人类血小板中的碳酸酐酶。
Carbonic anhydrase in human platelets.
作者信息
Siffert W, Gros G
出版信息
Biochem J. 1984 Feb 1;217(3):727-30. doi: 10.1042/bj2170727.
The carbonic anhydrase activity of human platelets was investigated by measuring the kinetics of CO2 hydration in supernatants of platelet lysates by using a pH stopped-flow apparatus. An average carbonic anhydrase concentration of 2.1 microM was determined for pellets of human platelets. Analysis of the kinetic properties of this carbonic anhydrase yielded a Km value of 1.0 mM, a catalytic-centre activity kcat. of 130000 s-1 and an inhibition constant Ki towards ethoxzolamide of 0.3 nM. From these values, CO2 hydration inside platelets is estimated to be accelerated by a factor of 2500. When platelet lysates were subjected to affinity chromatography, only the high-activity carbonic anhydrase II could be eluted from the affinity column, whereas the carbonic anhydrase isoenzyme I, which is known to occur in high concentrations in human erythrocytes, appeared to be absent.
利用pH停流装置，通过测量血小板裂解液上清液中CO2水合动力学，对人血小板的碳酸酐酶活性进行了研究。测定人血小板沉淀中碳酸酐酶的平均浓度为2.1 microM。对该碳酸酐酶的动力学性质分析得出，Km值为1.0 mM，催化中心活性kcat为130000 s-1，对乙氧唑胺的抑制常数Ki为0.3 nM。根据这些值，估计血小板内的CO2水合加速了2500倍。当血小板裂解液进行亲和层析时，只有高活性的碳酸酐酶II能从亲和柱上洗脱下来，而在人红细胞中高浓度存在的碳酸酐酶同工酶I似乎不存在。
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