One‐Handed Helical Screw Direction of Homopeptide Foldamer Exclusively Induced by Cyclic α‐Amino Acid Side‐Chain Chiral Centers |
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| Authors: | Dr Yosuke Demizu Prof Mitsunobu Doi Dr Masaaki Kurihara Prof Tokumi Maruyama Prof Hiroshi Suemune Prof Masakazu Tanaka |
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| Institution: | 1. National Institute of Health Sciences, Tokyo 158‐8501 (Japan);2. Osaka University of Pharmaceutical Sciences, Osaka 569‐1094 (Japan);3. Faculty of Pharmaceutical Sciences, Kagawa Campus, Tokushima Bunri University, Kagawa 769‐2193 (Japan);4. Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812‐8582 (Japan);5. Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852‐8521 (Japan), Fax: (81+)?95‐819‐2423 |
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| Abstract: | Chiral cyclic α,α‐disubstituted amino acids, (3S,4S)‐ and (3R,4R)‐1‐amino‐3,4‐(dialkoxy)cyclopentanecarboxylic acids ((S,S)‐ and (R,R)‐Ac5cdOR; R: methyl, methoxymethyl), were synthesized from dimethyl L ‐(+)‐ or D ‐(?)‐tartrate, and their homochiral homoligomers were prepared by solution‐phase methods. The preferred secondary structure of the (S,S)‐Ac5cdOMe hexapeptide was a left‐handed (M) 310 helix, whereas those of the (S,S)‐Ac5cdOMe octa‐ and decapeptides were left‐handed (M) α helices, both in solution and in the crystal state. The octa‐ and decapeptides can be well dissolved in pure water and are more α helical in water than in 2,2,2‐trifluoroethanol solution. The left‐handed (M) helices of the (S,S)‐Ac5cdOMe homochiral homopeptides were exclusively controlled by the side‐chain chiral centers, because the cyclic amino acid (S,S)‐Ac5cdOMe does not have an α‐carbon chiral center but has side‐chain γ‐carbon chiral centers. |
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| Keywords: | amino acids chirality conformation analysis helical structures peptides |
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