催化三位一体
鱼雷
丝氨酸水解酶
化学
立体化学
乙酰胆碱酯酶
活动站点
丝氨酸
四级结构
水解酶
乙酰胆碱受体
羧肽酶
蛋白酵素
酶
生物化学
蛋白质亚单位
基因
受体
作者
Joel L. Sussman,Michal Harel,Felix Frolow,Christian Oefner,Adrian Goldman,Lilly Toker,Israel Silman
出处
期刊:Science
[American Association for the Advancement of Science (AAAS)]
日期:1991-08-23
卷期号:253 (5022): 872-879
被引量:2599
标识
DOI:10.1126/science.1678899
摘要
The three-dimensional structure of acetylcholinesterase from Torpedo californica electric organ has been determined by x-ray analysis to 2.8 angstrom resolution. The form crystallized is the glycolipid-anchored homodimer that was purified subsequent to solubilization with a bacterial phosphatidylinositol-specific phospholipase C. The enzyme monomer is an α/β protein that contains 537 amino acids. It consists of a 12-stranded mixed β sheet surrounded by 14 α helices and bears a striking resemblance to several hydrolase structures including dienelactone hydrolase, serine carboxypeptidase-II, three neutral lipases, and haloalkane dehalogenase. The active site is unusual because it contains Glu, not Asp, in the Ser-His-acid catalytic triad and because the relation of the triad to the rest of the protein approximates a mirror image of that seen in the serine proteases. Furthermore, the active site lies near the bottom of a deep and narrow gorge that reaches halfway into the protein. Modeling of acetylcholine binding to the enzyme suggests that the quaternary ammonium ion is bound not to a negatively charged "anionic" site, but rather to some of the 14 aromatic residues that line the gorge.
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