title: Heme destruction, the main molecular event during the peroxide-mediated inactivation of chloroperoxidase from Caldariomyces fumago.
abstract: Heme peroxidases are subject to a mechanism-based oxidative inactivation. During the catalytic cycle, the heme group is activated to form highly oxidizing species, which may extract electrons from the protein itself. In this work, we analyze changes in residues prone to oxidation owing to their low redox potential during the peroxide-mediated inactivation of chloroperoxidase from Caldariomyces fumago under peroxidasic catalytic conditions. Surprisingly, we found only minor changes in the amino acid content of the fully inactivated enzyme. Our results show that tyrosine residues are not oxidized, whereas all tryptophan residues are partially oxidized in the inactive protein. The data suggest that the main process leading to enzyme inactivation is heme destruction. The molecular characterization of the peroxide-mediated inactivation process could provide specific targets for the protein engineering of this versatile peroxidase.
authors.affiliation: Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, Mexico. maa@ibt.unam.mx
authors.forename: Marcela
authors.initials: M
authors.lastname: Ayala
authors.forename: Cesar V
authors.initials: CV
authors.lastname: Batista
authors.forename: Rafael
authors.initials: R
authors.lastname: Vazquez-Duhalt
mesh_terms: D001203:Ascomycota / Q000201:enzymology*; D002711:Chloride Peroxidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004789:Enzyme Activation / Q000187:drug effects; D006418:Heme / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D015202:Protein Engineering
chemical_list: D006418:Heme; D006861:Hydrogen Peroxide; D002711:Chloride Peroxidase