially phosphorylate glucosyl residues at the surface of both the a- and b-type allomorphs of crystallized maltodextrins but the mode of action differs},
  issn      = {0032-0889},
  doi       = {10.1104/pp.109.138750},
  year      = {2009},
  abstract  = {In this study, two crystallized maltodextrins were generated that consist of the same oligoglucan pattern but differ strikingly in the physical order of double helices. As revealed by x-ray diffraction, they represent the highly ordered A- and B-type allomorphs. Both crystallized maltodextrins were similar in size distribution and birefringence. They were used as model substrates to study the consecutive action of the two starch-related dikinases, the glucan, water dikinase and the phosphoglucan, water dikinase. The glucan, water dikinase and the phosphoglucan, water dikinase selectively esterify glucosyl residues in the C6 and C3 positions, respectively. Recombinant glucan, water dikinase phosphorylated both allomorphs with similar rates and caused complete glucan solubilization. Soluble neutral maltodextrins inhibited the glucan, water dikinase-mediated phosphorylation of crystalline particles. Recombinant phosphoglucan, water dikinase phosphorylated both the A- and B-type allomorphs only following a prephosphorylation by the glucan, water dikinase, and the activity increased with the extent of prephosphorylation. The action of the phosphoglucan, water dikinase on the prephosphorylated A- and B-type allomorphs differed. When acting on the B-type allomorph, by far more phosphoglucans were solubilized as compared with the A type. However, with both allomorphs, the phosphoglucan, water dikinase formed significant amounts of mono-phosphorylated phosphoglucans. Thus, the enzyme is capable of acting on neutral maltodextrins. It is concluded that the actual carbohydrate substrate of the phosphoglucan, water dikinase is defined by physical rather than by chemical parameters. A model is proposed that explains, at the molecular level, the consecutive action of the two starch-related dikinases.},
  language  = {en}
}
@article{RitteLloydEckermannetal.2002,
  author    = {Ritte, Gerhard and Lloyd, James R. and Eckermann, Nora and Rottmann, Antje and Kossmann, Jens and Steup, Martin},
  title     = {The starch-related R1 protein is an a-glucan, water dikinase},
  issn      = {0027-8424},
  year      = {2002},
  language  = {en}
}
@inproceedings{EbenhoehKartalSkupinetal.2013,
  author    = {Ebenh{\"o}h, O. and Kartal, Oe. and Skupin, A. and Mahlow, S. and Steup, Martin},
  title     = {The role of mixing entropy in carbohydrate metabolism},
  series = {European biophysics journal : with biophysics letters ; an international journal of biophysics},
  volume    = {42},
  booktitle = {European biophysics journal : with biophysics letters ; an international journal of biophysics},
  publisher = {Springer},
  address   = {New York},
  issn      = {0175-7571},
  pages     = {S73 -- S73},
  year      = {2013},
  language  = {en}
}
@article{HejaziSteupFettke2012,
  author    = {Hejazi, Mahdi and Steup, Martin and Fettke, J{\"o}rg},
  title     = {The plastidial glucan, water dikinase (GWD) catalyses multiple phosphotransfer reactions},
  series = {The FEBS journal},
  volume    = {279},
  journal   = {The FEBS journal},
  number    = {11},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {1742-464X},
  doi       = {10.1111/j.1742-4658.2012.08576.x},
  pages     = {1953 -- 1966},
  year      = {2012},
  abstract  = {The plant genome encodes at least two distinct and evolutionary conserved plastidial starch-related dikinases that phosphorylate a low percentage of glucosyl residues at the starch granule surface. Esterification of starch favours the transition of highly ordered a-glucans to a less ordered state and thereby facilitates the cleavage of interglucose bonds by hydrolases. Metabolically most important is the phosphorylation at position C6, which is catalysed by the glucan, water dikinase (GWD). The reactions mediated by recombinant wild-type GWD from Arabidopsis thaliana (AtGWD) and from Solanum tuberosum (StGWD) were studied. Two mutated proteins lacking the conserved histidine residue that is indispensible for glucan phosphorylation were also included. The wild-type GWDs consume approximately 20\% more ATP than is required for glucan phosphorylation. Similarly, although incapable of phosphorylating a-glucans, the two mutated dikinase proteins are capable of degrading ATP. Thus, consumption of ATP and phosphorylation of a-glucans are not strictly coupled processes but, to some extent, occur as independent phosphotransfer reactions. As revealed by incubation of the GWDs with [gamma-33P]ATP, the consumption of ATP includes the transfer of the gamma-phosphate group to the GWD protein but this autophosphorylation does not require the conserved histidine residue. Thus, the GWD proteins possess two vicinal phosphorylation sites, both of which are transiently phosphorylated. Following autophosphorylation at both sites, native dikinases flexibly use various terminal phosphate acceptors, such as water, alpha-glucans, AMP and ADP. A model is presented describing the complex phosphotransfer reactions of GWDs as affected by the availability of the various acceptors.},
  language  = {en}
}
@article{StahlKlabundeWitzeletal.1994,
  author    = {Stahl, Bernd and Klabunde, Thomas and Witzel, Herbert and Krebs, Bernt and Steup, Martin and Karas, Michael and Hillenkamp, Franz},
  title     = {The oligosaccharides of the Fe(III)-Zn(II) purple acid phosphatase of the red kidney bean : determination of the structure by a combination of matrix-assisted laser desorption-ionization mass spectrometry and selective enzymic degradation},
  year      = {1994},
  language  = {en}
}
@article{HejaziFettkeKoettingetal.2010,
  author    = {Hejazi, Mahdi and Fettke, J{\"o}rg and Koetting, Oliver and Zeeman, Samuel C. and Steup, Martin},
  title     = {The Laforin-like dual-specificity phosphatase SEX4 from Arabidopsis hydrolyzes both C6-and C3-phosphate esters introduced by starch-related dikinases and thereby affects phase transition of alpha-glucans},
  issn      = {0032-0889},
  doi       = {10.1104/pp.109.149914},
  year      = {2010},
  abstract  = {The biochemical function of the Laforin-like dual-specific phosphatase AtSEX4 (EC 3.1.3.48) has been studied. Crystalline maltodextrins representing the A- or the B-type allomorph were prephosphorylated using recombinant glucan, water dikinase (StGWD) or the successive action of both plastidial dikinases (StGWD and AtPWD). AtSEX4 hydrolyzed carbon 6-phosphate esters from both the prephosphorylated A- and B-type allomorphs and the kinetic constants are similar. The phosphatase also acted on prelabeled carbon-3 esters from both crystalline maltodextrins. Similarly, native starch granules prelabeled in either the carbon-6 or carbon-3 position were also dephosphorylated by AtSEX4. The phosphatase did also hydrolyze phosphate esters of both prephosphorylated maltodextrins when the (phospho)glucans had been solubilized by heat treatment. Submillimolar concentrations of nonphosphorylated maltodextrins inhibited AtSEX4 provided they possessed a minimum of length and had been solubilized. As opposed to the soluble phosphomaltodextrins, the AtSEX4- mediated dephosphorylation of the insoluble substrates was incomplete and at least 50\% of the phosphate esters were retained in the pelletable (phospho) glucans. The partial dephosphorylation of the insoluble glucans also strongly reduced the release of nonphosphorylated chains into solution. Presumably, this effect reflects fast structural changes that following dephosphorylation occur near the surface of the maltodextrin particles. A model is proposed defining distinct stages within the phosphorylation/dephosphorylation-dependent transition of alpha-glucans from the insoluble to the soluble state.},
  language  = {en}
}
@article{FettkeEckermannPoesteetal.2004,
  author    = {Fettke, J{\"o}rg and Eckermann, Nora and Poeste, Simon and Steup, Martin},
  title     = {The glycan substrate of the cytosolic (Pho 2) phosphorylase isozyme from Pisum sativum L. : identification, linkage analysis and subcellular localization},
  issn      = {0960-7412},
  year      = {2004},
  abstract  = {The subcellular distribution of starch-related enzymes and the phenotype of Arabidopsis mutants defective in starch degradation suggest that the plastidial starch turnover is linked to a cytosolic glycan metabolism. In this communication, a soluble heteroglycan (SHG) from leaves of Pisum sativum L. has been studied. Major constituents of the SHG are galactose, arabinose and glucose. For subcellular location, the SHG was prepared from isolated protoplasts and chloroplasts. On a chlorophyll basis, protoplasts and chloroplasts yielded approximately 70\% and less than 5\%, respectively, of the amount of the leaf-derived SHG preparation. Thus, most of SHG resides inside the cell but outside the chloroplast. SHG is soluble and not membrane-associated. Using membrane filtration, the SHG was separated into a <10 kDa and a >10 kDa fraction. The latter was resolved into two subfractions (I and II) by field-flow fractionation. In the protoplast-derived >10 kDa SHG preparation the subfraction I was by far the most dominant compound. beta-Glucosyl Yariv reagent was reactive with subfraction II, but not with subfraction I. In in vitro assays the latter acted as glucosyl acceptor for the cytosolic (Pho 2) phosphorylase but not for rabbit muscle phosphorylase. Glycosidic linkage analyses of subfractions I and II and of the Yariv reagent reactive glycans revealed that all three glycans contain a high percentage of arabinogalactan-like linkages. However, SHG possesses a higher content of minor compounds, namely glucosyl, mannosyl, rhamnosyl and fucosyl residues. Based on glycosyl residues and glycosidic linkages, subfraction I possesses a more complex structure than subfraction II},
  language  = {en}
}
@article{YuKoflerHaeusleretal.2001,
  author    = {Yu, Tien-Shin and Kofler, Heike and H{\"a}usler, Rainer E. and Hille, Diana and Fl{\"u}gge, Ulf-Ingo and Zeeman, Samuel C. and Smith, Alison M. and Kossmann, Jens and Lloyd, James R. and Ritte, Gerhard and Steup, Martin and Lue, Wei-Ling and Chen, Jychian and Weber, Andreas P. M.},
  title     = {The Arabidopsis sex1 mutant is defective in the R1 protein, a general regulator of starch degradation in plants, and not in the chloroplast hexose transporter},
  issn      = {1040-4651},
  year      = {2001},
  language  = {en}
}
@article{HemmeVeyelMuehlhausetal.2014,
  author    = {Hemme, Dorothea and Veyel, Daniel and Muehlhaus, Timo and Sommer, Frederik and Jueppner, Jessica and Unger, Ann-Katrin and Sandmann, Michael and Fehrle, Ines and Schoenfelder, Stephanie and Steup, Martin and Geimer, Stefan and Kopka, Joachim and Giavalisco, Patrick and Schroda, Michael},
  title     = {Systems-wide analysis of acclimation responses to long-term heat stress and recovery in the photosynthetic model organism Chlamydomonas reinhardtii},
  series = {The plant cell},
  volume    = {26},
  journal   = {The plant cell},
  number    = {11},
  publisher = {American Society of Plant Physiologists},
  address   = {Rockville},
  issn      = {1040-4651},
  doi       = {10.1105/tpc.114.130997},
  pages     = {4270 -- 4297},
  year      = {2014},
  abstract  = {We applied a top-down systems biology approach to understand how Chlamydomonas reinhardtii acclimates to long-term heat stress (HS) and recovers from it. For this, we shifted cells from 25 to 42 degrees C for 24 h and back to 25 degrees C for >= 8 h and monitored abundances of 1856 proteins/protein groups, 99 polar and 185 lipophilic metabolites, and cytological and photosynthesis parameters. Our data indicate that acclimation of Chlamydomonas to long-term HS consists of a temporally ordered, orchestrated implementation of response elements at various system levels. These comprise (1) cell cycle arrest; (2) catabolism of larger molecules to generate compounds with roles in stress protection; (3) accumulation of molecular chaperones to restore protein homeostasis together with compatible solutes; (4) redirection of photosynthetic energy and reducing power from the Calvin cycle to the de novo synthesis of saturated fatty acids to replace polyunsaturated ones in membrane lipids, which are deposited in lipid bodies; and (5) when sinks for photosynthetic energy and reducing power are depleted, resumption of Calvin cycle activity associated with increased photorespiration, accumulation of reactive oxygen species scavengers, and throttling of linear electron flow by antenna uncoupling. During recovery from HS, cells appear to focus on processes allowing rapid resumption of growth rather than restoring pre-HS conditions.},
  language  = {en}
}
@article{MalinovaSteupFettke2011,
  author    = {Malinova, Irina and Steup, Martin and Fettke, J{\"o}rg},
  title     = {Starch-related cytosolic heteroglycans in roots from Arabidopsis thaliana},
  series = {Journal of plant physiology : biochemistry, physiology, molecular biology and biotechnology of plants},
  volume    = {168},
  journal   = {Journal of plant physiology : biochemistry, physiology, molecular biology and biotechnology of plants},
  number    = {12},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {0176-1617},
  doi       = {10.1016/j.jplph.2010.12.008},
  pages     = {1406 -- 1414},
  year      = {2011},
  abstract  = {Both photoautotrophic and heterotrophic plant cells are capable of accumulating starch inside the plastid. However, depending on the metabolic state of the respective cell the starch-related carbon fluxes are different. The vast majority of the transitory starch biosynthesis relies on the hexose phosphate pools derived from the reductive pentose phosphate cycle and, therefore, is restricted to ongoing photosynthesis. Transitory starch is usually degraded in the subsequent dark period and mainly results in the formation of neutral sugars, such as glucose and maltose, that both are exported into the cytosol. The cytosolic metabolism of the two carbohydrates includes reversible glucosyl transfer reactions to a heteroglycan that are mediated by two glucosyl transferases. DPE2 and PHS2 (or, in all other species, Pho2). In heterotrophic cells, accumulation of starch mostly depends on the long distance transport of reduced carbon compounds from source to sink organs and, therefore, includes as an essential step the import of carbohydrates from the cytosol into the starch forming plastids. In this communication, we focus on starch metabolism in heterotrophic tissues from Arabidopsis thaliana wild type plants (and in various starch-related mutants as well). By using hydroponically grown A. thaliana plants, we were able to analyse starch-related biochemical processes in leaves and roots from the same plants. Within the roots we determined starch levels and the morphology of native starch granules. Cytosolic and apoplastic heteroglycans were analysed in roots and compared with those from leaves of the same plants. A. thaliana mutants lacking functional enzymes either inside the plastid (such as phosphoglucomutase) or in the cytosol (disproportionating isoenzyme 2 or the phosphorylase isozyme, PHS2) were included in this study. In roots and leaves from the three mutants (and from the respective wild type organ as well), starch and heteroglycans as well as enzyme patterns were analysed.},
  language  = {en}
}
@article{EckermannFettkePaulyetal.2004,
  author    = {Eckermann, Nora and Fettke, J{\"o}rg and Pauly, Markus and Bazant, Esther and Steup, Martin},
  title     = {Starch-metabolism related isozymes in higher plants},
  year      = {2004},
  language  = {en}
}
@article{KoettingSanteliaEdneretal.2009,
  author    = {Koetting, Oliver and Santelia, Diana and Edner, Christoph and Eicke, Simona and Marthaler, Tina and Gentry, Matthew S. and Comparot-Moss, Sylviane and Chen, Jychian and Smith, Alison M. and Steup, Martin and Ritte, Gerhard and Zeeman, Samuel C.},
  title     = {STARCH-EXCESS4 is a laforin-like phosphoglucan phosphatase required for starch degradation in Arabidopsis thaliana},
  issn      = {1040-4651},
  doi       = {10.1105/tpc.108.064360},
  year      = {2009},
  abstract  = {Starch is the major storage carbohydrate in plants. It is comprised of glucans that form semicrystalline granules. Glucan phosphorylation is a prerequisite for normal starch breakdown, but phosphoglucan metabolism is not understood. A putative protein phosphatase encoded at the Starch Excess 4 (SEX4) locus of Arabidopsis thaliana was recently shown to be required for normal starch breakdown. Here, we show that SEX4 is a phosphoglucan phosphatase in vivo and define its role within the starch degradation pathway. SEX4 dephosphorylates both the starch granule surface and soluble phosphoglucans in vitro, and sex4 null mutants accumulate phosphorylated intermediates of starch breakdown. These compounds are linear alpha-1,4-glucans esterified with one or two phosphate groups. They are released from starch granules by the glucan hydrolases alpha-amylase and isoamylase. In vitro experiments show that the rate of starch granule degradation is increased upon simultaneous phosphorylation and dephosphorylation of starch. We propose that glucan phosphorylating enzymes and phosphoglucan phosphatases work in synergy with glucan hydrolases to mediate efficient starch catabolism.},
  language  = {en}
}
@article{SchwarteWegnerHavensteinetal.2015,
  author    = {Schwarte, Sandra and Wegner, Fanny and Havenstein, Katja and Groth, Detlef and Steup, Martin and Tiedemann, Ralph},
  title     = {Sequence variation, differential expression, and divergent evolution in starch-related genes among accessions of Arabidopsis thaliana},
  series = {Plant molecular biology : an international journal of fundamental research and genetic engineering},
  volume    = {87},
  journal   = {Plant molecular biology : an international journal of fundamental research and genetic engineering},
  number    = {4-5},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0167-4412},
  doi       = {10.1007/s11103-015-0293-2},
  pages     = {489 -- 519},
  year      = {2015},
  abstract  = {Transitory starch metabolism is a nonlinear and highly regulated process. It originated very early in the evolution of chloroplast-containing cells and is largely based on a mosaic of genes derived from either the eukaryotic host cell or the prokaryotic endosymbiont. Initially located in the cytoplasm, starch metabolism was rewired into plastids in Chloroplastida. Relocation was accompanied by gene duplications that occurred in most starch-related gene families and resulted in subfunctionalization of the respective gene products. Starch-related isozymes were then evolutionary conserved by constraints such as internal starch structure, posttranslational protein import into plastids and interactions with other starch-related proteins. 25 starch-related genes in 26 accessions of Arabidopsis thaliana were sequenced to assess intraspecific diversity, phylogenetic relationships, and modes of selection. Furthermore, sequences derived from additional 80 accessions that are publicly available were analyzed. Diversity varies significantly among the starch-related genes. Starch synthases and phosphorylases exhibit highest nucleotide diversities, while pyrophosphatases and debranching enzymes are most conserved. The gene trees are most compatible with a scenario of extensive recombination, perhaps in a Pleistocene refugium. Most genes are under purifying selection, but disruptive selection was inferred for a few genes/substitutiones. To study transcript levels, leaves were harvested throughout the light period. By quantifying the transcript levels and by analyzing the sequence of the respective accessions, we were able to estimate whether transcript levels are mainly determined by genetic (i.e., accession dependent) or physiological (i.e., time dependent) parameters. We also identified polymorphic sites that putatively affect pattern or the level of transcripts.},
  language  = {en}
}
@article{CisekTokarzSteupetal.2015,
  author    = {Cisek, Richard and Tokarz, Danielle and Steup, Martin and Tetlow, Ian J. and Emes, Michael J. and Hebelstrup, Kim H. and Blennow, Andreas and Barzda, Virginijus},
  title     = {Second harmonic generation microscopy investigation of the crystalline ultrastructure of three barley starch lines affected by hydration},
  series = {Biomedical optics express},
  volume    = {6},
  journal   = {Biomedical optics express},
  number    = {10},
  publisher = {Optical Society of America},
  address   = {Washington},
  issn      = {2156-7085},
  doi       = {10.1364/BOE.6.003694},
  pages     = {3694 -- 3700},
  year      = {2015},
  abstract  = {Second harmonic generation (SHG) microscopy is employed to study changes in crystalline organization due to altered gene expression and hydration in barley starch granules. SHG intensity and susceptibility ratio values (R'(SHG)) are obtained using reduced Stokes-Mueller polarimetric microscopy. The maximum R'(SHG) values occur at moderate moisture indicating the narrowest orientation distribution of nonlinear dipoles from the cylindrical axis of glucan helices. The maximum SHG intensity occurs at the highest moisture and amylopectin content. These results support the hypothesis that SHG is caused by ordered hydrogen and hydroxyl bond networks which increase with hydration of starch granules. (C) 2015 Optical Society of America},
  language  = {en}
}
@article{CisekTokarzKrouglovetal.2014,
  author    = {Cisek, Richard and Tokarz, Danielle and Krouglov, Serguei and Steup, Martin and Emes, Michael J. and Tetlow, Ian J. and Barzda, Virginijus},
  title     = {Second harmonic generation mediated by aligned water in starch granules},
  series = {The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces \& biophysical chemistry},
  volume    = {118},
  journal   = {The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces \& biophysical chemistry},
  number    = {51},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1520-6106},
  doi       = {10.1021/jp508751s},
  pages     = {14785 -- 14794},
  year      = {2014},
  abstract  = {The origin of second harmonic generation (SHG) in starch granules was investigated using ab initio quantum mechanical modeling and experimentally examined using polarization-in, polarization-out (PIPO) second harmonic generation microscopy. Ab initio calculations revealed that the largest contribution to the SHG signal from A- and B-type allomorphs of starch originates from the anisotropic organization of hydroxide and hydrogen bonds mediated by aligned water found in the polymers. The hypothesis was experimentally tested by imaging maize starch granules under various hydration and heat treatment conditions that alter the hydrogen bond network. The highest SHG intensity was found in fully hydrated starch granules, and heat treatment diminished the SHG intensity. The PIPO SHG imaging showed that dried starch granules have a much higher nonlinear optical susceptibility component ratio than fully hydrated granules. In contrast, deuterated starch granules showed a smaller susceptibility component ratio demonstrating that SHG is highly sensitive to the organization of the hydroxyl and hydrogen bond network. The polarization SHG imaging results of potato starch granules, representing starch allomorph B, were compared to those of maize starch granules representing allomorph A. The results showed that the amount of aligned water was higher in the maize granules. Nonlinear microscopy of starch granules provides evidence that varying hydration conditions leads to significant changes in the nonlinear susceptibility ratio as well as the SHG intensity, supporting the hypothesis from ab initio calculations that the dominant contribution to SHG is due to the ordered hydroxide and hydrogen bond network.},
  language  = {en}
}
@article{RitteRuthSteup2000,
  author    = {Ritte, Gerhard and Ruth, Lorberth and Steup, Martin},
  title     = {Reversible binding of the starch-related R1 protein to the surface of transitory starch granules},
  year      = {2000},
  language  = {en}
}
@article{KreftGeorgievaBaeumleretal.2006,
  author    = {Kreft, Oliver and Georgieva, Radostina and B{\"a}umler, Hans and Steup, Martin and M{\"u}ller-R{\"o}ber, Bernd and Sukhorukov, Gleb B. and M{\"o}hwald, Helmuth},
  title     = {Red blood cell templated polyelectrolyte capsules : a novel vehicle for the stable encapsulation of DNA and proteins},
  issn      = {1022-1336},
  doi       = {10.1002/marc.200500777},
  year      = {2006},
  abstract  = {A novel method for the encapsulation of biomacromolecules, such as nucleic acids and proteins, into polyelectrolyte microcapsules is described. Fluorescence-labelled double-stranded DNA and human serum albumin (HSA) are used as model substances for encapsulation in hollow microcapsules templated on human erythrocytes. The encapsulation procedure involves an intermediate drying C, step. The accumulation of DNA and HSA in the capsules is observed by confocal laser scanning microscopy, UV spectroscopy, and flourimetry. The mechanism of encapsulation is discussed},
  language  = {en}
}
@article{Steup2015,
  author    = {Steup, Martin},
  title     = {Raum und Zahl in der Pflanzenphysiologie},
  series = {Raum und Zahl},
  journal   = {Raum und Zahl},
  publisher = {Trafo},
  address   = {Berlin},
  isbn      = {978-3-86464-082-7},
  pages     = {77 -- 109},
  year      = {2015},
  language  = {de}
}
@book{GuentherPetscheFischeretal.2015,
  author    = {G{\"u}nther, Oliver and Petsche, Hans-Joachim and Fischer, Martin H. and Franz, Norbert P. and Steup, Martin and Sixtus, Elena and Heimann, Heinz-Dieter and Pr{\"o}ve, Ralf},
  title     = {Raum und Zahl im Fokus der Wissenschaften},
  series = {Studieren ++ : Konzepte, Perspektiven, Kompetenzen ; 1},
  journal   = {Studieren ++ : Konzepte, Perspektiven, Kompetenzen ; 1},
  editor    = {Petsche, Hans-Joachim},
  publisher = {Trafo},
  address   = {Berlin},
  isbn      = {978-3-86464-082-7},
  pages     = {168},
  year      = {2015},
  abstract  = {Die nun begonnene Reihe „studieren++" resultiert aus einer von der Universit{\"a}t Potsdam angebotenen Vorlesungsreihe. Das Besondere an dieser Vorlesungsreihe ist der multidisziplin{\"a}re Anspruch und die konsequent umgesetzte Zusammenarbeit {\"u}ber Disziplingrenzen hinweg. Die nicht nur {\"u}ber Instituts-, sondern {\"u}ber Fakult{\"a}tsgrenzen praktizierte Interdisziplinarit{\"a}t erlaubt die Betrachtung eines Problems oder Sachverhalts aus unterschiedlichen Blickwinkeln. Wissenschaftliche Fragestellungen sind komplex und nicht immer auf eine Disziplin beschr{\"a}nkt. Sie in ihrer G{\"a}nze erfassen und nachhaltige L{\"o}sungsstrategien oder Konzepte entwickeln zu k{\"o}nnen gelingt oft nur durch eine multidisziplin{\"a}re Kooperation. Eine Lehrveranstaltung wie die vorliegende ist nicht nur f{\"u}r die Studierenden einer Universit{\"a}t eine hervorragende M{\"o}glichkeit, um {\"u}ber die Grenzen der eigenen Disziplin hinaus zu blicken und die Zusammenarbeit mit Wissenschaftlerinnen und Wissenschaftlern aus anderen Bereichen zu pflegen. So lernt man, sich in andere Sichtweisen hineinzuversetzen und sich zwischen den Disziplinen zu bewegen - eine Kompetenz, die in der hochkomplexen Arbeitswelt von heute von hohem Nutzen ist. Der vorliegende erste Band der Reihe hat „Raum und Zahl" zum Thema und ist aus einer Ringvorlesung aus dem Wintersemester 2013/2014 entstanden. Drei der f{\"u}nf Fakult{\"a}ten, insgesamt neun Institute der Universit{\"a}t Potsdam, haben sich an der Vorlesung beteiligt und sich dieses spannenden Themas angenommen. Als jemand, der sich jahrelang wissenschaftlich mit algorithmischer Geometrie sowie mit raumbezogenen Datenbanken und Navigationssystemen besch{\"a}ftigt hat, kann ich nur bekr{\"a}ftigen, dass die Bez{\"u}ge zwischen Raum und Zahl, zwischen R{\"a}umen und Zahlen, noch viel st{\"a}rker im {\"o}ffentlichen Bewusstsein verankert geh{\"o}ren. R{\"a}ume auch quantitativ zu erfassen und zu verstehen ist eine Kulturtechnik, die an Wichtigkeit eher noch zunimmt, vor allem vor dem Hintergrund, dass wir genetisch nicht allzu gut auf derartige Herausforderungen vorbereitet sind. Denn viele unserer einschl{\"a}gigen Gene entstammen noch aus der Zeit der Savanne, einer Zeit, zu der das Raumkonzept sich fast ausschließlich auf die unmittelbare r{\"a}umliche Umgebung bezog und Zahlen jenseits von 10 nur wenig Relevanz f{\"u}r das eigene {\"U}berleben hatten. Als Pr{\"a}sident der Universit{\"a}t Potsdam freut es mich ganz besonders, dass sich die hier vertretenen Wissenschaftler bereit erkl{\"a}rt haben, ihre {\"U}berlegungen mit den Studierenden und ihren Kolleginnen und Kollegen zu teilen. Herrn Kollegen Hans-Joachim Petsche m{\"o}chte ich f{\"u}r sein Engagement danken und ihm zu dieser gelungenen Reihe gratulieren. Der Geist der Wissenschaft, der nicht nur einsam im B{\"u}ro oder Labor gelebt wird, sondern gerade an einer Universit{\"a}t auch aktiv nach außen getragen werden sollte, wird hier in besonderer Weise sichtbar. Ich w{\"u}nsche Ihnen viel Freude bei der Lekt{\"u}re des Bandes und freue mich auf weitere Ver{\"o}ffentlichungen in dieser Reihe.},
  subject      = {Raum},
  language  = {de}
}
@misc{CisekTokarzKontenisetal.2018,
  author    = {Cisek, Richard and Tokarz, Danielle and Kontenis, Lukas and Barzda, Virginijus and Steup, Martin},
  title     = {Polarimetric second harmonic generation microscopy},
  series = {Starch-Starke},
  volume    = {70},
  journal   = {Starch-Starke},
  number    = {1-2},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0038-9056},
  doi       = {10.1002/star.201700031},
  pages     = {15},
  year      = {2018},
  abstract  = {Second harmonic generation (SHG) is a nonlinear optical process that inherently generates signal in non-centrosymmetric materials, such as starch granules, and therefore can be used for label-free imaging. Both intensity and polarization of SHG are determined by material properties that are characterized by the nonlinear susceptibility tensor, ((2)). Examination of the tensor is performed for each focal volume of the image by measuring the outgoing polarization state of the SHG signal for a set of incoming laser beam polarizations. Mapping of nonlinear properties expressed as the susceptibility ratio reveals structural features including the organization of crystalline material within a single starch granule, and the distribution of structural properties in a population of granules. Isolated granules, as well as in situ starch, can be analyzed using polarimetric SHG microscopy. Due to the fast sample preparation and short imaging times, polarimetric SHG microscopy allows for a quick assessment of starch structure and permits rapid feedback for bioengineering applications. This article presents the basics of SHG theory and microscopy applications for starch-containing materials. Quantification of ultrastructural features within individual starch granules is described. New results obtained by polarization resolved SHG microscopy of starch granules are presented for various maize genotypes revealing heterogeneity within a single starch particle and between various granules.},
  language  = {en}
}
@article{AlbrechtKochLodeetal.2001,
  author    = {Albrecht, Tanja and Koch, Anke and Lode, Anja and Greve, Burkhard and Schneider-Mergener, Jens and Steup, Martin},
  title     = {Plastidic (Pho1-type) phosphorylase isoforms in potato (Solanum tuberosum L.) plants : expression analysis and immunochemical characterization},
  year      = {2001},
  language  = {en}
}
@article{DauvilleeChochoisSteupetal.2006,
  author    = {Dauvillee, David and Chochois, Vincent and Steup, Martin and Haebel, Sophie and Eckermann, Nora and Ritte, Gerhard and Ral, Jean-Philippe and Colleoni, Christophe and Hicks, Glenn and Wattebled, Fabrice and Deschamps, Philippe and Lienard, Luc and Cournac, Laurent and Putaux, Jean-Luc and Dupeyre, Danielle and Ball, Steven G.},
  title     = {Plastidial phosphorylase is required for normal starch synthesis in Chlamydomonas reinhardtii},
  series = {The plant journal},
  volume    = {48},
  journal   = {The plant journal},
  number    = {2},
  publisher = {Blackwell},
  address   = {Oxford},
  issn      = {0960-7412},
  doi       = {10.1111/j.1365-313X.2006.02870.x},
  pages     = {274 -- 285},
  year      = {2006},
  abstract  = {Among the three distinct starch phosphorylase activities detected in Chlamydomonas reinhardtii, two distinct plastidial enzymes (PhoA and PhoB) are documented while a single extraplastidial form (PhoC) displays a higher affinity for glycogen as in vascular plants. The two plastidial phosphorylases are shown to function as homodimers containing two 91-kDa (PhoA) subunits and two 110-kDa (PhoB) subunits. Both lack the typical 80-amino-acid insertion found in the higher plant plastidial forms. PhoB is exquisitely sensitive to inhibition by ADP-glucose and has a low affinity for malto-oligosaccharides. PhoA is more similar to the higher plant plastidial phosphorylases: it is moderately sensitive to ADP-glucose inhibition and has a high affinity for unbranched malto-oligosaccharides. Molecular analysis establishes that STA4 encodes PhoB. Chlamydomonas reinhardtii strains carrying mutations at the STA4 locus display a significant decrease in amounts of starch during storage that correlates with the accumulation of abnormally shaped granules containing a modified amylopectin structure and a high amylose content. The wild-type phenotype could be rescued by reintroduction of the cloned wild-type genomic DNA, thereby demonstrating the involvement of phosphorylase in storage starch synthesis.},
  language  = {en}
}
@article{SmirnovaFernieSpahnetal.2017,
  author    = {Smirnova, Julia and Fernie, Alisdair R. and Spahn, Christian M. T. and Steup, Martin},
  title     = {Photometric assay of maltose and maltose-forming enzyme activity by using 4-alpha-glucanotransferase (DPE2) from higher plants},
  series = {Analytical biochemistry : methods in the biological sciences},
  volume    = {532},
  journal   = {Analytical biochemistry : methods in the biological sciences},
  publisher = {Elsevier},
  address   = {San Diego},
  issn      = {0003-2697},
  doi       = {10.1016/j.ab.2017.05.026},
  pages     = {72 -- 82},
  year      = {2017},
  abstract  = {Maltose frequently occurs as intermediate of the central carbon metabolism of prokaryotic and eukaryotic cells. Various mutants possess elevated maltose levels. Maltose exists as two anomers, (alpha- and beta-form) which are rapidly interconverted without requiring enzyme-mediated catalysis. As maltose is often abundant together with other oligoglucans, selective quantification is essential. In this communication, we present a photometric maltose assay using 4-alpha-glucanotransferase (AtDPE2) from Arabidopsis thaliana. Under in vitro conditions, AtDPE2 utilizes maltose as glucosyl donor and glycogen as acceptor releasing the other hexosyl unit as free glucose which is photometrically quantified following enzymatic phosphorylation and oxidation. Under the conditions used, DPE2 does not noticeably react with other di- or oligosaccharides. Selectivity compares favorably with that of maltase frequently used in maltose assays. Reducing end interconversion of the two maltose anomers is in rapid equilibrium and, therefore, the novel assay measures total maltose contents. Furthermore, an AtDPE2-based continuous photometric assay is presented which allows to quantify beta-amylase activity and was found to be superior to a conventional test. Finally, the AtDPE2-based maltose assay was used to quantify leaf maltose contents of both Arabidopsis wild type and AtDPE2-deficient plants throughout the light-dark cycle. These data are presented together with assimilatory starch levels. (C) 2017 Published by Elsevier Inc.},
  language  = {en}
}
@article{RitteScharfEckermannetal.2004,
  author    = {Ritte, Gerhard and Scharf, Anke and Eckermann, Nora and Haebel, Sophie and Steup, Martin},
  title     = {Phosphorylation of transitory starch is increased during degradation},
  year      = {2004},
  abstract  = {The starch excess phenotype of Arabidopsis mutants defective in the starch phosphorylating enzyme glucan, water dikinase (EC 2.7.9.4) indicates that phosphorylation of starch is required for its degradation. However, the underlying mechanism has not yet been elucidated. In this study, two in vivo systems have been established that allow the analysis of phosphorylation of transitory starch during both biosynthesis in the light and degradation in darkness. First, a photoautotrophic culture of the unicellular green alga Chlamydomonas reinhardtii was used to monitor the incorporation of exogenously supplied P-32 orthophosphate into starch. Illuminated cells incorporated P-32 into starch with a constant rate during 2 h. By contrast, starch phosphorylation in darkened cells exceeded that in illuminated cells within the first 30 min, but subsequently phosphate incorporation declined. Pulse-chase experiments performed with P-32/P-31 orthophosphate revealed a high turnover of the starch-bound phosphate esters in darkened cells but no detectable turnover in illuminated cells. Secondly, leaf starch granules were isolated from potato (Solanum tuberosum) plants grown under controlled conditions and glucan chains from the outer granule layer were released by isoamylase. Phosphorylated chains were purified and analyzed using high performance anion-exchange chromatography and matrix-assisted laser desorption/ionization mass spectrometry. Glucans released from the surface of starch granules that had been isolated from darkened leaves possessed a considerably higher degree of phosphorylation than those prepared from leaves harvested during the light period. Thus, in the unicellular alga as well as in potato leaves, net starch degradation is accompanied with an increased phosphorylation of starch},
  language  = {en}
}
@article{RitteHeydenreichMahlowetal.2006,
  author    = {Ritte, Gerhard and Heydenreich, Matthias and Mahlow, Sebastian and Haebel, Sophie and Koetting, Oliver and Steup, Martin},
  title     = {Phosphorylation of C6- and C3-positions of glucosyl residues in starch is catalysed by distinct dikinases},
  series = {FEBS letters : the journal for rapid publication of short reports in molecular biosciences},
  volume    = {580},
  journal   = {FEBS letters : the journal for rapid publication of short reports in molecular biosciences},
  number    = {20},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0014-5793},
  doi       = {10.1016/j.febslet.2006.07.085},
  pages     = {4872 -- 4876},
  year      = {2006},
  abstract  = {Glucan, water dikinase (GWD) and phosphoglucan, water dikinase (PWD) are required for normal starch metabolism. We analysed starch phosphorylation in Arabidopsis wildtype plants and mutants lacking either GWD or PWD using P-31 NMR. Phosphorylation at both C6- and C3-positions of glucose moieties in starch was drastically decreased in GWD-deficient mutants. In starch from PWD-deficient plants C3-bound phosphate was reduced to levels close to the detection limit. The latter result contrasts with previous reports according to which GWD phosphorylates both C6- and C3-positions. In these studies, phosphorylation had been analysed by HPLC of acid-hydrolysed glucans. We now show that maltose-6-phosphate, a product of incomplete starch hydrolysis, co-eluted with glucose-3-phosphate under the chromatographic conditions applied. Re-examination of the specificity of the dikinases using an improved method demonstrates that C6- and C3-phosphorylation is selectively catalysed by GWD and PWD, respectively.},
  language  = {en}
}
@article{StahlThurlZengetal.1994,
  author    = {Stahl, Bernd and Thurl, Stephan and Zeng, Jianru and Karas, Michael and Hillenkamp, Franz and Steup, Martin and Sawatzki, G{\"u}nther},
  title     = {Oligosaccharides from human milk as revealed by matrix-assisted laser desorption : ionization mass spectrometry},
  year      = {1994},
  language  = {en}
}
@article{DeschampsHaferkampDauvilleeetal.2006,
  author    = {Deschamps, Philippe and Haferkamp, Ilka and Dauvillee, David and Haebel, Sophie and Steup, Martin and Buleon, Alain and Putaux, Jean-Luc and Colleoni, Christophe and d'Hulst, Christophe and Plancke, Charlotte and Gould, Sven and Maier, Uwe and Neuhaus, Heinz Eckhard and Ball, Steven G.},
  title     = {Nature of the periplastidial pathway of starch synthesis in the cryptophyte Guillardia theta},
  issn      = {1535-9778},
  doi       = {10.1128/Ec.00380-05},
  year      = {2006},
  abstract  = {The nature of the periplastidial pathway of starch biosynthesis was investigated with the model cryptophyte Guillardia theta. The storage polysaccharide granules were shown to be composed of both amylose and amylopectin fractions with a chain length distribution and crystalline organization very similar to those of starch from green algae and land plants. Most starch granules displayed a shape consistent with biosynthesis occurring around the pyrenoid through the rhodoplast membranes. A protein with significant similarity to the amylose-synthesizing granule-bound starch syntbase 1 from green plants was found as the major polypeptide bound to the polysaccharide matrix. N-terminal sequencing of the mature protein proved that the precursor protein carries a nonfunctional transit peptide in its bipartite topogenic signal sequence which is cleaved without yielding transport of the enzyme across the two inner plastid membranes. The enzyme was shown to display similar affinities for ADP and UDP-glucose, while the V-max measured with UDP-glucose was twofold higher. The granule-bound starch synthase from Guillardia theta was demonstrated to be responsible for the synthesis of long glucan chains and therefore to be the functional equivalent of the amylose- synthesizing enzyme of green plants. Preliminary characterization of the starch pathway suggests that Guillardia theta utilizes a UDP-glucose-based pathway to synthesize starch},
  language  = {en}
}
@article{GrunwaldtHaebelSpitzetal.2002,
  author    = {Grunwaldt, Gisela and Haebel, Sophie and Spitz, Christian and Steup, Martin and Menzel, Ralf},
  title     = {Multiple binding sites of fluorescein isothiocyanate moieties on myoglobin : photophysical heterogeneity as revealed by ground- and excited-state spectroscopy},
  issn      = {1011-1344},
  year      = {2002},
  language  = {en}
}
@article{WernerBehrsingScharteetal.2002,
  author    = {Werner, Deljana and Behrsing, Olaf and Scharte, Gudrun and Woller, Jochen and Steup, Martin and Micheel, Burkhard},
  title     = {Monoclonal anti-diuron antibodies prevent inhibition of photosynthesis by diuron},
  year      = {2002},
  language  = {en}
}
@article{NakamuraSteupColleonietal.2022,
  author    = {Nakamura, Yasunori and Steup, Martin and Colleoni, Christophe and Iglesias, Alberto A. and Bao, Jinsong and Fujita, Naoko and Tetlow, Ian},
  title     = {Molecular regulation of starch metabolism},
  series = {Plant molecular biology : an international journal of fundamental research and genetic engineering},
  volume    = {108},
  journal   = {Plant molecular biology : an international journal of fundamental research and genetic engineering},
  number    = {4-5},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0167-4412},
  doi       = {10.1007/s11103-022-01253-0},
  pages     = {289 -- 290},
  year      = {2022},
  language  = {en}
}
@article{PaparelliGonzaliParlantietal.2012,
  author    = {Paparelli, Eleonora and Gonzali, Silvia and Parlanti, Sandro and Novi, Giacomo and Giorgi, Federico M. and Licausi, Francesco and Kosmacz, Monika and Feil, Regina and Lunn, John Edward and Brust, Henrike and van Dongen, Joost T. and Steup, Martin and Perata, Pierdomenico},
  title     = {Misexpression of a chloroplast aspartyl protease leads to severe growth defects and alters carbohydrate metabolism in arabidopsis},
  series = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants},
  volume    = {160},
  journal   = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants},
  number    = {3},
  publisher = {American Society of Plant Physiologists},
  address   = {Rockville},
  issn      = {0032-0889},
  doi       = {10.1104/pp.112.204016},
  pages     = {1237 -- 1250},
  year      = {2012},
  abstract  = {The crucial role of carbohydrate in plant growth and morphogenesis is widely recognized. In this study, we describe the characterization of nana, a dwarf Arabidopsis (Arabidopsis thaliana) mutant impaired in carbohydrate metabolism. We show that the nana dwarf phenotype was accompanied by altered leaf morphology and a delayed flowering time. Our genetic and molecular data indicate that the mutation in nana is due to a transfer DNA insertion in the promoter region of a gene encoding a chloroplast-located aspartyl protease that alters its pattern of expression. Overexpression of the gene (oxNANA) phenocopies the mutation. Both nana and oxNANA display alterations in carbohydrate content, and the extent of these changes varies depending on growth light intensity. In particular, in low light, soluble sugar levels are lower and do not show the daily fluctuations observed in wild-type plants. Moreover, nana and oxNANA are defective in the expression of some genes implicated in sugar metabolism and photosynthetic light harvesting. Interestingly, some chloroplast-encoded genes as well as genes whose products seem to be involved in retrograde signaling appear to be down-regulated. These findings suggest that the NANA aspartic protease has an important regulatory function in chloroplasts that not only influences photosynthetic carbon metabolism but also plastid and nuclear gene expression.},
  language  = {en}
}
@article{SchwarteBrustSteupetal.2013,
  author    = {Schwarte, Sandra and Brust, Henrike and Steup, Martin and Tiedemann, Ralph},
  title     = {Intraspecific sequence variation and differential expression in starch synthase genes of Arabidopsis thaliana},
  doi       = {10.1186/1756-0500-6-84},
  year      = {2013},
  language  = {en}
}
@article{DuwenigSteupKossmann1997,
  author    = {Duwenig, Elke and Steup, Martin and Kossmann, Jens},
  title     = {Induction of genes encoding plastidic phosphorylase from spinach (Spinacia oleracea L.) and potato (Solanum tuberosum L.) by exogenously supplied carbohydrates in excised leaf discs},
  year      = {1997},
  language  = {en}
}
@article{FettkeEckermannTiessenetal.2005,
  author    = {Fettke, J{\"o}rg and Eckermann, Nora and Tiessen, Axel and Geigenberger, Peter Ludwig and Steup, Martin},
  title     = {Identification, subcellular localization and biochemical characterization of water-soluble heteroglycans (SHG) in leaves of Arabidopsis thaliana L. : distinct SHG reside in the cytosol and in the apoplast},
  issn      = {0960-7412},
  year      = {2005},
  abstract  = {Water-soluble heteroglycans (SHG) were isolated from leaves of wild-type Arabidopsis thaliana L. and from two starch-deficient mutants. Major constituents of the SHG are arabinose, galactose, rhamnose, and glucose. SHG was separated into low (< 10 kDa; SHG(S)) and high (> 10 kDa; SHG(L)) molecular weight compounds. SHG(S) was resolved into approximately 25 distinct oligoglycans by ion exchange chromatography. SHG(L) was further separated into two subfractions, designated as subfraction I and II, by field flow fractionation. For the intracellular localization of the various SHG compounds several approaches were chosen: first, leaf material was subjected to non-aqueous fractionation. The apolar gradient fractions were characterized by monitoring markers and were used as starting material for the SHG isolation. Subfraction I and SHG(S) exhibited a distribution similar to that of cytosolic markers whereas subfraction II cofractionated with crystalline cellulose. Secondly, intact organelles were isolated and used for SHG isolation. Preparations of intact organelles (mitochondria plus peroxisomes) contained no significant amount of any heteroglycan. In isolated intact microsomes a series of oligoglycans was recovered but neither subfraction I nor II. In in vitro assays using glucose 1-phosphate and recombinant cytosolic (Pho 2) phosphorylase both SHG(S) and subfraction I acted as glucosyl acceptor whereas subfraction II was essentially inactive. Rabbit muscle phosphorylase a did not utilize any of the plant glycans indicating a specific Pho 2-glycan interaction. As revealed by in vivo labeling experiments using (CO2)-C-14 carbon fluxes into subfraction I and II differed. Furthermore, in leaves the pool size of subfraction I varied during the light-dark regime},
  language  = {en}
}
@article{EckermannFettkeSteup2002,
  author    = {Eckermann, Nora and Fettke, J{\"o}rg and Steup, Martin},
  title     = {Identification of polysaccharide binding proteins by affinity electrophoresis in inhomogeneous polyacrylamide gels and subsequent SDS-PAGE/MALDI-TOF analysis},
  year      = {2002},
  language  = {en}
}
@article{FettkeNunesNesiFernieetal.2011,
  author    = {Fettke, J{\"o}rg and Nunes-Nesi, Adriano and Fernie, Alisdair R. and Steup, Martin},
  title     = {Identification of a novel heteroglycan-interacting protein, HIP 1.3, from Arabidopsis thaliana},
  series = {Journal of plant physiology : biochemistry, physiology, molecular biology and biotechnology of plants},
  volume    = {168},
  journal   = {Journal of plant physiology : biochemistry, physiology, molecular biology and biotechnology of plants},
  number    = {12},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {0176-1617},
  doi       = {10.1016/j.jplph.2010.09.008},
  pages     = {1415 -- 1425},
  year      = {2011},
  abstract  = {Plastidial degradation of transitory starch yields mainly maltose and glucose. Following the export into the cytosol, maltose acts as donor for a glucosyl transfer to cytosolic heteroglycans as mediated by a cytosolic transglucosidase (DPE2; EC 2.4.1.25) and the second glucosyl residue is liberated as glucose. The cytosolic phosphorylase (Pho2/PHS2; EC 2.4.1.1) also interacts with heteroglycans using the same intramolecular sites as DPE2. Thus, the two glucosyl transferases interconnect the cytosolic pools of glucose and glucose 1-phosphate. Due to the complex monosaccharide pattern, other heteroglycan-interacting proteins (Hips) are expected to exist. Identification of those proteins was approached by using two types of affinity chromatography. Heteroglycans from leaves of Arabidopsis thaliana (Col-0) covalently bound to Sepharose served as ligands that were reacted with a complex mixture of buffer-soluble proteins from Arabidopsis leaves. Binding proteins were eluted by sodium chloride. For identification, SDS-PAGE, tryptic digestion and MALDI-TOF analyses were applied. A strongly interacting polypeptide (approximately 40 kDa; designated as HIP1.3) was observed as product of locus At1g09340. Arabidopsis mutants deficient in HIP1.3 were reduced in growth and contained heteroglycans displaying an altered monosaccharide pattern. Wild type plants express HIP1.3 most strongly in leaves. As revealed by immuno fluorescence, HIP1.3 is located in the cytosol of mesophyll cells but mostly associated with the cytosolic surface of the chloroplast envelope membranes. In an HIP1.3-deficient mutant the immunosignal was undetectable. Metabolic profiles from leaves of this mutant and wild type plants as well were determined by GC-MS. As compared to the wild type control, more than ten metabolites, such as ascorbic acid, fructose, fructose bisphosphate, glucose, glycine, were elevated in darkness but decreased in the light. Although the biochemical function of HIP1.3 has not yet been elucidated, it is likely to possess an important function in the central carbon metabolism of higher plants.},
  language  = {en}
}
@article{KoettingPuschTiessenetal.2005,
  author    = {K{\"o}tting, Oliver and Pusch, Kerstin and Tiessen, Axel and Geigenberger, Peter Ludwig and Steup, Martin and Ritte, Gerhard},
  title     = {Identification of a novel enzyme required for starch metabolism in Arabidopsis leaves : the phosphoglucan, water dikinase},
  year      = {2005},
  abstract  = {The phosphorylation of amylopectin by the glucan, water dikinase (GWD; EC 2.7.9.4) is an essential step within starch metabolism. This is indicated by the starch excess phenotype of GWD-deficient plants, such as the sex1-3 mutant of Arabidopsis (Arabidopsis thaliana). To identify starch-related enzymes that rely on glucan-bound phosphate, we studied the binding of proteins extracted from Arabidopsis wild-type leaves to either phosphorylated or nonphosphorylated starch granules. Granules prepared from the sex1-3 mutant were prephosphorylated in vitro using recombinant potato (Solanum tuberosum) GWD. As a control, the unmodified, phosphate free granules were used. An as-yet uncharacterized protein was identified that preferentially binds to the phosphorylated starch. The C-terminal part of this protein exhibits similarity to that of GWD. The novel protein phosphorylates starch granules, but only following prephosphorylation with GWD. The enzyme transfers the beta-P of ATP to the phosphoglucan, whereas the gamma-P is released as orthophosphate. Therefore, the novel protein is designated as phosphoglucan, water dikinase (PWD). Unlike GWD that phosphorylates preferentially the C6 position of the glucose units, PWD phosphorylates predominantly (or exclusively) the C3 position. Western-blot analysis of protoplast and chloroplast fractions from Arabidopsis leaves reveals a plastidic location of PWD. Binding of PWD to starch granules strongly increases during net starch breakdown. Transgenic Arabidopsis plants in which the expression of PWD was reduced by either RNAi or a T-DNA insertion exhibit a starch excess phenotype. Thus, in Arabidopsis leaves starch turnover requires a close collaboration of PWD and GWD},
  language  = {en}
}
@article{NitschkeWangSchmiederetal.2013,
  author    = {Nitschke, Felix and Wang, Peixiang and Schmieder, Peter and Girard, Jean-Marie and Awrey, Donald E. and Wang, Tony and Israelian, Johan and Zhao, XiaoChu and Turnbull, Julie and Heydenreich, Matthias and Kleinpeter, Erich and Steup, Martin and Minassian, Berge A.},
  title     = {Hyperphosphorylation of glucosyl C6 carbons and altered structure of glycogen in the neurodegenerative epilepsy lafora disease},
  series = {Cell metabolism},
  volume    = {17},
  journal   = {Cell metabolism},
  number    = {5},
  publisher = {Cell Press},
  address   = {Cambridge},
  issn      = {1550-4131},
  doi       = {10.1016/j.cmet.2013.04.006},
  pages     = {756 -- 767},
  year      = {2013},
  abstract  = {Laforin or malin deficiency causes Lafora disease, characterized by altered glycogen metabolism and teenage-onset neurodegeneration with intractable and invariably fatal epilepsy. Plant starches possess small amounts of metabolically essential monophosphate esters. Glycogen contains similar phosphate amounts, which are thought to originate from a glycogen synthase error side reaction and therefore lack any specific function. Glycogen is also believed to lack monophosphates at glucosyl carbon C6, an essential phosphorylation site in plant starch metabolism. We now show that glycogen phosphorylation is not due to a glycogen synthase side reaction, that C6 is a major glycogen phosphorylation site, and that C6 monophosphates predominate near centers of glycogen molecules and positively correlate with glycogen chain lengths. Laforin or malin deficiency causes C6 hyperphosphorylation, which results in malformed long-chained glycogen that accumulates in many tissues, causing neurodegeneration in brain. Our work advances the understanding of Lafora disease pathogenesis and suggests that glycogen phosphorylation has important metabolic function.},
  language  = {en}
}
@article{AlbrechtGrevePuschetal.1998,
  author    = {Albrecht, Tanja and Greve, Burkhard and Pusch, Kerstin and Koßmann, Jens and Buchner, Peter and Wobus, Ulrich and Steup, Martin},
  title     = {Homo- and Heterodimers of Pho1-Type Phosphorylase Isoforms in Solanum tuberosum L. as Revealed by Sequence- Specific Antibodies},
  year      = {1998},
  language  = {en}
}
@article{FettkeMalinovaAlbrechtetal.2011,
  author    = {Fettke, J{\"o}rg and Malinova, Irina and Albrecht, Tanja and Hejazi, Mahdi and Steup, Martin},
  title     = {Glucose-1-Phosphate transport into protoplasts and chloroplasts from leaves of arabidopsis},
  series = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants},
  volume    = {155},
  journal   = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants},
  number    = {4},
  publisher = {American Society of Plant Physiologists},
  address   = {Rockville},
  issn      = {0032-0889},
  doi       = {10.1104/pp.110.168716},
  pages     = {1723 -- 1734},
  year      = {2011},
  abstract  = {Almost all glucosyl transfer reactions rely on glucose-1-phosphate (Glc-1-P) that either immediately acts as glucosyl donor or as substrate for the synthesis of the more widely used Glc dinucleotides, ADPglucose or UDPglucose. In this communication, we have analyzed two Glc-1-P-related processes: the carbon flux from externally supplied Glc-1-P to starch by either mesophyll protoplasts or intact chloroplasts from Arabidopsis (Arabidopsis thaliana). When intact protoplasts or chloroplasts are incubated with [U-C-14]Glc-1-P, starch is rapidly labeled. Incorporation into starch is unaffected by the addition of unlabeled Glc-6-P or Glc, indicating a selective flux from Glc-1-P to starch. However, illuminated protoplasts incorporate less C-14 into starch when unlabeled bicarbonate is supplied in addition to the C-14-labeled Glc-1-P. Mesophyll protoplasts incubated with [U-C-14] Glc-1-P incorporate C-14 into the plastidial pool of adenosine diphosphoglucose. Protoplasts prepared from leaves of mutants of Arabidopsis that lack either the plastidial phosphorylase or the phosphoglucomutase isozyme incorporate C-14 derived from external Glc-1-P into starch, but incorporation into starch is insignificant when protoplasts from a mutant possessing a highly reduced ADPglucose pyrophosphorylase activity are studied. Thus, the path of assimilatory starch biosynthesis initiated by extraplastidial Glc-1-P leads to the plastidial pool of adenosine diphosphoglucose, and at this intermediate it is fused with the Calvin cycle-driven route. Mutants lacking the plastidial phosphoglucomutase contain a small yet significant amount of transitory starch.},
  language  = {en}
}
@article{FettkeAlbrechtHejazietal.2010,
  author    = {Fettke, J{\"o}rg and Albrecht, Tanja and Hejazi, Mahdi and Mahlow, Sebastian and Nakamura, Yasunori and Steup, Martin},
  title     = {Glucose 1-phosphate is efficiently taken up by potato (Solanum tuberosum) tuber parenchyma cells and converted to reserve starch granules},
  issn      = {0028-646X},
  doi       = {10.1111/j.1469-8137.2009.03126.x},
  year      = {2010},
  abstract  = {Reserve starch is an important plant product but the actual biosynthetic process is not yet fully understood. Potato (Solanum tuberosum) tuber discs from various transgenic plants were used to analyse the conversion of external sugars or sugar derivatives to starch. By using in vitro assays, a direct glucosyl transfer from glucose 1-phosphate to native starch granules as mediated by recombinant plastidial phosphorylase was analysed. Compared with labelled glucose, glucose 6-phosphate or sucrose, tuber discs converted externally supplied [C-14] glucose 1-phosphate into starch at a much higher rate. Likewise, tuber discs from transgenic lines with a strongly reduced expression of cytosolic phosphoglucomutase, phosphorylase or transglucosidase converted glucose 1-phosphate to starch with the same or even an increased rate compared with the wild-type. Similar results were obtained with transgenic potato lines possessing a strongly reduced activity of both the cytosolic and the plastidial phosphoglucomutase. Starch labelling was, however, significantly diminished in transgenic lines, with a reduced concentration of the plastidial phosphorylase isozymes. Two distinct paths of reserve starch biosynthesis are proposed that explain, at a biochemical level, the phenotype of several transgenic plant lines.},
  language  = {en}
}
@article{NakamuraOnoUtsumietal.2012,
  author    = {Nakamura, Yasunori and Ono, Masami and Utsumi, Chikako and Steup, Martin},
  title     = {Functional interaction between plastidial starch phosphorylase and starch branching enzymes from rice during the synthesis of branched maltodextrins},
  series = {Plant \& cell physiology},
  volume    = {53},
  journal   = {Plant \& cell physiology},
  number    = {5},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0032-0781},
  doi       = {10.1093/pcp/pcs030},
  pages     = {869 -- 878},
  year      = {2012},
  abstract  = {The present study established the way in which plastidial alpha-glucan phosphorylase (Pho1) synthesizes maltodextrin (MD) which can be the primer for starch biosynthesis in rice endosperm. The synthesis of MD by Pho1 was markedly accelerated by branching enzyme (BE) isozymes, although the greatest effect was exhibited by the presence of branching isozyme I (BEI) rather than by isozyme IIa (BEIIa) or isozyme IIb (BEIIb). The enhancement of the activity of Pho1 by BE was not merely due to the supply of a non-reducing ends. At the same time, Pho1 greatly enhanced the BE activity, possibly by generating a branched carbohydrate substrate which is used by BE with a higher affinity. The addition of isoamylase to the reaction mixture did not prevent the concerted action of Pho1 and BEI. Furthermore, in the product, the branched structure was, at least to some extent, maintained. Based on these results we propose that the interaction between Pho1 and BE is not merely due to chain-elongating and chain-branching reactions, but occurs in a physically and catalytically synergistic manner by each activating the mutual capacity of the other, presumably forming a physical association of Pho1, BEI and branched MDs. This close interaction might play a crucial role in the synthesis of branched MDs and the branched MDs can act as a primer for the biosynthesis of amylopectin molecules.},
  language  = {en}
}
@article{MartinsHejaziFettkeetal.2013,
  author    = {Martins, Marina Camara Mattos and Hejazi, Mahdi and Fettke, J{\"o}rg and Steup, Martin and Feil, Regina and Krause, Ursula and Arrivault, Stephanie and Vosloh, Daniel and Figueroa, Carlos Maria and Ivakov, Alexander and Yadav, Umesh Prasad and Piques, Maria and Metzner, Daniela and Stitt, Mark and Lunn, John Edward},
  title     = {Feedback inhibition of starch degradation in arabidopsis leaves mediated by trehalose 6-phosphate},
  series = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants},
  volume    = {163},
  journal   = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants},
  number    = {3},
  publisher = {American Society of Plant Physiologists},
  address   = {Rockville},
  issn      = {0032-0889},
  doi       = {10.1104/pp.113.226787},
  pages     = {1142 -- 1163},
  year      = {2013},
  abstract  = {Many plants accumulate substantial starch reserves in their leaves during the day and remobilize them at night to provide carbon and energy for maintenance and growth. In this paper, we explore the role of a sugar-signaling metabolite, trehalose-6-phosphate (Tre6P), in regulating the accumulation and turnover of transitory starch in Arabidopsis (Arabidopsis thaliana) leaves. Ethanol-induced overexpression of trehalose-phosphate synthase during the day increased Tre6P levels up to 11-fold. There was a transient increase in the rate of starch accumulation in the middle of the day, but this was not linked to reductive activation of ADP-glucose pyrophosphorylase. A 2- to 3-fold increase in Tre6P during the night led to significant inhibition of starch degradation. Maltose and maltotriose did not accumulate, suggesting that Tre6P affects an early step in the pathway of starch degradation in the chloroplasts. Starch granules isolated from induced plants had a higher orthophosphate content than granules from noninduced control plants, consistent either with disruption of the phosphorylation-dephosphorylation cycle that is essential for efficient starch breakdown or with inhibition of starch hydrolysis by beta-amylase. Nonaqueous fractionation of leaves showed that Tre6P is predominantly located in the cytosol, with estimated in vivo Tre6P concentrations of 4 to 7 mu M in the cytosol, 0.2 to 0.5 mu M in the chloroplasts, and 0.05 mu M in the vacuole. It is proposed that Tre6P is a component in a signaling pathway that mediates the feedback regulation of starch breakdown by sucrose, potentially linking starch turnover to demand for sucrose by growing sink organs at night.},
  language  = {en}
}
@article{FettkeHejaziSmirnovaetal.2009,
  author    = {Fettke, J{\"o}rg and Hejazi, Mahdi and Smirnova, Julia and Hoechel, Erik and Stage, Marion and Steup, Martin},
  title     = {Eukaryotic starch degradation : integration of plastidial and cytosolic pathways},
  issn      = {0022-0957},
  doi       = {10.1093/Jxb/Erp054},
  year      = {2009},
  abstract  = {Starch is an important plant product widely used as a nutrient, as a source of renewable energy, and for many technological applications. In plants, starch is the almost ubiquitous storage carbohydrate whereas most heterotrophic prokaryotes and eukaryotes rely on glycogen. Despite close similarities in basic chemical features, starch and glycogen differ in both structural and physicochemical properties. Glycogen is a hydrosoluble macromolecule with evenly distributed branching points. Starch exists as a water-insoluble particle having a defined (and evolutionary conserved) internal structure. The biochemistry of starch requires the co-operation of up to 40 distinct (iso)enzymes whilst approximately 10 (iso)enzymes permit glycogen metabolism. The biosynthesis and degradation of native starch include the transition of carbohydrates from the soluble to the solid phase and vice versa. In this review, two novel aspects of the eukaryotic plastidial starch degradation are discussed: Firstly, biochemical reactions that take place at the surface of particulate glucans and mediate the phase transition of carbohydrates. Secondly, processes that occur downstream of the export of starch-derived sugars into the cytosol. Degradation of transitory starch mainly results in the formation of neutral sugars, such as glucose and maltose, that are transported into the cytosol via the respective translocators. The cytosolic metabolism of the neutral sugars includes the action of a hexokinase, a phosphoglucomutase, and a transglucosidase that utilizes high molecular weight glycans as a transient glucosyl acceptor or donor. Data are included on the transglucosidase (disproportionating isozyme 2) in Cyanophora paradoxa that accumulates storage carbohydrates in the cytosol rather than in the plastid.},
  language  = {en}
}
@article{HaebelAlbrechtSparbieretal.1998,
  author    = {Haebel, Sophie and Albrecht, Tanja and Sparbier, Katrin and Walden, Peter and K{\"o}rner, Roman and Steup, Martin},
  title     = {Electrophoresis-related protein modification: alkylation of carboxy residues revealed by mass spectrometry},
  year      = {1998},
  language  = {en}
}