Chen Y, Pitzenberger S M, Garsky V M, Lumma P K, Sanyal G, Baum J
Chemistry Department, Rutgers University, Piscataway, New Jersey 08854.
Biochemistry. 1991 Dec 17;30(50):11625-36. doi: 10.1021/bi00114a004.
The snake venom protein echistatin is a potent inhibitor of platelet aggregation. The inhibitory properties of echistatin have been attributed to the Arg-Gly-Asp sequence at residues 24-26. In this paper, sequence-specific nuclear magnetic resonance assignments are presented for the proton resonances of echistatin in water. The single-chain protein contains 49 amino acids and 4 cystine bridges. All of the backbone amide, C alpha H, and side-chain resonances, except for the eta-NH of the arginines, have been assigned. The secondary structure of the protein was characterized from the pattern of nuclear Overhauser enhancements, from the identification of slowly exchanging amide protons, from 3JC alpha H-NH coupling constants, and from circular dichroism studies. The data suggest that the secondary structure consists of a type I beta-turn, a short beta-hairpin, and a short, irregular, antiparallel beta-sheet and that the Arg-Gly-Asp sequence is in a flexible loop connecting two strands of the distorted antiparallel beta-sheet.
蛇毒蛋白echistatin是一种有效的血小板聚集抑制剂。echistatin的抑制特性归因于其24 - 26位残基处的Arg-Gly-Asp序列。本文给出了echistatin在水中质子共振的序列特异性核磁共振归属。该单链蛋白包含49个氨基酸和4个胱氨酸桥。除精氨酸的η-NH外，所有主链酰胺、CαH和侧链共振均已归属。通过核Overhauser效应增强模式、缓慢交换酰胺质子的鉴定、3JCαH-NH耦合常数以及圆二色性研究对该蛋白的二级结构进行了表征。数据表明其二级结构由一个I型β-转角、一个短β-发夹和一个短的、不规则的反平行β-折叠组成，且Arg-Gly-Asp序列位于连接扭曲反平行β-折叠两条链的柔性环中。
