Chiang C C, Karle I L, Wieland T
Int J Pept Protein Res. 1982 Nov;20(5):414-20. doi: 10.1111/j.1399-3011.1982.tb03061.x.
The naturally occurring cyclic hexapeptide, cycloamanide A, has only one intramolecular hydrogen bond. It is a 4 leads to 1 type that encompasses the L Phe-L Ala sequence in which the experimentally determined phi, psi values are +54 degrees, -118 degrees and -88 degrees, -4 degrees, respectively. Even though the chirality is L, L, the phi, psi values are characteristic for a D, L beta-bend, Type II'. The conformation of the molecule was established by a crystal structure determination using X-ray diffraction analysis. Cycloamanide A (C33H42N6O6 . 4H2O) crystallizes in space group P2(1)2(1)2(1) with cell parameters a = 13.307(2) A, b = 24.820(4)A and c = 11.231(1)A.
天然存在的环状六肽环蒜氨酸A只有一个分子内氢键。它是一种4到1型的结构，包含L-苯丙氨酸-L-丙氨酸序列，其中实验测定的φ、ψ值分别为+54°、-118°和-88°、-4°。尽管手性是L，L，但φ、ψ值是D，L型II'β-转角的特征值。该分子的构象通过X射线衍射分析的晶体结构测定得以确定。环蒜氨酸A（C33H42N6O6·4H2O）以空间群P2(1)2(1)2(1)结晶，晶胞参数a = 13.307(2) Å，b = 24.820(4) Å，c = 11.231(1) Å。
