Shahangian S, Hager L P
J Biol Chem. 1981 Jun 25;256(12):6034-40.
Chloroperoxidase catalyzes the dismutation of chlorite-forming chloride, chlorine dioxide, chlorate, and oxygen as products. The yields of chlorine dioxide are variable because chloroperoxidase also catalyzes the decomposition of this compound and, in addition, moderate concentrations of chlorine dioxide inactivate the enzyme. Chloride, chlorate, and oxygen are the products of the decomposition of chlorine dioxide. The optimum pH for the enzymic of decomposition of both chlorite and chlorine dioxide is approximately pH 2.75. At this pH, 1 mole of chlorine dioxide is dismutated to 0.3 mole of chloride, 0.7 mol of chlorate, and 0.17 mole of oxygen. At the same pH, the complete decomposition of 1 mole of chlorite yields 0.4 mole of chloride, 0.6 mole of chlorate, and 0.13 mole of oxygen. During the inactivation of chloroperoxidase by chlorine dioxide, the Soret absorption band of the native enzyme is completely lost, and the enzyme becomes chlorinated. Kinetic parameters for the chlorite reaction have been determined. The Km value for chlorite obtained from various kinetic plots was about 10 mM. The catalytic rate constant for the formation of chlorine dioxide from chlorite was about 70,000 s-1.
氯过氧化物酶催化亚氯酸盐的歧化反应，生成氯离子、二氧化氯、氯酸盐和氧气作为产物。二氧化氯的产量各不相同，因为氯过氧化物酶也催化该化合物的分解，此外，中等浓度的二氧化氯会使该酶失活。氯离子、氯酸盐和氧气是二氧化氯分解的产物。亚氯酸盐和二氧化氯酶促分解的最适pH约为2.75。在此pH下，1摩尔二氧化氯歧化为0.3摩尔氯离子、0.7摩尔氯酸盐和0.17摩尔氧气。在相同pH下，1摩尔亚氯酸盐完全分解生成0.4摩尔氯离子、0.6摩尔氯酸盐和0.13摩尔氧气。在二氧化氯使氯过氧化物酶失活的过程中，天然酶的Soret吸收带完全消失，且该酶被氯化。已测定了亚氯酸盐反应的动力学参数。从各种动力学曲线得到的亚氯酸盐的Km值约为10 mM。由亚氯酸盐生成二氧化氯的催化速率常数约为70000 s-1。
