Journal of Peptide Science 2010-11-01

Conformations of peptides containing a chiral cyclic α, α-disubstituted α-amino acid within the sequence of Aib residues.

Yosuke Demizu, Masakazu Tanaka, Mitsunobu Doi, Masaaki Kurihara, Haruhiro Okuda, Hiroshi Suemune

Index: J. Pept. Sci. 16(11) , 621-6, (2010)

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Abstract

A single chiral cyclic α,α-disubstituted amino acid, (3S,4S)-1-amino-(3,4-dimethoxy)cyclopentanecarboxylic acid [(S,S)-Ac(5)c(dOM)], was placed at the N-terminal or C-terminal positions of achiral α-aminoisobutyric acid (Aib) peptide segments. The IR and (1)H NMR spectra indicated that the dominant conformations of two peptides Cbz-[(S,S)-Ac(5)c(dOM)]-(Aib)(4)-OEt (1) and Cbz-(Aib)(4)-[(S,S)-Ac(5)c(dOM)]-OMe (2) in solution were helical structures. X-ray crystallographic analysis of 1 and 2 revealed that a left-handed (M) 3(10)-helical structure was present in 1 and that a right-handed (P) 3(10)-helical structure was present in 2 in their crystalline states.Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.