title: Myeloperoxidase inactivation in the course of catalysis of chlorination of taurine.
abstract: Myeloperoxidase (donor: hydrogen-peroxide oxidoreductase, EC 1.11.1.7) was isolated from leukocytes of patients with chronic granulocyte leukemia. In the presence of H2O2 and Cl- at pH 4.0-6.6 the myeloperoxidase catalyses chlorination of taurine to monochloramine taurine and simultaneously undergoes inactivation. The myeloperoxidase inactivation rate depends on the concentration of H2O2 and Cl-: both the initial rate of chlorination and myeloperoxidase inactivation rate increase with increasing concentration of H2O2. However, an increase in concentration of Cl- results in a decrease in enzyme inactivation. At a given H2O2 concentration, myeloperoxidase inactivation is a first order reaction, which implied that the enzyme may react with a substrate a limited number of times.
mesh_terms: D002712:Chlorides; D006801:Humans; D006861:Hydrogen Peroxide; D007700:Kinetics; D007951:Leukemia, Myeloid / Q000201:enzymology; D007962:Leukocytes / Q000201:enzymology; D008433:Mathematics; D009195:Peroxidase / Q000037:antagonists & inhibitors* / Q000097:blood; D010544:Peroxidases / Q000037:antagonists & inhibitors*; D013053:Spectrophotometry; D013654:Taurine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D002712:Chlorides; D013654:Taurine; D006861:Hydrogen Peroxide; D010544:Peroxidases; D009195:Peroxidase