Stimson E R, Meinwald Y C, Scheraga H A
Biochemistry. 1979 May 1;18(9):1661-71. doi: 10.1021/bi00576a005.
By using 13C enrichment in [Leu5]-enkephalin, it has been possible to improve the assignment of carbonyl resonances in the nuclear resonance spectrum and to remove some of the ambiguities in the derived phi and chi dihedral angles, thereby providing information about the conformation of this molecule in solution. The combined use of 13C and 1H nuclear magnetic resonance experiments leads to the conclusion that [Leu5]0enkephalin contains a type I beta bend at residues Gly3-Phe4 in dimethyl-d6 sulfoxide (Me2SO0d6) solution. Furthermore, the side chains of Tyr1, Phe4, and Leu5 exist predominantly in one conformation (tg-) in this solvent. A comparison is made between the conformation found in Me2SO-d6 and those determined by X-ray diffraction and conformational energy calculations.
通过在[亮氨酸5] - 脑啡肽中使用13C富集，已能够改善核磁共振谱中羰基共振的归属，并消除推导的φ和χ二面角中的一些模糊性，从而提供有关该分子在溶液中构象的信息。13C和1H核磁共振实验的联合使用得出结论，在二甲基-d6亚砜（Me2SO-d6）溶液中，[亮氨酸5] - 脑啡肽在残基Gly3 - Phe4处含有I型β转角。此外，在这种溶剂中，Tyr1、Phe4和Leu5的侧链主要以一种构象（tg-）存在。对在Me2SO-d6中发现的构象与通过X射线衍射和构象能量计算确定的构象进行了比较。
