TY - GEN A1 - Peter, Martin G. T1 - Products of in vitro oxidation of N-acetyldopamine as possible components in the sclerotization of insect cuticle N2 - [1-14C]-N-Acetyldopamine (NADA) was oxidized in the presence of methyl [3-3H]-β-alanate with mushroom tyrosinase. The complex mixture of reaction products was partly resolved by chromatographic procedures and analyzed by spectroscopic methods. Methyl-β-alanate is incorporated to only a small extent into oxidation products of NADA which inter alia are presumed to be oligomeric hydroxyquinones. After oxidation of [1-14C, 2-3H]-NADA with preparations from tanning Manduca sexta pupal cuticle, N-acetylnoradrenalin was identified as one of the products. Binding of radioactivity to melanin-like material was also observed. These results suggest that oxidation products different from those formulated usually for the crosslinkages between protein amino groups and N-acetyldopaquinone are deposited in darkly brown coloured insect cuticles during sclerotization. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 041 KW - N-acetyldopamine KW - sclerotization KW - tyrosinase; o-quinones KW - tanning agents Y1 - 1980 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16759 ER - TY - GEN A1 - Ferenz, Hans-Jürgen A1 - Peter, Martin G. A1 - Berg, Dieter T1 - Inhibition of farnesoic acid methyltransferase by sinefungin N2 - Sinefungin inhibited the S-adenosylmethionine-dependent farnesoic acid methyltransferase in a cell-free system containing a homogenate of corpora allata from female locusts, Locusta migratoria. The enzyme catalyzed the penultimate step of juvenile hormone biosynthesis in the insects. Culturing corpora allata in the presence of sinefungin greatly suppressed juvenile hormone production. The following in vivo effects were visible after injection of the inhibitor: increase in mortality and reduction of total haemolymph protein liter and ovary fresh weight, as well as length of terminal oocytes. Attempts to reverse these effects by topical application of the juvenile hormone analog ZR-515 (methoprene) were only partly successful. Therefore, the in vivo effects may be due to a general inhibition of methyltransferase enzymes in the insect. Sinefungin appeared to be of potential interest as the first representative of a new class of insect growth regulators. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 077 KW - Juvenile hormone analogue KW - Orthoptera KW - Juvenile hormone KW - Biosynthesis KW - Enzyme KW - Corpora allata KW - In vitro KW - Biological activity KW - Enzyme inhibitor Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17016 ER - TY - GEN A1 - Kort, C. A. D. de A1 - Peter, Martin G. A1 - Koopmanschap, A. B. T1 - Binding and degradation of juvenile hormone III by haemolymph proteins of the Colorado potato beetle: a re-examination N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 068 KW - Juvenile hormone KW - Leptinotarsa decemlineata KW - JH-III-specific carrier protein KW - enantioselectivity Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16777 ER - TY - GEN A1 - Peter, Martin G. A1 - Stupp, Hans-Peter A1 - Lentes, Klaus-Ulrich T1 - Umkehr der Enantioselektivität bei der enzymatischen Hydrolyse von Juvenilhormon als Ergebnis einer Proteinfraktionierung N2 - Aus dem Inhalt: Die Juvenilhormone 1a-c werden im Blut von Insekten enzymatisch zu den biologisch inaktiven Sluren hydrolysiert. Bei der Hydrolyse von racemischem 1c im Blut der Wanderheuschrecke Locusta migratoria wird ein Umsatz von 40-60% erreicht. Das unumgesetzte Edukt enthällt einen Überschuß an natürlich konfiguriertem (10R)-1c (e.e. 47.2%). Wir konnten zeigen, daß das in der Hämolymphe vorhandene Hormon-Bindungsprotein bevorzugt mit (10R)- 1c assoziiert. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 052 Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17001 ER - TY - GEN A1 - Laschewsky, André A1 - Ringsdorf, H. A1 - Schmidt, G. T1 - Polymerization of hydrocarbon and fluorocarbon amphiphiles in Langmuir-Blodgett multilayers N2 - Langmuir-Blodgett multilayers of polymerizable carboxylic acids with hydrocarbon or fluorocarbon chains were prepared. The multilayers were polymerized by UV light and the reactions were studied by UV/visible spectroscopy. The polyreactions strongly influence the multilayer structures which were investigated by X-ray small-angle scattering and scanning electron microscopy. The spreading behaviour of the monomers, the preparation of multilayers, their reactivities in multilayers and structural effects caused by the polyreactions are discussed with regard to the hydrophilic head groups, the polymerizable groups and the hydrophobic chains. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 055 Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17096 ER - TY - GEN A1 - Elbert, R. A1 - Laschewsky, André A1 - Ringsdorf, H. T1 - Hydrophilic spacer groups in polymerizable lipids: formation of biomembrane models from bulk polymerized lipids N2 - A variety of polymerizable lipids containing a hydrophilic spacer group between the reactive group and the main amphiphilic structure have been synthesized. They were investigated in monolayers, liposomes, and multilayers. When the spacer concept was used, efficient decoupling of the motions of the polymeric chain and the amphiphilic side groups is achieved. Thus, the often found loss of the important fluid phases by polymerization is avoided. Polymeric monolayers of the spacer lipid, prepared either by polymerization in the monolayer or by spreading of prepolymerized lipid, exhibit nearly identical surface pressure-area diagrams. Most distinctly, the successful decoupling of the motions of the polymer main chain and the membrane forming amphiphilic side groups is demonstrated by the self-organization of bulk polymerized spacer lipids to polymeric liposomes. In addition, spacer lipids are able to build polymeric Langmuir-Blodgett multilayers. The decoupling of the polymer main chain and the membrane-forming amphiphilic side groups enables the deposition of already polymeric monolayers onto supports to form defined multilayers. If, alternatively, monomeric monolayers are deposited and polymerized on the support, defects in the layers due to structural changes during the polymerization are avoided by the flexible spacer group. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 095 Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17361 ER - TY - GEN A1 - Koch, Horst A1 - Laschewsky, André A1 - Ringsdorf, Helmut A1 - Teng, Kang T1 - Photodimerization and photopolymerization of amphiphilic cinnamic acid derivatives in oriented monolayers, vesicles and solution N2 - Cinnamic acid moieties were incorporated into amphiphilic compounds containing one and two alkyl chains. These lipid-like compounds with photoreactive units undergo self-organization to form monolayers at the gas-water interface and bilayer structures (vesicles) in aqueous solutions. The photoreaction of the cinnamic acid moiety induced by 254 nm UV light was investigated in the crystalline state, in monolayers, in vesicles and in solution in organic solvents. The single-chain amphiphiles undergo dimerization to yield photoproducts with twice the molecular weight of the corresponding monomers in organized systems. The photoreaction of amphiphiles containing two cinnamic acid groups occurs via two mechanisms: The intramolecular dimerization produces bicycles, with retention of the molecular weight of the corresponding monomer. The intermolecular reaction leads to oligomeric and polymeric photoproducts. In contrast to the single-chain amphiphiles, photodimerization processes of lipoids containing two cinnamic acid moieties also occur in solution in organic solvents. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 078 Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17111 ER - TY - GEN A1 - Albrecht, O. A1 - Cumming, W. A1 - Kreuder, W. A1 - Laschewsky, André A1 - Ringsdorf, Helmut T1 - Monolayers of rod-shaped and disc-shaped liquid crystalline compounds at the air-water interface N2 - Calamitic (rod-shaped) and discotic (disc-shaped) thermotropic liquid crystalline (LC) compounds were spread at the air-water interface, and their ability to form monolayers was studied. The calamitic LCs investigated were found to form monolayers which behave analogously to conventional amphiphiles such as fatty acids. The spreading of the discotic LCs produced monolayers as well, but with a behaviour different from classical amphiphiles. The areas occupied per molecule are too small to allow the contact of all hydrophilic groups with the water surface and the packing of all hydrophobic chains. Various molecular arrangements of the discotics at the water surface to fit the spreading data are discussed. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 079 KW - Monolayers KW - liquid crystals KW - discotics Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17124 ER - TY - GEN A1 - Laschewsky, André A1 - Ringsdorf, H. A1 - Schneider, J. T1 - Oriented supramolecular systems-polymeric monolayers and multilayers from prepolymerized amphiphiles N2 - Oriented polymeric membranes were originally prepared by polymerization or polycondensation of preoriented monomers. The introduction of hydrophilic spacer groups into the polymeric amphiphiles allowed the formation of highly ordered systems (monolayers, liposomes, multilayers) from prepolymerized amphiphiles: due to the partial decoupling of the different mobilities and orientation tendencies of the polymer chain and the amphiphilic side groups, these polymers are able to self-organize. In monolayer experiments the high order of these membranes could be demonstrated by their surface pressure area-diagrams. In addition the combination of order and mobility of these spacer groups containing polymeric amphiphiles allowed the formation of Langmuir-Blodgett-multilyers with a high layer correlation. Thus, disturbancies in highly oriented layers can be avoided normally taking place during the polymerization reaction (e.g. contractions) or oriented monomeric layers. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 056 Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17131 ER - TY - GEN A1 - Laschewsky, André A1 - Ringsdorf, H. A1 - Schmidt, G. A1 - Schneider, J. T1 - Self-organization of polymeric lipids with hydrophilic spacers in side groups and main chain : investigation in monolayers and multilayers N2 - Several polymerizable lipids were synthesized and polymerized to amphiphilic homopolymers and to copolymers with the help of hydrophilic comonomers. The self-organization of these polymeric lipids was investigated in monolayers and Langmuir-Blodgett multilayers. The self-organization of these polymers in model membranes is due to hydrophilic spacer groups in the amphiphilic side groups as well as to hydrophilic spacer groups in the polymer backbone. Thus, highly ordered monolayers and LB-multilayers are easily obtained. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 057 Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17147 ER - TY - GEN A1 - Ferenz, Hans-Jörg A1 - Peter, Martin G. T1 - The inhibitory effect of sinefungin on juvenile hormone biosynthesis and development in locusts N2 - The antibiotic fungal metabolite sinefungin is a potent inhibitor of S-adenosylmethionine-acceptor methyltransferases. Its effect on insect metabolism and especially on corpora allata farnesoic acid methyltransferase, which catalyzes the penultimate step of juvenile hormone biosynthesis, was investigated in Locusta migratoria. Injection of sinefungin results in a delay of imaginal molt and in suppression of ovary development. Isolated corpora allata are unable to synthesize juvenile hormone III in the presence of more than 1.0 mM sinefungin. In a cell-free system containing the S-adenosylmethionine-dependent farnesoic acid methyltransferase from corpora allata sinefungin is a competitive inhibitor of the synthesis of methylfarnesoate with Ki of 1 μM. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 076 KW - Locust KW - sinefungin KW - O-methyltransferase KW - juvenile hormone biosynthesis Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16811 ER - TY - GEN A1 - Laschewsky, André A1 - Ringsdorf, H. T1 - Polymerization of amphiphilic dienes in Langmuir-Blodgett multilayers N2 - Amphiphilic derivatives of octadiene and docosadiene were investigated in monolayers and Langmuir-Blodgett multilayers, with respect to their self-organization and their polymerization behavior. All amphiphiles investigated form monolayers. However, only acid and alcohol derivatives were able to build up multilayers. Those multilayers are rapidly photopolymerized in the layers via a two-step process: Irradiation with long-wavelength UV light yields soluble polymers, whereas additional irradiation with sfiort-wavelength UV light produces insoluble and presumably cross-linked polymers. The reaction meclianism is discussed according to the polymer characterization by UV spectroscopy, small-angle X-ray scattering, NMR spectroscopy, and gel permeation chromatography. All multilayers undergo structural changes during the polymerization; substantial changes result in defects in the polymerized layers as observed by scanning electron microscopy. In contrast to the acids and alcohols, the deposition of monolayers of the aldehyde derivatives did not yield well-ordered multilayers, but rather amorphous films. In this different film structure, the photopolymerization process differs from the one observed in multilayers. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 058 Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17176 ER - TY - GEN A1 - Lupo, Donald A1 - Prass, Werner A1 - Scheunemann, Ude A1 - Laschewsky, André A1 - Ringsdorf, Helmut A1 - Ledoux, Isabelle T1 - Second-harmonic generation in Langmuir-Blodgett monolayers of stilbazium salt and phenylhydrazone dyes N2 - Contents: 1. INTRODUCTION 2. SYNTHESIS OF THE COMPOUNDS 3. PREPARATION AND CHARACTERIZATION OF MONOLAYERS A. Monolayer Isotherms B. Langmuir-Blodgett Monolayer Films 4. EXPERIMENTAL SETUP FOR NONLINEAR MEASUREMENTS 5. NONLINEAR OPTICAL PROPERTIES 6. DISCUSSION 7. CONCLUSION T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 094 Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17401 ER - TY - GEN A1 - Peter, Martin G. A1 - Förster, Hans T1 - On the structure of Eumelanins : identification of constitutional patterns by solid-state NMR spectroscopy N2 - Aus dem Inhalt: Melanins are complex polyphenolic polymers. They are usually formed in nature by enzyme-catalyzed oxidative polymerization of o-diphenols. The deep black eumelanins, derived from Dopa 1 or dopamine 3, are distinguished from the yellow to brown phaeomelanins obtained from Dopa in the presence of cysteine. Characteristic of eumelanins are the indole units, which are formed from catecholamines by intramolecular addition of the amino groups to the oxidatively generated o-quinones. [...] T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 053 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17027 ER - TY - GEN A1 - Erdelen, C. A1 - Laschewsky, André A1 - Ringsdorf, H. A1 - Schneider, J. A1 - Schuster, A. T1 - Thermal behaviour of polymeric Langmuir-Blodgett multilayers N2 - Langmuir-Blodgett multilayers of hydrocarbon and fluorocarbon polymers with hydrophilic spacer, lipid-polyelectrolyte complexes and mesogenic polymers have been prepared. The thermal behaviour of the multilayers was studied by small angle X-ray scattering, IR and UV—visible spectroscopy. Good thermal stabilities were found for the various classes of polymers. In addition, for both complexed multilayers and mesogenic polymer films, reorientation processes were observed. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 080 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17378 ER - TY - GEN A1 - Peter, Martin G. T1 - Chemische Modifikation von Biopolymeren durch Chinone und Chinonmethide N2 - Chinone und Vorstufen, die oxidativ in Chinone und/oder Chinonmethide umgewandelt werden können, sind in der Natur weit verbreitet. Als sekundäre Naturstoffe wirken sie häufig antibiotisch, cytotoxisch, aber auch pathogen, und eine Reihe von Pflanzen und Tieren benutzt chinoide Substanzen als Abwehrstoffe, oft mit spektakulärem Erfolg. Auf makromolekularer Ebene spielen Chinonmethide im Pflanzenreich eine Schlüsselrolle bei der Biosynthese von Lignin, während die Bildung von Melanoproteinen ein Beispiel für Reaktionen von o-Chinonen im Tierreich ist. Bei den Insekten dienen Chinone und Chinonmethide zur Bildung des lebensnotwendigen Exoskeletts. Die Reaktivität von Chinonen in biologischen Systemen hat auch für den Menschen unmittelbare Bedeutung in pharmazeutischer, toxikologischer und technologischer Hinsicht. Den Beispielen in diesem Aufsatz liegt ein gemeinsames Prinzip zugrunde, nämlich die chemische Modifikation von Biopolymeren durch Chinone und Chinonmethide. Wie sich besonders bei einer detaillierteren Betrachtung der Reaktionen zeigt, die zur Sklerotisierung der Insektencuticula führen, sind in den letzten Jahren wichtige neue Erkenntnisse hinzugekommen, die vor allem durch die modernen Methoden der Stofftrennung und der Festkörper-NMR-Spektroskopie ermöglicht worden sind. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 043 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16802 ER - TY - GEN A1 - Laschewsky, André T1 - Monolayers and Langmuir-Blodgett multilayers of discotic liquid crystals? N2 - Contents: 1. Discotic Liquid Crystals 2. Monolayers and Langmuir-Blodgett Multilayers 3. Theoretical Considerations on the Molecular Packing of Discotic LCs in Monolayers and Multilayers 4. Spreading Experiments with Discotic LCs 5. LB-Multilayers of Discotic LCs 6. Polymeric Discotic LCs 7. Summary T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 061 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17396 ER - TY - GEN A1 - Biddle, M. B. A1 - Rickert, S. E. A1 - Lando, J. B. A1 - Laschewsky, André T1 - The use of the Langmuir-Blodgett technique to obtain ultra-thin polar films N2 - The piezoelectric and pyroelectric properties of oriented films possessing dipole moments are increasingly being used in pressure, acoustic, thermal and optical devices. The performance of these devices in many applications may be enhanced by thin-film technology.The developing Langmuir-Blodgett thin-film deposition technique offers the opportunity to obtain highly oriented and uniform organic-based films in the 10–5000 nm thickness range. Special techniques must be used, however, to assemble these molecules in such a way as to result in polar multilayer films. Several possible deposition techniques are investigated, with one resulting in a polar and pyroelectric film about 50 nm thick. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 098 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17185 ER - TY - GEN A1 - Peter, Martin G. A1 - Förster, Hans T1 - Zur Struktur von Eumelaninen : Identifizierung von Konstitutionsmustern durch Festkörper-NMR-Spektroskopie T1 - On the Structure of Eumelanins : Identification of Constitutional Patterns by Solid-state NMR Spectroscopy N2 - Aus dem Inhalt: Melanine sind komplexe polyphenolische Polymere. In der Natur entstehen sie durch meist enzymkatalysierte oxidative Polymerisation von o-Diphenolen. Man unterscheidet die aus Dopa 1 oder Dopamin 3 hervorgehenden, tiefschwarzen Eumelanine von den aus Dopa in Gegenwart von Cystein entstehenden, gelben bis braunen Phaomelaninen. [...] T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 054 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17038 ER - TY - GEN A1 - Peter, Martin G. A1 - Boldt, Peter C. A1 - Niederstein, Yvonne A1 - Peter-Katalinić, Jasna T1 - Synthesen von Galactose-Cluster-haltigen Steroid-Derivaten N2 - The synthesis of galactose clusters that are linked to a steroid moiety by a peptide-like spacer unit is described. The galactose cluster is obtained by Koenigs-Knorr glycosylation of TRIS-Gly-Fmoc (2b) under Helferich conditions. Peptide and ester bonds are formed after activation of carboxylic acids as diphenylthiophene dioxide (TDO) esters. 6a is synthesized in a convergent way by coupling of (Ac4Gal)3-TRIS-Gly (3e) with cholesteryl TDO succinate (5b). Coupling of (Ac4Gal)3-TRIS-Gly hydrogen succinate (3f) with Gly-O-Chol (5d) by means of EEDQ yields 6d. Reaction of (Ac4Gal)3-TRIS-Gly-SUCC-O-TDO (3g) with 25-hydroxycholesterol leads in a linear sequence to the oxysterol derivative 6f. Selective cleavage of the acetyl groups from galactose units yields the known compound 6b and the new derivatives 6e and 6g. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 042 KW - Glycoconjugates KW - Galactosides KW - Steroid esters KW - Amphiphiles KW - Glycopeptides Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16783 ER -