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Solid-state conformation of diastereomeric -Pro-Pro-(Aib)4 sequences |
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| Authors: | Makoto Oba Nanako Yamagata Mitsunobu Doi Hiroshi Suemune Masaaki Kurihara |
| Affiliation: | a Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan b Division of Organic Chemistry, National Institute of Health Sciences, 1-18-1, Kamiyoga, Setagaya, Tokyo 158-8501, Japan c Osaka University of Pharmaceutical Sciences, Osaka 569-1094, Japan d Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan |
| Abstract: | The crystal structures of two diastereomeric -Pro-Pro-(Aib)4- sequences, Cbz-l-Pro-l-Pro-(Aib)4-OMe (1) and Cbz-d-Pro-l-Pro-(Aib)4-OMe (2), have been determined by X-ray crystallographic analysis. The crystals of the two compounds were characterized by the following parameters: (1) monoclinic, P21, a=10.543 Å, b=8.103 Å, c=22.642 Å, β=97.679, Z=2, R1=0.104, and Rw=0.327; (2) orthorhombic, P212121, a=10.470 Å, b=10.953 Å, c=32.405 Å, Z=4, R1=0.040, and Rw=0.046. In the asymmetric unit of 1, the homochiral l-Pro1-l-Pro2 adopts a polyproline II structure, which induces a left-handed (M) 310-helical structure in the following -(Aib)4- sequence. The preferred conformation of diastereomeric 2, which contains heterochiral d-Pro1-l-Pro2 segments, was similar to that of 1 with differences at the N-terminal d-Pro residue. |
| Keywords: | Peptide Helix X-ray crystallographic analysis Conformation Secondary structure |
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