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The effect of homologos amini acid replacement on the conformation of oligopeptides. III. CD studies on co‐oligopeptides of methionine and valine or methionine and glycine in organic solution
Author(s) -
Naider F.,
Becker J. M.,
Ribeiro A.,
Goodman M.
Publication year - 1978
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1978.360170914
Subject(s) - random hexamer , methionine , valine , chemistry , residue (chemistry) , oligopeptide , stereochemistry , amino acid , glycine , dimer , peptide , crystallography , organic chemistry , biochemistry
A conformational analyis of co‐ologopeptides containing methionine and valine or methionine and glycine was carried out using circular dichrosim. The oligopeptides containing valine and methionine (dimer to hexamer) are disorder in hexafluoropropane diol·0.5 H 2 O and trimethyl phospate but become helical in trifluoroethanol at the heptamer. The CD spectra for hesamers and heptamers containing methionine or methionine and one valine give evidience that one valyl residue can be inserted into these peptides wothout affecting their secondry structure. Co‐oligomethionines. The effect of a glycyl residue are generally less ordered than the analogous homo‐oligomethionines. The effect of a glycl residue on the structure of the longer oligopeptides depends on its position in the chain. When inserted in the center of a hexamer or heptamer, the single glycyl residue destabilizes the ordered secondry structures in solution. Finally, evidence is presented that the CD patterns observed for various pentamers and hexamers are consistent with some order at these chain lenghts.