TY  - JOUR
A1  - Stalz, Holger
A1  - Roth, Udo
A1  - Schleuder, Detlev
A1  - Macht, Marcus
A1  - Haebel, Sophie
A1  - Strupat, Kerstin
A1  - Peter-Katalinic, Jasna
A1  - Hanisch, Franz-Georg
T1  - The Geodia cydonium galectin exhibits prototype and chimera-type characteristics and a unique sequence polymorphism within its carbohydrate recognition domain
N2  - The ancestral galectin from the sponge Geodia cydonium (GCG) is classified on a structural basis to the prototype subfamily, whereas its carbohydrate-binding specificity is related to that of the mammalian chimera-type galectin-3. This dual coordination reveals GCG as a potential precursor of the later evolved galectin subfamilies, which is reflected in the primary structure of the protein. This study provides evidence that GCG is the LECT1 gene product, while neither a previously described LECT2 gene nor a functional LECT2 gene product was found in the specimen under investigation. The electrophoretically separated protein isomers with apparent molecular masses of 13, 15, and 16 kDa correspond to variants of the LECT1 protein-exhibiting peptide sequence polymorphisms that concern critical positions of the carbohydrate recognition domain (13 kDa: Leu51, Asn55, His130, Gly137; 15 kDa: Ser51, Asn55, Asn130, Gly137; 16 kDa: Ser51, Tyr55, Asn130, Glu137). Four residues, highly conserved in the galectin family, are substituted. None of the residues claimed to be involved in interactions with GalNAc alpha 1-3 moieties at an extended binding subsite of galectin-3 was identified in the corresponding positions of GCG. Apparently, the substitutions do not confer distinct binding characteristics to the GCG variants as evidenced by binding studies with a recombinantly expressed 15-kDa isoform. The natural isoforms as well as the recombinant 15-kDa isoform oligomerize by the formation of non-covalent heteromeric or homomeric complexes. A phosphorylation of the galectin was confirmed neither by mass spectrometry nor by alkaline phosphatase treatment combined with isoelectric focusing
Y1  - 2006
UR  - http://glycob.oxfordjournals.org/content/16/5/402.full
U6  - https://doi.org/10.1093/glycob/cwj086
ER  - 
TY  - JOUR
A1  - Strehmel, Veronika
A1  - Sarker, A. M.
A1  - Lahti, P. M.
A1  - Karasz, F. E.
A1  - Heydenreich, Matthias
A1  - Wetzel, Hendrik
A1  - Haebel, Sophie
A1  - Strehmel, Bernd
T1  - One- and two-photon photochemistry and photophysics of poly(arylenevinylene)s containing a biphenyl moiety
N2  - Photochemical and photophysical properties were investigated for poly(arylenevinylene)s containing a flexible biphenyl "hinge" unit by applying one-photon (OP) and two-photon (TP) excitation to explore excited-state properties. The poly(arylenevinylene)s were poly[(2,5-dihexyloxy-p-phenylenevinylene)-alt-(4,4'-dihexyloxy-3,3'-biph enylenevinylene)] (1), poly[(2,5-dihexyloxy-p-phenylenevinylene)-alt-(2,2'-dihexyloxy-3,3'-biph enylenevinylene)] (2), and poly[(2,5-dihexyloxy-p-phenylenevinylene)-alt-(2,2'-biphenylene-vinylene )] (3). Effective emission quantum yields and related photonic properties were evaluated on a realistic per-chromophore basis using effective conjugation lengths based on the Strickler-Berg relationship. intramolecular photocyclization was deduced to occur in the one case where the biphenyl molecular connectivity permitted the reaction, based on matrix- assisted loser desorption/ionization time-of-flight (MALDI-TOF), heteronuclear multiple-quantum coherence (HMQC)-NMR, and gel-permeation chromatography (GPC) results. The various photoprocesses could be induced by either OP or TP excitation, though the first excited singlet state is the photoactive state. The higher excitation energy 1 of the TP excited state favors indirect population of the S, state by electronic coupling between the TP and OP excited states [lambda(max)(TPE) (nm): 726; delta (GM)([9]): 1 = 229, 2 = 215, 3 = 109). Photochemical processes occurring from the lowest OP excited state (S-1) could therefore also be indirectly induced by TP excitation
Y1  - 2005
SN  - 1439-4235
ER  - 
TY  - JOUR
A1  - Gericke, Beate
A1  - Raila, Jens
A1  - Sehouli, Jalid
A1  - Haebel, Sophie
A1  - Konsgen, D.
A1  - Mustea, A.
A1  - Schweigert, Florian J.
T1  - Microheterogeneity of transthyretin in serum and ascitic fluid of ovarian cancer patients
N2  - Background: Transthyretin (TTR), a traditional biomarker for nutritional and inflammatory status exists in different molecular variants of yet unknown importance. A truncated form of TTR has recently been described to be part of a set of biomarkers for the diagnosis of ovarian cancer. The main aim of the study was therefore to characterize differences in microheterogeneity between ascitic fluid and plasma of women affected with ovarian cancer and to evaluate the tumor site as the possible source of TTR. Methods: Subjects were 48 women with primary invasive epithelial ovarian cancer or recurrent ovarian carcinoma. The control group consisted of 20 postmenopausal women. TTR and retinol-binding protein (RBP) levels were measured by enzyme-linked immunoassay ( ELISA) and C-reactive protein (CRP) levels by a high- sensitivity latex particle turbidimetric assay. The molecular heterogeneity of TTR was analysed using immunoprecipitation and matrix-associated laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Presence of TTR in tumor tissue was determined with indirect peroxidase immunostaining. Results: TTR and RBP (mu g/ml) levels in serum were 148.5 +/- 96.7 and 22.5 +/- 14.8 in affected women compared to 363.3 +/- 105.5 and 55.8 +/- 9.3 in healthy postmenopausal women ( p < 0.01). In ascitic fluid, levels were 1.02 +/- 0.24 and 4.63 +/- 1.57 mu g/ml, respectively. The mean levels of TTR and RBP in serum showed a tendency to decrease with the severity of the disease and were lower in affected women whose CRP levels were > 40 mg/ml ( p = 0.08 for TTR; p < 0.05 for RBP). No differences in TTR microheterogeneity were observed between TTR isolated from serum of affected and healthy women or from ascitic fluid. TTR occurred rather consistently in four variants. Mass signals were at 13758 +/- 7, 13876 +/- 13 ( greatest intensity), 13924 +/- 21 and 14062 +/- 24 Da, representing native, S-cysteinylated, S-cysteinglycinylated and glutathionylated TTR, respectively. Serum of healthy and affected women as well as ascitic fluid contained the truncated fragment of TTR ( 12828 +/- 11 Da). No immunoreactive TTR was observed in the tumor sites. Conclusion: The severity of the cancer associated catabolism as well as the inflammation status affect serum TTR and RBP levels. Neither TTR nor its truncated form originates from tumor tissue and its occurrence in ascites may well reflect the filtration from blood into ascitic fluid
Y1  - 2005
SN  - 1471-2407
ER  - 
TY  - JOUR
A1  - Xie, J.
A1  - Techritz, S.
A1  - Haebel, Sophie
A1  - Horn, A.
A1  - Neitzel, H.
A1  - Klose, J.
A1  - Schuelke, M.
T1  - A two-dimensional electrophoretic map of human mitochondrial proteins from immortalized lymphoblastoid cell lines: a prerequisite to study mitochondrial disorders in patients
N2  - Mitochondrial diseases may be caused by numerous mutations that alter proteins of the respiratory chain and of other metabolic pathways in the mitochondrium. For clinicians this disease group poses a considerable diagnostic challenge due to ambiguous genotype-phenotype relationships. Until now, only 30 % of the mitochondriopathies can be diagnosed at the molecular level. We therefore need a new diagnostic tool that offers a wide view on the mitochondrial proteins. Here, we present a method to generate a high-resolution, large-gel two-dimensional gel electrophoretic (2-DE) map of a purified fraction of mitochondrial proteins from Epstein-Barr virus-immortalized lymphoblastoid cell line (LCL). LCLs can be easily obtained from patients and control subjects in a routine clinical setting. They often express the biochemical phenotype and can be cultured to high cell numbers, sufficient to gain enough purified material for 2- DE. In total we identified 166 mitochondrial proteins. Thirteen proteins were earlier not known to be of mitochondrial origin. Thirty-nine proteins were associated with human diseases ranging from respiratory chain enzyme deficiencies to disorders of P-oxidation and amino acid metabolism. This 2-DE map is intended to be the first step to diagnose mitochondrial diseases at the proteomic level
Y1  - 2005
SN  - 1615-9853
ER  - 
TY  - JOUR
A1  - Bahrke, Sven
A1  - Einarsson, Jon M.
A1  - Gislason, Johannes
A1  - Haebel, Sophie
A1  - Peter-Katalinic, Jasna
T1  - Characterization of chitooligosaccharides by mass spectrometry
N2  - Heterochitooligosaccharides of DP 6, DP 9, and DP 12 were evaluated using established methods of derivatization and matrix-assisted laser desorption ionization post source decay mass spectrometry.
Y1  - 2003
SN  - 82-471-5901-5
ER  - 
TY  - THES
A1  - Bahrke, Sven
A1  - Einarsson, Jon M.
A1  - Gislason, Johannes
A1  - Haebel, Sophie
A1  - Peter-Katalinic, Jasna
A1  - Peter, Martin G.
T1  - Characterization of chitooligosaccharides by mass spectrometry
Y1  - 2003
SN  - 82-47-15901-5
ER  - 
TY  - JOUR
A1  - Rawel, Harshadrai Manilal
A1  - Kroll, Jürgen
A1  - Riese-Schneider, Brigitte
A1  - Haebel, Sophie
T1  - Changes in physico-chemical and enzymatic properties of benzyl isothiocyanate derivatized proteinases
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Haebel, Sophie
A1  - Peter-Katalinic, Jasna
A1  - Peter, Martin G.
T1  - Mass spectrometry of chitooligosaccharides
Y1  - 1997
SN  - 88-86889- 01-1
ER  - 
TY  - JOUR
A1  - Asgeirsson, Bjarni
A1  - Haebel, Sophie
A1  - Thorsteinsson, Leifur
A1  - Helgason, Erlendur
A1  - Gudmundsson, Kristbjörn O.
A1  - Gudmundsson, Gunnar
A1  - Roepstorff, Peter
T1  - Hereditary cystatin C amyloid angiopathy: monitoring the presence of the Leu-68 -> Gln cystatin C variant in cerebrospinal fluids and monocyte cultures by MS
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Gehmlich, Katja
A1  - Hayess, Katrin
A1  - Legler, Christof
A1  - Haebel, Sophie
A1  - van der Ven, Peter F. M.
A1  - Ehler, Elisabeth
A1  - Fuerst, Dieter O.
T1  - Ponsin interacts with Nck adapter proteins : implications for a role in cytoskeletal remodelling during differentiation of skeletal muscle cells
N2  - Skeletal muscle differentiation is a complex process: It is characterised by changes in gene expression and protein composition. Simultaneously, a dramatic remodelling of the cytoskeleton and associated cell-matrix contacts, the costameres, occurs. The expression and localisation of the protein ponsin at cell-matrix contacts marks the establishment of costameres. In this report we show that skeletal muscle cells are characterised by a novel ponsin isoform, which contains a large insertion in its carboxy-terminus. This skeletal muscle-specific module binds the adapter proteins Nck1 and Nck2, and increased co-localisation of ponsin with Nck2 is observed at remodelling cell-matrix contacts of differentiating skeletal muscle cells. Since this ponsin insertion can be phosphorylated, it may adjust the interaction affinity with Nck adapter proteins. The novel ponsin isoform and its interaction with Nck1/2 provide exciting insight into the convergence of signalling pathways at the costameres, and its crucial role for skeletal muscle differentiation and re-generation.
Y1  - 2010
UR  - http://www.sciencedirect.com/science/journal/01719335
U6  - https://doi.org/10.1016/j.ejcb.2009.10.019
SN  - 0171-9335
ER  - 
TY  - JOUR
A1  - Rawel, Harshadrai Manilal
A1  - Kroll, Jürgen
A1  - Haebel, Sophie
A1  - Peter, Martin G.
T1  - Reactions of a glucosinolate breakdown product (benzyl-isothiocyanate) with myoglobin
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Stöckigt, Detlef
A1  - Haebel, Sophie
T1  - Identification of CID fragments from a protonated glutathione conjugate by isotope-specific MS3 experiments in an ion trap
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Rawel, Harshadrai Manilal
A1  - Kroll, Jürgen
A1  - Riese-Schneider, Brigitte
A1  - Haebel, Sophie
T1  - Physicochemical and enzymatic properties of Benzyl-Isothiocyanate derivatized proteinases
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Haebel, Sophie
A1  - Hejazi, Mahdi
A1  - Frohberg, Claus
A1  - Heydenreich, Matthias
A1  - Ritte, Gerhard
T1  - Mass spectrometric quantification of the relative amounts of C6 and C3 position phosphorylated glucosyl residues in starch
N2  - The quantification of phosphate bound to the C6 and C3 positions of glucose residues in starch has received increasing interest since the importance of starch phosphorylation for plant metabolism was discovered. The method described here is based on the observation that the isobaric compounds glucose-6-phosphate (Glc6P) and glucose-3- phosphate (Glc3P) exhibit significantly different fragmentation patterns in negative ion electrospray tandem mass spectrometry (MS/MS). A simple experiment involving collision-induced dissociation (CID) MS2 spectra of the sample and the two reference substances Glc3P and Glc6P permitted the quantification of the relative amounts of the two compounds in monosaccharide mixtures generated by acid hydrolysis of starch. The method was tested on well-characterized potato tuber starch. The results are consistent with those obtained by NMR analysis. In contrast to NMR, however, the presented method is fast and can be performed on less than 1 mg of starch. Starch samples of other origins exhibiting a variety of phosphorylation degrees were analyzed to assess the sensitivity and robustness of the method.
Y1  - 2008
UR  - http://www.sciencedirect.com/science/journal/00032697
SN  - 0003-2697
ER  - 
TY  - JOUR
A1  - Schweigert, Florian J.
A1  - Raila, Jens
A1  - Haebel, Sophie
T1  - Vitamin A excreted in the urine of canines is associated with a Tamm-Horsfall-like Glycoprotein
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Haebel, Sophie
A1  - Bahrke, Sven
A1  - Peter, Martin G.
T1  - Quantitative sequencing of complex mixtures of heterochitooligosaccharides by vMALDI-linear ion trap mass spectrometry
N2  - Heterochitooligosaccharides possess interesting biol. properties. Isobaric mixts. of such linear heterochitooligosaccharides can be obtained by chem. or enzymic degrdn. of chitosan. However, the sepn. of such mixts. is a challenging anal. problem which is so far unresolved. It is shown that these isobaric mixts. can be sequenced and quantified simultaneously using std. derivatization and multistage tandem mass spectrometric techniques. A linear ion trap mass spectrometer equipped with a vacuum matrix-assisted laser desorption ionization (vMALDI) source is used to perform MS2 as well as MS3 expts. [on SciFinder (R)].
Y1  - 2007
UR  - http://pubs.acs.org/loi/ancham
U6  - https://doi.org/10.1021/Ac062254u
SN  - 0003-2700
ER  - 
TY  - JOUR
A1  - Tsukamoto, Junko
A1  - Haebel, Sophie
A1  - Valenca, Gustavo P.
A1  - Peter, Martin G.
A1  - FRanco, Telma T.
T1  - Enzymatic direct synthesis of acrylic acid esters of mono- and disaccharides
N2  - Background: There is an increased need to replace materials derived from fossil sources by renewables. Sugar- cane derived carbohydrates are very abundant in Brazil and are the cheapest sugars available in the market, with more than 400 million tons of sugarcane processed in the year 2007. The objective of this work was to study the prepn. of sugar acrylates from free sugars and free acrylic acid, thus avoiding the previous prepn. of protected sugar derivs., such as glycosides, or activated acrylates, such as vinyl acrylate. Results: Lipase catalyzed esterification of three mono- and two disaccharides with acrylic acid, in the presence or absence of mol. sieves was investigated. The reactions were monitored by high-performance liq. chromatog. (HPLC) and the products were analyzed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. The main products are mono- and diacrylates, while higher esters are formed as minor products. The highest conversion to sugar acrylates was obsd. for the D-glucose and D- fructose, followed by D-xylose and D-maltose. Mol. sieves had no pronounced effect on the conversion. Conclusions: A feasible method is described to produce and to characterize sugar acrylates, including those contg. more than two acrylate groups. The process for prodn. of these higher esters could potentially be optimized further to produce mols. for crosslinking in acrylate polymn. and other applications. The direct enzymic esterification of free carbohydrates with acrylic acid is unprecedented. [on SciFinder (R)].
Y1  - 2008
UR  - http://www3.interscience.wiley.com/journal/117946200/grouphome/home.html
SN  - 0268-2575
ER  - 
TY  - JOUR
A1  - Bahrke, Sven
A1  - Einarsson, Jon M.
A1  - Gislason, Johannes
A1  - Haebel, Sophie
A1  - Letzel, Matthias C.
A1  - Peter-Katalinic, Jasna
A1  - Peter, Martin G.
T1  - Sequence analysis of chitooligosaccharides by matrix-assisted laser desorption ionization postsource decay mass spectrometry
N2  - Oligosaccharides composed of 2-acetamido-2-deoxy-D-glucopyranose (GlcNAc) and/or 2-amino-2-deoxy-D- glucopyranose (GlcN) were prepd. by chem. degrdn. of chitin or chitosan and sepd. by gel permeation chromatog. Oligosaccharides obtained after enzymic hydrolysis of chitosan [FA 0.19] with a fungal chitinase were derivatized by reductive amination with 2-aminoacridone and sequenced by matrix-assisted laser desorption ionization time-of-flight postsource decay (PSD) mass spectrometry (MS). The sequence of a trimer, D1A2, was established as D-A-A. The compn. of a hexamer D3A3 was .apprx.65% D-A-D-D-A-A and 35% D-D-A-D-A-A. The PSD MS of a nonamer D5A4-amac revealed four isobaric species D-X-Y-D-X-Y-D-A-A, where A is GlcNAc, D is GlcN, and X and Y (X ¹ Y) are mutually either D or A. This structure motif was also obsd. in a dodecamer D7A5 which was composed of eight isobaric sequences of the general formula (D-X-Y)3- D-A-A.
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Grunwaldt, Gisela
A1  - Haebel, Sophie
A1  - Spitz, Christian
A1  - Steup, Martin
A1  - Menzel, Ralf
T1  - Multiple binding sites of fluorescein isothiocyanate moieties on myoglobin : photophysical heterogeneity as revealed by ground- and excited-state spectroscopy
Y1  - 2002
SN  - 1011-1344
ER  - 
TY  - JOUR
A1  - Kehr, Julia
A1  - Haebel, Sophie
A1  - Blechschmidt-Schneider, Sabine
A1  - Willmitzer, Lothar
A1  - Steup, Martin
A1  - Fisahn, Joachim
T1  - Analysis of phloem protein patterns from different organs of Cucurbita maxima Duch. by matrix-assisted laser desorption/ionization time of flight mass spectroscopy combined with sodium dodecyl sufate-polyacryilamide gel electrophoresis
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Haebel, Sophie
A1  - Albrecht, Tanja
A1  - Sparbier, Katrin
A1  - Walden, Peter
A1  - Körner, Roman
A1  - Steup, Martin
T1  - Electrophoresis-related protein modification: alkylation of carboxy residues revealed by mass spectrometry
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Ritte, Gerhard
A1  - Eckermann, Nora
A1  - Haebel, Sophie
A1  - Lorberth, Ruth
A1  - Steup, Martin
T1  - Compartmentation of the starch-related R1 protein in higher plants
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Dauvillee, David
A1  - Chochois, Vincent
A1  - Steup, Martin
A1  - Haebel, Sophie
A1  - Eckermann, Nora
A1  - Ritte, Gerhard
A1  - Ral, Jean-Philippe
A1  - Colleoni, Christophe
A1  - Hicks, Glenn
A1  - Wattebled, Fabrice
A1  - Deschamps, Philippe
A1  - Lienard, Luc
A1  - Cournac, Laurent
A1  - Putaux, Jean-Luc
A1  - Dupeyre, Danielle
A1  - Ball, Steven G.
T1  - Plastidial phosphorylase is required for normal starch synthesis in Chlamydomonas reinhardtii
JF  - The plant journal
N2  - 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.
KW  - Chlamydomonas
KW  - starch
KW  - amylopectin
KW  - (glycogen) starch phosphorylase
Y1  - 2006
U6  - https://doi.org/10.1111/j.1365-313X.2006.02870.x
SN  - 0960-7412
VL  - 48
IS  - 2
SP  - 274
EP  - 285
PB  - Blackwell
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Ritte, Gerhard
A1  - Heydenreich, Matthias
A1  - Mahlow, Sebastian
A1  - Haebel, Sophie
A1  - Koetting, Oliver
A1  - Steup, Martin
T1  - Phosphorylation of C6- and C3-positions of glucosyl residues in starch is catalysed by distinct dikinases
JF  - FEBS letters : the journal for rapid publication of short reports in molecular biosciences
N2  - 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.
KW  - starch phosphorylation
KW  - GWD
KW  - PWD
KW  - P-31 NMR
Y1  - 2006
U6  - https://doi.org/10.1016/j.febslet.2006.07.085
SN  - 0014-5793
VL  - 580
IS  - 20
SP  - 4872
EP  - 4876
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Ritte, Gerhard
A1  - Scharf, Anke
A1  - Eckermann, Nora
A1  - Haebel, Sophie
A1  - Steup, Martin
T1  - Phosphorylation of transitory starch is increased during degradation
N2  - 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
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Albrecht, Tanja
A1  - Haebel, Sophie
A1  - Koch, Anke
A1  - Krause, Ulrike
A1  - Eckermann, Nora
A1  - Steup, Martin
T1  - Yeast glycogenin (Glg2p) produced in Escherichia coli is simultaneously glucosylated at two vicinal tyrosin residues but results in a reduced bacterial glycogen accumulation
N2  - 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
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Deschamps, Philippe
A1  - Haferkamp, Ilka
A1  - Dauvillee, David
A1  - Haebel, Sophie
A1  - Steup, Martin
A1  - Buleon, Alain
A1  - Putaux, Jean-Luc
A1  - Colleoni, Christophe
A1  - d'Hulst, Christophe
A1  - Plancke, Charlotte
A1  - Gould, Sven
A1  - Maier, Uwe
A1  - Neuhaus, Heinz Eckhard
A1  - Ball, Steven G.
T1  - Nature of the periplastidial pathway of starch synthesis in the cryptophyte Guillardia theta
N2  - 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
Y1  - 2006
UR  - http://ec.asm.org/
U6  - https://doi.org/10.1128/Ec.00380-05
SN  - 1535-9778
ER  -