Division of Organic Chemistry, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya, Tokyo 158-8501, Japan.
J Pept Sci. 2012 Jul;18(7):466-75. doi: 10.1002/psc.2418. Epub 2012 May 22.
A pair of L-leucine (L-Leu) and D-leucine (D-Leu) was incorporated into a-aminoisobutyric acid (Aib) peptide segments. Thedominant 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.
一对 L-亮氨酸（L-Leu）和 D-亮氨酸（D-Leu）被掺入到α-氨基异丁酸（Aib）肽段中。四个六肽 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）和 Boc-Aib-Aib-D-Leu-L-Leu-Aib-Aib-OMe（2b）的优势构象通过红外光谱（IR）、¹H NMR、CD 光谱和 X 射线晶体学分析进行了研究。所有肽 1a、1b 和 2a、2b 在溶液中均形成 3₁₀ 螺旋结构。X 射线晶体学分析表明，在其晶体状态下，1a 和 1b 中存在右手（P）3₁₀ 螺旋，而 2b 中则存在右手（P）和左手（M）3₁₀ 螺旋的混合物。
