关于碳酸酐酶作用机制的13-C核磁共振研究。
13-C nuclear magnetic resonance studies on the mechanism of action of carbonic anhydrase.
作者信息
Yeagle P L, Lochmüller C H, Henkens R W
出版信息
Proc Natl Acad Sci U S A. 1975 Feb;72(2):454-8. doi: 10.1073/pnas.72.2.454.
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.
已利用碳-13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）的结合情况。已确定了两个碳酸氢盐结合位点。一个位点松散地结合碳酸氢盐，抑制对硝基苯乙酸活性，必定是碳酸氢盐底物结合位点；另一个位点紧密结合碳酸氢盐，无抑制作用，发挥着其他作用。碳酸氢盐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，而另一个碳酸氢盐则结合在金属的外配位球中。有人提出，脱水过程是通过直接与金属中心配位的HCO₃⁻进行的，而外层球碳酸氢盐则促进具有催化重要性的质子转移。
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