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Aggregation of apolar peptides in organic solvents. Concentration dependence of 1 H‐nmr parameters for peptide NH groups in 3 10 helical decapeptide fragment of suzukacillin
Author(s) -
Iqbal M.,
Balaram P.
Publication year - 1982
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.360210711
Subject(s) - chemistry , intramolecular force , hydrogen bond , intermolecular force , peptide , chemical shift , monomer , crystallography , yield (engineering) , stereochemistry , atmospheric temperature range , molecule , organic chemistry , polymer , biochemistry , materials science , physics , meteorology , metallurgy
Peptide NH chemical shifts and their temperature dependences have been monitored as a function of concentration for the decapeptide, Boc‐Aib‐Pro‐Val‐Aib‐Val‐Ala‐Aib‐Ala‐Aib‐Aib‐OMe in CDCl 3 (0.001–0.06 M ) and (CD 3 ) 2 SO (0.001–0.03 M ). The chemical shifts and temperature coefficients for all nine NH groups show no significant concentration dependence in (CD 3 ) 2 SO. Seven NH groups yield low values of temperature coefficients over the entire range, while one yields an intermediate value. In CDCl 3 , the Aib(1) NH group shows a large concentration dependence of both chemical shift and temperature coefficient, in contrast to the other eight NH groups. The data suggest that in (CD 3 ) 2 SO, the peptide adopts a 3 10 helical conformation and is monomeric over the entire concentration range. In CDCl 3 , the 3 10 helical peptide associates at a concentration of 0.01 M , with the Aib(1) NH involved in an intermolecular hydrogen bond. Association does not disrupt the intramolecular hydrogen‐bonding pattern in the decapeptide.