Inhibition of carboxypeptidase A by excess zinc: Analysis of the structural determinants by X-ray crystallography
Inhibition of carboxypeptidase A by excess zinc: Analysis of the structural determinants by X-ray crystallography
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DOI：
10.1016/s0014-5793(96)01412-3
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发表时间：
1997-01-06
期刊：
影响因子：
3.5
通讯作者：
Aviles, FX
中科院分区：
文献类型：
--
作者：
GomezOrtiz, M;GomisRuth, FX;Aviles, FX
胰腺金属羧肽酶被毫摩尔过量的锌和其他外源性和内源性金属蛋白酶共同抑制。我们用1.7埃总分辨率的X射线结晶学分析了过量锌离子抑制的牛羧肽酶A的结构。在这些条件下，观察到第二个锌与酶活性部位结合，建立了一个扭曲的四面体配位络合物，它包括Glu-270(催化的通用碱基)、物质分子、氯离子和氢氧化物离子。这种氢氧化物离子在抑制性和催化性锌离子之间形成了114度的角桥，它们彼此之间的距离为3.3埃。抑制性锌将氢氧化物保持在与先前观察到的活性部位物质分子(W571)几乎相同的位置，并可能扰乱催化过程中底物切割所需的底物定位和立体化学重排。
Pancreatic metallocarboxypeptidases are inhibited by a millimolar excess of zinc together with other exo- and endometalloproteases. We have analyzed the structure of bovine carboxypeptidase A inhibited by an excess of zinc ions using Xray crystallography at 1.7 Angstrom overall resolution. Under these conditions, a second zinc is observed to bind to the enzyme active site, establishing a distorted tetrahedrally coordinated complex which involves Glu-270 (the general base for catalysis), a mater molecule, a chloride ion, and a hydroxide ion. This hydroxide ion forms a 114 degrees angular bridge between the inhibitory and the catalytic zinc ions, which are at a distance of 3.3 Angstrom from one another. The inhibitory zinc holds the hydroxide at nearly the same location as a previously observed active site mater molecule (W571) and probably perturbs the substrate positioning and stereochemical rearrangements required for substrate cleavage during catalysis.