Oxygen binding to tyrosinase from Streptomyces antibioticus studied by laser flash photolysis
Oxygen binding to tyrosinase from Streptomyces antibioticus studied by laser flash photolysis
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DOI：
10.1021/ja0541128
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发表时间：
2005-12-28
影响因子：
15
通讯作者：
Canters, GW
中科院分区：
文献类型：
--
作者：
Hirota, S;Kawahara, T;Canters, GW
酪氨酸酶催化单酚的羟基化(单酚酶活性)和邻二酚对苯二酚的氧化(二酚酶活性)，并具有双核铜活性中心。用闪光光解方法研究了氧化酪氨酸酶与O2的结合动力学，得到O2结合速率常数KO2=13±3μM-1s-1。小分子，如一氧化碳和对硝基苯酚(底物−类似物抑制剂)，被证明影响氧结合动力学。由kO2的温度依赖关系计算出O2结合限速步骤的活化热为12.8±2.6kcal/mol。
Tyrosinases catalyze theo-hydroxylation of monophenols (monophenolase activity) and the oxidation ofo-diphenols too-quinones (diphenolase activity) and possess a dinuclear copper active site. The O2binding kinetics of oxytyrosinase is studied by flash-photolysis measurements, and the O2binding rate constant (kO2) is obtained askO2= 13 ± 3 μM-1s-1. Small molecules, such as carbon monoxide andp-nitrophenol (a substrate−analogue inhibitor), are demonstrated to affect O2binding kinetics. The activation enthalpy of the rate-limiting step of O2binding is calculated by the temperature dependence ofkO2to be 12.8 ± 2.6 kcal/mol.