Premium
1 H‐nmr study of protected methionine homo‐oligopeptides in helix‐supporting environment
Author(s) -
Naider Fred,
Ribeiro Anthony A.,
Goodman Murray
Publication year - 1980
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.1980.360191008
Subject(s) - chemistry , oligopeptide , solvent , chemical shift , helix (gastropod) , proton nmr , stereochemistry , crystallography , peptide , organic chemistry , snail , biology , ecology , biochemistry
1 H‐nmr spectra for a series of Boc‐ L ‐(Met) n ‐OMe ( n = 2–9) homo‐oligopeptides have been observed in the helix‐supporting solvent trifluoroethanol (TFE) at millimolar concentrations. Interfering solvent peaks were eliminated using two decoupling frequencies to selectively remove the methylene and hydroxyl protons of the solvent. Comparisons with specifically α‐deuterated homo‐oligopeptides gave complete assignments of the NH region of the Boc‐Met n ‐OMe oligomers up to the heptapeptide. Analysis of chemical shifts, coupling constants, and temperature dependence of chemical shifts suggests that up to the hexapeptide, similar structures exist in deuterochloroform and TFE. In contrast, nmr parameters at the heptapeptide for several internal residues differ in these solvents. These results suggest that a C 7 to α‐helix transition may occur in TFE as the chain length of the methionine oligopeptides increases.