@misc{AntonLaschewsky1994, author = {Anton, Peter and Laschewsky, Andr{\´e}}, title = {Solubilization by polysoaps}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17327}, year = {1994}, abstract = {The aqueous solubilization power of several series of micellar homopolymers and copolymers (polysoaps) is investigated. Using five insoluble or poorly water-soluble dyes, comparisons of the capacities are made with respect ot the influence of structural variables such as the polymer backbone, the polymer geometry, the comonomer content, and the charge of the hydrophilic group. Some guidelines for polysoap structures suited for efficient solubilization are established. Noteworthy is that the solubilization capacities of the polysoaps are neither linked to the ability to reduce the surface tension of water, nor to the polarity of the solubilization sites deduced from spectroscopic probes.}, language = {en} } @misc{AntonLaschewsky1993, author = {Anton, Peter and Laschewsky, Andr{\´e}}, title = {Zwitterionic polysoaps with reduced density of surfactant side groups}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17301}, year = {1993}, abstract = {Several zwitterionic polymers were prepared by radical homopolymerization of surfactant monomers which bear diallyl, diene or vinylcyclopropane moieties. These polymer systems were complemented by alternating copolymers of appropriate zwitterionic vinyl compounds. Thus, polymers with reduced (as compared with simple vinylic homopolymers, or statistical copolymers) and well defined density of surfactant side groups are obtained. The solubilities found for these polymers are dominated by polymer geometry rather than by the balance of hydrophilic and hydrophobic fragments, thus corroborating a main-chain spacer model proposed recently. All water-soluble polymers exhibit characteristic features of classical polysoaps, as shown by surface tension measurements and by solubilization of hydrophobic dyes. In contrast, the water-insoluble copolymers are capable to form stable monolayers at the air-water interface.}, language = {en} } @misc{AntonKoeberleLaschewsky1993, author = {Anton, Peter and K{\"o}berle, Peter and Laschewsky, Andr{\´e}}, title = {Recent developments in the field of micellar polymers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17263}, year = {1993}, abstract = {This article describes recent achievements in the field of micellar polymers, or polysoaps. Taking advantage of zwitterionic model polymers, systematic variations of the molecular architecture have provided an improved understanding of the relationship between the molecular structure of the polymers and their key properties such as surface activity and solubilization capacity. Useful rules are established, which take into account much of the previous data in the literature.}, language = {en} } @misc{LaschewskySchulzHanke1993, author = {Laschewsky, Andr{\´e} and Schulz-Hanke, Wolfgang}, title = {Ring-opening metathesis polymerization of amphiphilic norbornenes functionalized with non-linear optical (NLO) chromophores}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26917}, year = {1993}, abstract = {Contents: Potential of amphiphilic NLO polymers Ring-opening metathesis polymerization (ROMP) Properties of the polymers Monolayer properties Experimental part - Methods - Materials - Analytical data - General polymerization procedure Conclusions}, language = {en} } @misc{KoeberleLaschewskyTsukruk1992, author = {K{\"o}berle, Peter and Laschewsky, Andr{\´e} and Tsukruk, Vladimir}, title = {The structural order of some novel ionic polymers : 1. X-ray scattering studies}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17247}, year = {1992}, abstract = {A set of novel zwitterionic side-chain polyacrylates and polymethacrylates is studied by X-ray scattering. The structural order both in the short-range and long-range scale is investigated. The influence of the polymer backbone, of different locations of the ionic groups in isomeric polymers, of bound water and of added inorganic salts on the bulk structures is studied, and the observed rearrangements are analysed.}, 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{LaschewskyPaulusRingsdorfetal.1992, author = {Laschewsky, Andr{\´e} and Paulus, Wolfgang and Ringsdorf, Helmut and Schuster, A. and Frick, G. and Mathy, A.}, title = {Mixed polymeric monolayers and Langmuir-Blodgett multilayers with functional low molecular weight guest compounds}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17233}, year = {1992}, abstract = {Mixed monolayers and Langmuir-Blodgett multilayers of functional low molecular weight guest compounds, especially nonlinear optical (NLO) dyes, within the matrix of an amphotropic spacer polymer have been prepared. The polymer matrix enabled the transfer of guest compounds not capable of self-organizing at the air-water interface by themselves. The structure of the LB multilayers and the transfer process were studied by small angle X-ray scattering and UV-visible spectroscopy. Good NLO coefficients were found in the mixed films.}, 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{TsukrukMischenkoKoeberleetal.1992, author = {Tsukruk, Vladimir and Mischenko, Nikolay and K{\"o}berle, Peter and Laschewsky, Andr{\´e}}, title = {The structural order of some novel ionic polymers; 2. : Models of molecular packing}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17256}, year = {1992}, abstract = {The molecular packing and spatial correlations of two isomeric zwitterionic polymethacrylates and one polyacrylate analog are studied by means of X-ray analysis and conformational calculations. The analysis of the correlation functions and density distribution profiles suggest a double-layered molecular packing which is discussed for the three polymers investigated, with respect to their different chemical structures. Whereas the zwitterionic polymethacrylates studied exhibit liquid-like short-range order, the polyacrylate analog exhibits an ordered double-layered superstructure.}, language = {en} } @misc{EmbsFunhoffLaschewskyetal.1991, author = {Embs, Frank and Funhoff, Dirk and Laschewsky, Andr{\´e} and Licht, Ulrike and Ohst, Holger and Prass, Werner and Ringsdorf, Helmut and Wegner, Gerhard and Wehrmann, Rolf}, title = {Preformed polymers for Langmuir-Blodgett films- molecular concepts}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17196}, year = {1991}, abstract = {The use of preformed polymers for the preparation of Langmuir-Blodgett (LB) multilayers is reviewed. Principles for polymer self-organization are outlined and the appropriate molecular designs are discussed. Recent developments in the different classes of polymers for LB multilayers are presented, and their outstanding properties highlighted.}, language = {en} } @misc{AntonLaschewsky1991, author = {Anton, Peter and Laschewsky, Andr{\´e}}, title = {Polysoaps via alternating olefin/SO2 copolymers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17216}, year = {1991}, abstract = {Contents: Introduction Results and discussion - Monomers studied - Monomer properties - Polymerization, copolymer composition and general properties - Polymer properties in aqueous solution Conclusion Experimental part - Materials - Copolymerization with S02 (typical procedure) - Methods}, language = {en} } @misc{Laschewsky1991, author = {Laschewsky, Andr{\´e}}, title = {Oligoethyleneoxide spacer groups in polymerizable surfactants}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17221}, year = {1991}, abstract = {Cationic and zwitterionic polymerizable surfactants bearing tri- and tetraethyleneglycol spacer groups between the polymerizable moiety and the surfactant structure were prepared and polymerized. Monomers and polymers were investigated with respect to their aggregation behavior in aqueous systems and compared to analogous monomers and polymers lacking spacer groups. In the case of the monomeric surfactants, the spacer groups depress both the Kraffttemperature and the critical micelle concentration. the area occupied per molecule at the air-water interface is substantially enlarged by the spacers, whereas the depression of surface tension is nearly constant. Although the monomers with and without spacers are true surfactants, all the polymers are water-insoluble, but form monomolecular layers at the air-water interface. In analogy to the monomer behavior, the incorporation of the spacer groups increases the area occupied per repeat unit at the air-water interface substantially, but hardly affects the surface activity.}, language = {en} } @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{PeterFoerster1989, author = {Peter, Martin G. and F{\"o}rster, Hans}, title = {On the structure of Eumelanins : identification of constitutional patterns by solid-state NMR spectroscopy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17027}, year = {1989}, abstract = {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. [...]}, language = {en} } @misc{ErdelenLaschewskyRingsdorfetal.1989, author = {Erdelen, C. and Laschewsky, Andr{\´e} and Ringsdorf, H. and Schneider, J. and Schuster, A.}, title = {Thermal behaviour of polymeric Langmuir-Blodgett multilayers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17378}, year = {1989}, abstract = {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.}, language = {en} } @misc{Laschewsky1989, author = {Laschewsky, Andr{\´e}}, title = {Monolayers and Langmuir-Blodgett multilayers of discotic liquid crystals?}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17396}, year = {1989}, abstract = {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}, language = {en} } @misc{BiddleRickertLandoetal.1989, author = {Biddle, M. B. and Rickert, S. E. and Lando, J. B. and Laschewsky, Andr{\´e}}, title = {The use of the Langmuir-Blodgett technique to obtain ultra-thin polar films}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17185}, year = {1989}, abstract = {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.}, language = {en} } @misc{LaschewskyRingsdorf1988, author = {Laschewsky, Andr{\´e} and Ringsdorf, H.}, title = {Polymerization of amphiphilic dienes in Langmuir-Blodgett multilayers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17176}, year = {1988}, abstract = {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.}, language = {en} } @misc{LupoPrassScheunemannetal.1988, author = {Lupo, Donald and Prass, Werner and Scheunemann, Ude and Laschewsky, Andr{\´e} and Ringsdorf, Helmut and Ledoux, Isabelle}, title = {Second-harmonic generation in Langmuir-Blodgett monolayers of stilbazium salt and phenylhydrazone dyes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17401}, year = {1988}, abstract = {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}, language = {en} } @misc{LaschewskyRingsdorfSchmidtetal.1987, author = {Laschewsky, Andr{\´e} and Ringsdorf, H. and Schmidt, G. and Schneider, J.}, title = {Self-organization of polymeric lipids with hydrophilic spacers in side groups and main chain : investigation in monolayers and multilayers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17147}, year = {1987}, abstract = {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.}, language = {en} } @misc{FerenzPeter1987, author = {Ferenz, Hans-J{\"o}rg and Peter, Martin G.}, title = {The inhibitory effect of sinefungin on juvenile hormone biosynthesis and development in locusts}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16811}, year = {1987}, abstract = {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.}, language = {en} } @misc{KochLaschewskyRingsdorfetal.1986, author = {Koch, Horst and Laschewsky, Andr{\´e} and Ringsdorf, Helmut and Teng, Kang}, title = {Photodimerization and photopolymerization of amphiphilic cinnamic acid derivatives in oriented monolayers, vesicles and solution}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17111}, year = {1986}, abstract = {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.}, language = {en} } @misc{AlbrechtCummingKreuderetal.1986, author = {Albrecht, O. and Cumming, W. and Kreuder, W. and Laschewsky, Andr{\´e} and Ringsdorf, Helmut}, title = {Monolayers of rod-shaped and disc-shaped liquid crystalline compounds at the air-water interface}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17124}, year = {1986}, abstract = {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.}, language = {en} } @misc{LaschewskyRingsdorfSchneider1986, author = {Laschewsky, Andr{\´e} and Ringsdorf, H. and Schneider, J.}, title = {Oriented supramolecular systems-polymeric monolayers and multilayers from prepolymerized amphiphiles}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17131}, year = {1986}, abstract = {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.}, language = {en} } @misc{LaschewskyRingsdorfSchmidt1985, author = {Laschewsky, Andr{\´e} and Ringsdorf, H. and Schmidt, G.}, title = {Polymerization of hydrocarbon and fluorocarbon amphiphiles in Langmuir-Blodgett multilayers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17096}, year = {1985}, abstract = {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.}, language = {en} } @misc{ElbertLaschewskyRingsdorf1985, author = {Elbert, R. and Laschewsky, Andr{\´e} and Ringsdorf, H.}, title = {Hydrophilic spacer groups in polymerizable lipids: formation of biomembrane models from bulk polymerized lipids}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17361}, year = {1985}, abstract = {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.}, language = {en} } @misc{FerenzPeterBerg1983, author = {Ferenz, Hans-J{\"u}rgen and Peter, Martin G. and Berg, Dieter}, title = {Inhibition of farnesoic acid methyltransferase by sinefungin}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17016}, year = {1983}, abstract = {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.}, 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{Peter1980, author = {Peter, Martin G.}, title = {Products of in vitro oxidation of N-acetyldopamine as possible components in the sclerotization of insect cuticle}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16759}, year = {1980}, abstract = {[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.}, language = {en} }