Conformations of helical Aib peptides containing a pair of l‐amino acid and d‐amino acid |
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| Authors: | Yosuke Demizu Yu‐u Yabuki Mitsunobu Doi Yukiko Sato Masakazu Tanaka Masaaki Kurihara |
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| Institution: | 1. Division of Organic Chemistry, National Institute of Health Sciences, , Tokyo, 158‐8501 Japan;2. Osaka University of Pharmaceutical Sciences, , Osaka, 569‐1094 Japan;3. Graduate School of Biomedical Sciences, Nagasaki University, , Nagasaki, 852‐8521 Japan |
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| Abstract: | A pair of l ‐leucine (l ‐Leu) and d ‐leucine (d ‐Leu) was incorporated into α‐aminoisobutyric acid (Aib) peptide segments. The dominant conformations of four hexapeptides, Boc‐l ‐Leu‐Aib‐Aib‐Aib‐Aib‐l ‐Leu‐OMe (1a), Boc‐d ‐Leu‐Aib‐Aib‐Aib‐Aib‐l ‐Leu‐OMe (1b), Boc‐Aib‐Aib‐l ‐Leu‐l ‐Leu‐Aib‐Aib‐OMe (2a), and Boc‐Aib‐Aib‐d ‐Leu‐l ‐Leu‐Aib‐Aib‐OMe (2b), were investigated by IR, 1H NMR, CD spectra, and X‐ray crystallographic analysis. All peptides 1a,b and 2a,b formed 310‐helical structures in solution. X‐ray crystallographic analysis revealed that right‐handed (P) 310‐helices were present in 1a and 1b and a mixture of right‐handed (P) and left‐handed (M) 310‐helices was present in 2b in their crystalline states. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd. |
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| Keywords: | α ‐aminoisobutyric acid amino acids peptide helical structure X‐ray crystallography |
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