Reference

Conformational preferences of oligopeptides rich in a-aminoisobutyric acid

Conformational preferences of oligopeptides rich in a-aminoisobutyric acid. I. Observation of a 310/a-helical transition upon sequence permutation. Basu, Gautam; Bagchi, Ken; Kuki, Atsuo (Dep. Chem., Cornell Univ., Ithaca, NY 14853, USA). Biopolymers, 31(14), 1763-74 (English) 1991. CODEN: BIPMAA. ISSN: 0006-3525.Several substances with their cas registry numbers 96402-49-2 and 139881-81-5 may be metioned in this study. DOCUMENT TYPE: Journal CA Section: 34 (Amino Acids, Peptides, and Proteins) Section cross-reference(s): 22 The soln. conformation of peptides rich in a-aminoisobutyric acid (Aib) is a subtle problem, not because of helix/coil transitions, but rather because of a-helical/310-helical competition. A series of peptides contg. 75% Aib has been synthesized that feature identical amino acid compn. but differing sequences; they are sequence permutation isomers. NMR hydrogen-bonding studies reveal that there is a sequence permutation-induced transition between the 2 alternative helical forms within this set. The implications for the design and conformational prediction of helical Aib-rich peptides are discussed. .