Bourne Y, Taylor P, Marchot P
Department of Pharmacology, University of California, San Diego, La Jolla 92093-0636, USA.
Cell. 1995 Nov 3;83(3):503-12. doi: 10.1016/0092-8674(95)90128-0.
The crystal structure of the snake toxin fasciculin, bound to mouse acetylcholinesterase (mAChE), at 3.2 A resolution reveals a synergistic three-point anchorage consistent with the picomolar dissociation constant of the complex. Loop II of fasciculin contains a cluster of hydrophobic residues that interact with the peripheral anionic site of the enzyme and sterically occlude substrate access to the catalytic site. Loop I fits in a crevice near the lip of the gorge to maximize the surface area of contact of loop II at the gorge entry. The fasciculin core surrounds a protruding loop on the enzyme surface and stabilizes the whole assembly. Upon binding of fasciculin, subtle structural rearrangements of AChE occur that could explain the observed residual catalytic activity of the fasciculin-enzyme complex.
蛇毒素束丝菌素与小鼠乙酰胆碱酯酶（mAChE）结合时的晶体结构，在3.2埃分辨率下揭示了一种协同三点锚定，这与该复合物的皮摩尔解离常数一致。束丝菌素的环II包含一簇疏水残基，这些残基与酶的外周阴离子位点相互作用，并在空间上阻碍底物进入催化位点。环I位于峡谷边缘附近的裂缝中，以最大化环II在峡谷入口处的接触表面积。束丝菌素核心围绕着酶表面上的一个突出环，并稳定整个组装体。束丝菌素结合后，AChE会发生细微的结构重排，这可以解释观察到的束丝菌素 - 酶复合物的残余催化活性。
