Premium
Stereochemistry of α‐aminoisobutyric acid peptides in solution: Conformations of decapeptides with a central triplet of contiguous L ‐amino acids
Author(s) -
Balaram Hemalatha,
Sukumar M.,
Balaram P.
Publication year - 1986
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.360251112
Subject(s) - chemistry , folding (dsp implementation) , solvent , amino acid , stereochemistry , hydrogen bond , helix (gastropod) , crystallography , peptide , molecule , organic chemistry , biochemistry , ecology , snail , electrical engineering , biology , engineering
The decapeptides Boc‐Aib‐ L ‐Val‐Aib‐Aib‐( L ‐Val) 3 ‐Aib‐ L ‐Val‐Aib‐OMe and Boc‐Aib‐ L ‐Leu‐Aib‐Aib‐( L ‐Leu) 3 ‐Aib‐ L ‐Leu‐Aib‐OMe have been studied in CDCl 3 and (CD 3 ) 2 SO solutions by 270‐MHz 1 H‐nmr. In CDCl 3 , the presence of eight intramolecularly hydrogen‐bonded NH groups has been established, consistent with a 3 10 ‐helical conformation, for both decapeptides. In (CD 3 ) 2 SO, only seven solvent‐shielded NH groups are observed, supporting either an α‐helical conformation or a partially unfolded 3 10 ‐helix. Ir studies provided supporting evidence for intramolecularly hydrogen‐bonded structures in CHCl 3 , while CD studies suggest helical conformation in both decapeptides in various solvents. CD studies also support helical folding in the C‐terminal hexapeptides. The central triplet of L‐amino acids appears to destabilize 3 10 ‐helical conformations in polar solvents like (CD 3 ) 2 SO.