Conformations of peptides containing a chiral cyclic α, α‐disubstituted α‐amino acid within the sequence of Aib residues |
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| Authors: | Yosuke Demizu Masakazu Tanaka Mitsunobu Doi Masaaki Kurihara Haruhiro Okuda Hiroshi Suemune |
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| Institution: | 1. Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812‐8582, Japan;2. Division of Organic Chemistry, National Institute of Health Sciences, Tokyo 158‐8501, Japan;3. Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852‐8521, Japan;4. Osaka University of Pharmaceutical Sciences, Osaka 569‐1094, Japan |
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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)‐Ac5cdOM], was placed at the N‐terminal or C‐terminal positions of achiral α‐aminoisobutyric acid (Aib) peptide segments. The IR and 1H NMR spectra indicated that the dominant conformations of two peptides Cbz‐(S,S)‐Ac5cdOM]‐(Aib)4‐OEt ( 1) and Cbz‐(Aib)4‐(S,S)‐Ac5cdOM]‐OMe (2) in solution were helical structures. X‐ray crystallographic analysis of 1 and 2 revealed that a left‐handed (M) 310‐helical structure was present in 1 and that a right‐handed (P) 310‐helical structure was present in 2 in their crystalline states. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. |
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| Keywords: | α ‐aminoisobutyric acid chiral cyclic α α ‐disubstituted amino acid conformational analysis 310‐helix X‐ray diffraction |
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