13-C nuclear magnetic resonance studies on the mechanism of action of carbonic anhydrase.
13-C nuclear magnetic resonance studies on the mechanism of action of carbonic anhydrase.
复制标题
13-C核磁共振研究碳酸酐酶的作用机制。
DOI：
10.1073/pnas.72.2.454
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发表时间：
1975
影响因子：
11.1
通讯作者：
Robert W. Henkens
中科院分区：
文献类型：
--
作者：
P. Yeagle;C. Lochmuller;Robert W. Henkens
用13-C核磁共振研究了底物碳酸氢盐与牛钴碳酸酐酶（碳酸水解酶，EC 4.2.1.1）的结合。已经确定了碳酸氢盐的两个结合位点。一个松散地结合碳酸氢根，抑制对硝基苯基乙酸酯活性，并且必须是碳酸氢根底物结合位点;另一个紧密地结合碳酸氢根，是非抑制性的，并且起另一种作用。碳酸氢盐的碳原子的自旋晶格弛豫时间表明底物碳酸氢盐直接与酶的金属中心结合，而另一个碳酸氢盐结合在金属的外配位层中。有人提出，脱水进行通过HCO-3负直接协调的金属中心，而外层碳酸氢盐促进催化重要的质子转移。
Binding of the substrate, bicarbonate, to bovine cobalt carbonic anhydrase (carbonate hydrolyase, EC 4.2.1.1) has been studied with 13-C nuclear magnetic resonance. Two binding sites for bicarbonate have been identified. One loosely binds bicarbonate, inhibits p-nitrophenyl acetate activity, and must be the bicarbonate substrate binding site; the other tightly binds bicarbonate, is noninhibitory, and plays another role. Spinlattice relaxation times for the carbon atom of bicarbonate indicate that the substrate bicarbonate is bound directly to the metal center of the enzyme, while the other bicarbonate is bound in the outer coordination sphere of the metal. It is proposed that dehydration proceeds via HCO-3 minus coordinated directly to the metal center, while the outer sphere bicarbonate facilitates catalytically important proton transfers.