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  • 1
    Electronic Resource
    Electronic Resource
    Multiconformational synthetic polypeptides (1981)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 103 (1981), S. 6319-6323 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00411a009
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  • 2
    Electronic Resource
    Electronic Resource
    β-structures of polypeptides with L- and D-residues (1980)
    Springer
    Journal of molecular evolution 15 (1980), S. 231-238 
    Details
    ISSN: 1432-1432
    Keywords: β-structure ; Poly-DL-peptides ; Kinetics of hydrolysis ; Enantiomer enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary It was previously shown that nuclei ofβ-sheets surrounded by unordered segments are formed in polypeptide chains built up with alternating hydrophobic and hydrophilic residues and containing both L- and D-enantiomers. It was also established that segments of residues having the same configuration tend to segregate in these nuclei when the starting composition of stereomonomers departs from the racemic mixture. Soft acidic hydrolysis of these polymers has been studied. Kinetic measurements show two pseudo first order rate constants, in agreement with the existence of two conformational species. The unordered part of the chains is hydrolyzed more rapidly, allowing the isolation of aβ-fraction enriched in one enantiomer. Thus, a plausible process of enrichment in enantiomer during prebiotic evolution has been described, which however does not explain the preference of one enantiomer over the other one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732950
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  • 3
    Electronic Resource
    Electronic Resource
    β-structures of polypeptides with L- and D-residues (1979)
    Springer
    Journal of molecular evolution 13 (1979), S. 35-46 
    Details
    ISSN: 1432-1432
    Keywords: β-structure ; Poly DL-peptides ; Enantiomer enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A series of five alternating poly(leucyl-lysyl) samples with varying amounts of L- and D-residues randomly distributed along the chain, but evenly shared out amongst leucyl and lysyl residues were synthesized by condensation of a mixture of the four diastereoisomeric dipeptidep-nitro-phenylesters. Their behavior in aqueous solution at various ionic strengths was studied by infrared spectroscopy which allowed measurement of the total amount ofβ-structures, and by circular dichroism which gives the excess of L-residues over D-residues in the same structures. Comparison with the properties of the all L-poly(Lys-Leu-Lys-Leu) shows that incorporation of a few D-residues in a L-chain seems to reduce the width of theβ-sheets obtained in presence of salt. Higher proportions of D-isomers prevent the coil →β transition from occurring when the ionic strength is increased except for segments containing at least 6 to 7 adjacent residues of the same configuration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732752
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  • 4
    Electronic Resource
    Electronic Resource
    β-structures of polypeptides with L- and D-residues (1979)
    Springer
    Journal of molecular evolution 13 (1979), S. 47-56 
    Details
    ISSN: 1432-1432
    Keywords: β-structure ; Poly DL-peptides ; Statistical analysis ; Enantiomer enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The possible formation ofβ-structures from polypeptide chains with L-and D-residues randomly distributed was statistically analyzed within the frame of two hypotheses. Firstly, only those segments containing residues of identical chirality can associate to form antiparallelβ-structures, and secondly these segments must have a minimum length. The influence of different factors was examined: initial ratio of the L-and D-monomer, minimum length required for the segments to be incorporated intoβ-sheets, average length of the peptide molecules, and stereoselectivity in the course of the polymerization process. The results show that in all cases nuclei ofβ-sheets surrounded by random coil segments are formed, the optical activity of which very rapidly increases to purity when the initial ratio of monomers deviates from the racemic mixture. This suggests experiments to enrich the system in one enantiomer. Comparison is made with the corresponding behavior and properties of the a-helical structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732753
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  • 5
    Electronic Resource
    Electronic Resource
    Membrane-modifying properties of the pore-forming peptaibols saturnisporin SA IV and harzianin HA V (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 105 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Harzianin HA V and saturnisporin SA IV are α-amino isobutyric-containing peptides with 18- and 20-residue chain length, respectively. They were isolated from in vitro cultures of Trichoderma species and their sequences were determined by the combined use of positive ion FAB mass spectrometry and NMR. In organic solvent solution, both peptides exhibited the same predominant α-helical secondary structure including a hinge at the level of the central Pro residue, as deduced from NMR data. Their interaction with neutral phospholipid bilayers was shown to induce leakage of the material entrapped in small unilamellar vesicles composed of egg phosphatidylcholine/cholesterol (7/3). When incorporated into neutral planar lipid bilayers, they promoted voltage-gated channels. The concentration- and voltage-dependences of the ionic conductances induced by these peptides were studied in macroscopic current-voltage experiments. Single-channel measurements showed that whilst SA IV developed non-integral multi-open states similar to those induced by alamethicins, but with faster kinetics, the shorter analogue, HA V promoted much smaller-sized conducting aggregates in agreement with macroscopic conductance data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05886.x
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  • 6
    Electronic Resource
    Electronic Resource
    Some biochemical properties of an acyclic oligonucleotide analogue. A plausible ancestor of the DNA? (1993)
    Springer
    Origins of life and evolution of the biospheres 23 (1993), S. 91-103 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract As acyclic oligonucleotides have been suggested as a primitive model of DNA or RNA in prebiotic times, we compared some biochemical properties of these analogues to that of natural ones. Firstly, an acyclic analogue of deoxyribonucleoside triphosphates was tested as a potential substrate of enzymes intervening in nucleic acids synthesis. GlyTTP, a dTTP analogue with a missing 2′-methylene group is notaccepted as a substrate by either DNA polymerase or deoxynucleotidyl terminal transferase (TdT). Secondly, themodified dodecathymidylate (GlyT)12, the racemic acyclic sugar analogue of (dT)12, proved to be anefficient primer for DNA polymerase and TdT, though the associative properties of (GlyT)12 are very weak as shown by UV spectroscopy in phosphate buffer without magnesium chloride. But (GlyT)12 has the advantage to be 500-times more stable against hydrolysis by snake venom phosphodiesterase than the corresponding oligothymidylate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01581874
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  • 7
    Electronic Resource
    Electronic Resource
    Chiral versus chemical evolutions and the appearance of life (1984)
    Springer
    Origins of life and evolution of the biospheres 14 (1984), S. 433-437 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The need is emphasized for a common investigation of chemical and configurational evolutions with regard to the major chiral biomolecules as a whole and some experimental lines are developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00933688
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  • 8
    Electronic Resource
    Electronic Resource
    Polycondensation d'acides α-aminés par des systèmes iode-phosphites en présence de pyridine ou d'imidazole (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 2829-2835 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of free α-amino acids with a pair of reagents-an oxidizing agent (iodine) and a reducing agent (phosphonic acid esters)-was achieved in organic medium in the presence of pyridine or imidazole. A standard procedure leading to optically pure polypeptides with degrees of polymerization up to 50 could be established. Polymeric material was also obtained with a dipeptide as monomer. Some preliminary polymerizations with polyfunctional reagents such as poly(4-vinylpyridine), cyclodiphosphites, or polyphosphites were performed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021791202
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  • 9
    Electronic Resource
    Electronic Resource
    Reexamination of the Michelson reaction leading to poly(glycerol phosphate). Its functionalization (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 2379-2390 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fractionation of the products obtained by the Michelson polyaddition of glycerol 2-phosphate with diphenyl phosphate chloride gives a definite poly(glycerol phosphate) (PGP) of a molecular weight of about 1000. The exact structure was determined by 31P NMR spectra from which the existence of a random copolymer containig 1,3- and 1,2-PGP sequences can be inferred. The free hydroxyl groups of PGP were grafted with a 1-thymineacetic acid derivative to an extent of about 40% as determined by 1H NMR.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930921
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  • 10
    Electronic Resource
    Electronic Resource
    Side chain-backbone hydrogen bonds in peptides containing glutamic acid residues (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 1293-1296 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180518
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