摘要:

AbstractThe synthesis of the following oligo‐ and co‐oligopeptides by the liquid‐phase method is described: (L‐Met)15(I), [L‐Glu(OBzl)]20(II), (L‐Val)8‐Gly (IV), (L‐Ile)8‐Gly (V), (L‐Ile)4‐Gly‐(L‐Ile)4(VI), (L‐Ile)4‐Pro‐(L‐Ile)4(VII), (L‐Met)5‐L‐Pro‐(L‐Met)5(VIII), [L‐Glu(OBzl)]7‐L‐Pro‐[L‐Glu(OBzl)]7(IX). The oligomers are covalently bound to bifunctional polyethylene glycol (PEG) and monofunctional PEG‐M ofMr5 × 103−2 × 104. Analytical controls were carried out after each step of synthesis in order to ensure quantitative coupling yields. All products could be obtained in high purity as indicated by amino acid analysis, thin‐layer chromatography and chiroptical methods. The solubility of the oligomers was strongly enhanced by the presence of the C‐terminal PEG group, enabling conformational investigations in a variety of solvents. A significant relationship between conformation and physicochemical properties of the oligopeptides was observed. Oligomers with tendencies to adopt α‐helical (I, II) or unordered structures (VI–IX) showed no pronounced change in solubility or coupling kinetics during chain elongation, whereas the onset of a β‐structure (IV, V) was paralleled by a drastic decrease in solubility and reactivity of the terminal amino groups. Most notably, the insertion of a proline or glycine in the middle of a β‐forming peptide chain (VI, VII) resulted in a considerable increase in solubility compared to the corresponding homo‐oligomers. The impact of the conformational properties of a peptide chai

ISSN:0006-3525    

DOI:10.1002/bip.1980.360190112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe sequential copolypeptides (Lys‐Phe‐Lys)nand (Lys2‐Phe‐Lys)nand a series of related random copolypeptides were investigated with respect of their ability to adopt the α‐helix or β‐conformation. Conformational transitions were induced by increasing the pH or by addition of NaClO4or methanol and were observed by recording the CD spectra. In contrast to the respective alternating copolypeptide (Phe‐Lys)nwith its strong tendency for the β‐structure reported previously, (Lys‐Phe‐Lys)ncan adopt either secondary structure, whereas (Lys2‐Phe‐Lys)nstrongly favors the α‐helix. Together with the random copolypeptides, whose composition varied from 20 to 50 mol % phenylalanine and whose average molecular weights ranged from 10,000 to 90,000, the influence of the phenylalanine content and of the chain length on conformational stability and the rotatory strength of the respective seconda

ISSN:0006-3525    

DOI:10.1002/bip.1980.360190113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe conformational analysis of the CD spectrum is reported for the synthetic and membrane‐modifying nonadecapeptide analog of alamethicinN‐t‐Boc‐(Aib‐L‐Ala)5‐Gly‐Ala‐Aib‐Pro‐Ala‐Aib‐Aib‐Glu(OBzl)‐ Gln‐OMe. The CD data are evaluated according to three different methods and are discussed with respect to those obtained from natural alamethicin and suitable models such asN‐t‐Boc‐(Aib‐L‐Ala)7‐OPOE, fragments of the synthetic nonadecapeptide, and the hexadecapeptideN‐t‐Boc‐(Aib‐L‐Ala)5‐Pro‐Ala‐Aib‐Aib‐Glu(OBzl)‐Gln‐OMe. The synthetic nonadecapeptide with the longer helical region exhibits membrane activities comparable to those of alamethi

ISSN:0006-3525    

DOI:10.1002/bip.1980.360190114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.1980.360190115

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.1980.360190101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY