@misc{BubeckLaschewskyLupoetal.1991, author = {Bubeck, Christoph and Laschewsky, Andr{\´e} and Lupo, Donald and Neher, Dieter and Ottenbreit, Petra and Paulus, Wolfgang and Prass, Werner and Ringsdorf, Helmut and Wegner, Gerhard}, title = {Amphiphilic dyes for nonlinear optics: Dependence of second harmonic generation on functional group substitution}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17201}, year = {1991}, language = {en} } @misc{SchmaelzlinDongenKlimantetal.2005, author = {Schm{\"a}lzlin, Elmar and Dongen, Joost T. van and Klimant, Ingo and Marmod{\´e}e, Bettina and Steup, Martin and Fishahn, Joachim and Geigenberger, Peter and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {An optical multifrequency phase-modulation method using microbeads for measuring intracellular oxygen concentrations in plants}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12232}, year = {2005}, abstract = {A technique has been developed to measure absolute intracellular oxygen concentrations in green plants. Oxygen-sensitive phosphorescent microbeads were injected into the cells and an optical multifrequency phase-modulation technique was used to discriminate the sensor signal from the strong autofluorescence of the plant tissue. The method was established using photosynthesis-competent cells of the giant algae Chara corallina L., and was validated by application to various cell types of other plant species.}, language = {en} } @misc{BillardAnsoborloAppersonetal.2003, author = {Billard, Isabelle and Ansoborlo, Eric and Apperson, Kathleen and Arpigny, Sylvie and Azenha, M. Emilia and Birch, David and Bros, Pascal and Burrows, Hugh D. and Choppin, Gregory and Kumke, Michael Uwe}, title = {Aqueous solutions of Uranium(VI) as studied by time-resolved emission spectroscopy : a Round-Robin Test}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12318}, year = {2003}, abstract = {Results of an inter-laboratory round-robin study of the application of time-resolved emission spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media are presented. The round-robin study involved 13 independent laboratories, using various instrumentation and data analysis methods. Samples were prepared based on appropriate speciation diagrams and, in general, were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (1) acidic medium where UO22+aq is the single emitting species, (2) uranyl in the presence of fluoride ions, (3) uranyl in the presence of sulfate ions, and (4) uranyl in aqueous solutions at different pH, promoting the formation of hydrolyzed species. Results between the laboratories are compared in terms of the number of decay components, luminescence lifetimes, and spectral band positions. The successes and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.}, language = {en} } @misc{KortPeterKoopmanschap1983, author = {Kort, C. A. D. de and Peter, Martin G. and Koopmanschap, A. B.}, title = {Binding and degradation of juvenile hormone III by haemolymph proteins of the Colorado potato beetle: a re-examination}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16777}, year = {1983}, abstract = {The haemolymph of the adult Colorado potato beetle, Lepinotarsa decemlineata Say, contains a high molecular weight (MW > 200,000) JH-III specific binding protein. The Kd value of the protein for racemic JH-III is 1.3 ± 0.2 × 10-7 M. It has a lower affinity for racemic JH-I and it does not bind JH-III-diol or JH-III-acid. The binding protein does discriminate between the enantiomers of synthetic, racemic JH-III as was determined by stereochemical anaysis of the bound and the free JH-III. Incubation of racemic JH-III with crude haemolymph results in preferential formation of (10S)-JH-III-acid, the unnatural configuration. The JH-esterase present in L. decemlineata haemolymph is not enantioselective. It is concluded that the most important function of the binding protein is that of a specific carrier, protecting the natural hormone against degradation by esterases. The carrier does not protect JH-I as efficiently as the lower homologue.}, language = {en} } @misc{PeterAndersenHartmannetal.1992, author = {Peter, Martin G. and Andersen, Svend Olav and Hartmann, Rudolf and Miessner, Merle and Roepstorff, Peter}, title = {Catecholamine-protein conjugates : isolation of 4-phenylphenoxazin-2-ones from oxidative coupling of N-acetyldopamine with alipathic amino acids}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17571}, year = {1992}, abstract = {4-Phenylphenoxazinones were isolated after biomimetic oxidation, using diphenoloxidases of insect cuticle, mushroom tyrosinase, or after autoxidation of N-acetyldopamine (Image ) in the presence of β-alanine, β-alanine methyl ester or N-acetyl-L-lysine. They are formed presumably by addition of 2-aminoalkyl-5-alkylphenols to the o-quinone of biphenyltetrol which, in turn, arises from oxidative coupling of. The structures of present the first examples for the assembly of reasonably stable intermediates in the rather complex process of chemical modifications of aliphatic amino acid residues by o-quinones.}, language = {en} } @misc{Peter1989, author = {Peter, Martin G.}, title = {Chemische Modifikation von Biopolymeren durch Chinone und Chinonmethide}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16802}, year = {1989}, abstract = {Chinone und Vorstufen, die oxidativ in Chinone und/oder Chinonmethide umgewandelt werden k{\"o}nnen, sind in der Natur weit verbreitet. Als sekund{\"a}re Naturstoffe wirken sie h{\"a}ufig antibiotisch, cytotoxisch, aber auch pathogen, und eine Reihe von Pflanzen und Tieren benutzt chinoide Substanzen als Abwehrstoffe, oft mit spektakul{\"a}rem Erfolg. Auf makromolekularer Ebene spielen Chinonmethide im Pflanzenreich eine Schl{\"u}sselrolle bei der Biosynthese von Lignin, w{\"a}hrend die Bildung von Melanoproteinen ein Beispiel f{\"u}r Reaktionen von o-Chinonen im Tierreich ist. Bei den Insekten dienen Chinone und Chinonmethide zur Bildung des lebensnotwendigen Exoskeletts. Die Reaktivit{\"a}t von Chinonen in biologischen Systemen hat auch f{\"u}r den Menschen unmittelbare Bedeutung in pharmazeutischer, toxikologischer und technologischer Hinsicht. Den Beispielen in diesem Aufsatz liegt ein gemeinsames Prinzip zugrunde, n{\"a}mlich die chemische Modifikation von Biopolymeren durch Chinone und Chinonmethide. Wie sich besonders bei einer detaillierteren Betrachtung der Reaktionen zeigt, die zur Sklerotisierung der Insektencuticula f{\"u}hren, sind in den letzten Jahren wichtige neue Erkenntnisse hinzugekommen, die vor allem durch die modernen Methoden der Stofftrennung und der Festk{\"o}rper-NMR-Spektroskopie erm{\"o}glicht worden sind.}, language = {de} } @misc{SchaeferBungNest2008, author = {Sch{\"a}fer-Bung, Boris and Nest, Mathias}, title = {Correlated dynamics of electrons with reduced two-electron density matrices}, issn = {1866-8372}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-41774}, year = {2008}, abstract = {We present an approach to the correlated dynamics of many-electron systems. We show, that the twoelectron reduced density matrix (2RDM) can provide a suitable description of the real time evolution of a system. To achieve this, the hierarchy of equations of motion must be truncated in a practical way. Also, the computational effort, given that the 2RDM is represented by products of two-electron determinants, is discussed, and numerical model calculations are presented.}, language = {en} } @misc{AndersenPerterRoepstorff1992, author = {Andersen, Svend Olav and Perter, Martin G. and Roepstorff, Peter}, title = {Cuticle-catalyzed coupling between N-acetylhistidine and N-acetyldopamine}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16762}, year = {1992}, abstract = {Several types of insect cuticle contain enzymes catalyzing the formation ofof adducts between N-acetyldopamine (NADA) and N-acetylhistidine (NAH). Two such adducts, NAH-NADA-I and NAH NADA-II, have been isolated and their structures determined. In one of the adducts the link connecting the two residues occurs between the I-position (ß-position) in the NADA side chain and the 1-N atom (τ-N) in the imidazole ring of histidine. Diphenoloxidase activity alone is not sufficient for formation of this adduct, whereas extracts containing both diphenoloxidase and o-quinone-p-quinone methide isomerase activities catalyze the coupling reaction. The adduct consists of a mixture of two diastereomers and they are presumably formed by spontaneous reaction between enzymatically produced NADA-p-quinone methide and N-acetylhistidine. The other adduct has been identified as a ring addition product of N-acetylhistidine and NADA. In contrast to the former adduct it can be formed by incubation of the two substrates with mushroom tyrosinase alone. An adduct between N-acetylhistidine and the benzodioxan-type NADA-dimer is produced in vitro, when the N-acetylhistidine-NADA adduct is incubated with NADA and locust cuticle containing a 1,2-dehydro-NADA generating enzyme system. Trimeric NADA-polymerization products of the substituted benzodioxan-type have been obtained from in vivo sclerotized locust cuticle, confirming the ability of cuticle to produce NADA-oligomers. The results indicate that some insect cuticles contain enzymes promoting linkage of oxidized NADA to histidine residues. It is suggested that histidine residues in the cuticular proteins can serve as acceptors for oxidized NADA and that further addition of NADA-residues to the phenolic groups of bound NADA can occur, resulting in formation of protein-linked NADA-oligomers. The coupling reactions identified may be an important step in natural cuticular sclerotization.}, language = {en} } @misc{DoscheKumkeLoehmannsroebenetal.2004, author = {Dosche, Carsten and Kumke, Michael Uwe and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Ariese, F. and Bader, Arjen N. and Gooijer, C. and Miljanic, O. S. and Iwamoto, M. and Vollhardt, K. Peter C. and Puchta, R. ; van Eikema Hommes, N. J. R.}, title = {Deuteration effects on the vibronic structure of the fluorescence spectra and the internal conversion rates of triangular [4]Phenylene}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-11881}, year = {2004}, abstract = {Deuteration effects on the vibronic structure of the emission and excitation spectra of triangular [4]phenylene (D3h[4]phenylene) were studied using laser-excited Shpolskii spectroscopy (LESS) in an octane matrix at 4.2 K. For correct assignment of the vibrational modes, the experimental results were compared with calculated frequencies (B3LYP/6-31G*). CH vibrations were identified by their characteristic isotopic shifts in the spectra of deuterated triangular [4]phenylenes. Two CC stretching modes, at 100 cm-1 and 1176 cm-1, suitable as probes for bond strength changes in the excited state, were identified. The isotope effect on the internal conversion rates of triangular [4]phenylene was evaluated from measurements of temperature dependent lifetime. Isotope dependency and the magnitude of the internal conversion rates indicate that internal conversion in triangular [4]phenylene is most likely induced by CH vibrations. The results obtained by LESS and lifetime measurements were compared with PM3 PECI calculations of the excited state structure. The theoretical results and the relation between ground and excited state vibration energies of the 1176 cm-1 probe vibration indicate a reduction of bond alternation of the central cyclohexatriene ring in the excited state.}, language = {de} } @misc{TsukamotoHeabelValencaetal.2008, author = {Tsukamoto, Junko and Heabel, Sophie and Valenca, Gustavo P. and Peter, Martin and Franco, Telma}, title = {Enzymatic direct synthesis of acrylic acid esters of mono- and disaccharides}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-42652}, year = {2008}, abstract = {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 preparation of sugar acrylates from free sugars and free acrylic acid, thus avoiding the previous preparation of protected sugar derivatives, 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 molecular sieves was investigated. The reactions were monitored by high-performance liquid chromatography (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 observed for the D-glucose and D-fructose, followed by D-xylose and D-maltose. Molecular sieves had no pronounced effect on the conversion CONCLUSIONS: A feasible method is described to produce and to characterize sugar acrylates, including those containing more than two acrylate groups. The process for production of these higher esters could potentially be optimized further to produce molecules for cross-linking in acrylate polymerization and other applications. The direct enzymatic esterification of free carbohydrates with acrylic acid is unprecedented.}, language = {en} }