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The reaction of chloroperoxidase with chlorite and chlorine dioxide.

1981; Elsevier BV; Volume: 256; Issue: 12 Linguagem: Inglês

10.1016/s0021-9258(19)69124-6

1083-351X

Shahram Shahangian, Lowell P. Hager,

Chemical Analysis and Environmental Impact

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 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 K,,, value for chlorite obtained from various kinetic plots was about 10 m ~.The catalytic rate constant for the formation of chlorine dioxide from chlorite was about 70,000 s-'.