title: Comparison of myeloperoxidase and hemi-myeloperoxidase with respect to catalysis, regulation, and bactericidal activity.
abstract: It has been demonstrated previously (P.C. Andrews and N.I. Krinsky (1981) J. Biol. Chem. 256, 4211-4218) that human leukocyte myeloperoxidase, an alpha 2 beta 2 enzyme, can be cleaved by mild reduction and alkylation to an alpha 1 beta 1 structure that we have termed hemi-myeloperoxidase. The native enzyme and hemi-myeloperoxidase have the same specific activity in a Cl--independent peroxidase assay and identical visible spectra under either oxidized or reduced conditions. This paper compares other properties of native and hemi-myeloperoxidase. Both enzymes are inhibited by high concentrations of H2O2 in an identical fashion. Both enzymes showed identical regulation by pH and Cl-. The utilization of Cl-, as assayed by chlorination of diethanolamine, was moderately decreased in hemi-myeloperoxidase. This reduction in chlorination was not reflected in a bactericidal assay, where again, hemi-myeloperoxidase was identical in activity to native myeloperoxidase.
mesh_terms: D001560:Benzidines; D001770:Blood Bactericidal Activity; D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D002712:Chlorides / Q000378:metabolism; D004926:Escherichia coli; D004983:Ethanolamines; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007962:Leukocytes / Q000201:enzymology*; D046911:Macromolecular Substances; D009195:Peroxidase / Q000097:blood*; D010544:Peroxidases / Q000097:blood*
chemical_list: D001560:Benzidines; D002712:Chlorides; D004983:Ethanolamines; D046911:Macromolecular Substances; C020515:N,N,N',N'-tetramethylbenzidine; C020283:diethanolamine; D006861:Hydrogen Peroxide; D010544:Peroxidases; D009195:Peroxidase