Recycling of the high valence States of heme proteins by cysteine residues of THIMET-oligopeptidase.
The peptidolytic enzyme THIMET-oligopeptidase (TOP) is able to act as a reducing agent in the peroxidase cycle of myoglobin (Mb) and horseradish peroxidase (HRP). The TOP-promoted recycling of the high valence states of the peroxidases to the respective resting form was accompanied by a significant decrease in the thiol content of the peptidolytic enzyme. EPR (electron paramagnetic resonance) analysis using DBNBS spin trapping revealed that TOP also prevented the formation of tryptophanyl radical in Mb challenged by H2O2. The oxidation of TOP thiol groups by peroxidases did not promote the inactivating oligomerization observed in the oxidation promoted by the enzyme aging. These findings are discussed towards a possible occurrence of these reactions in cells.
Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brasil ; Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo Andre, SP, Brasil.
Juliana C
JC
Ferreira
Marcelo Y
MY
Icimoto
Marcelo F
MF
Marcondes
Vitor
V
Oliveira
Otaciro R
OR
Nascimento
Iseli L
IL
Nantes
D055162:Biocatalysis / Q000187:drug effects; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D006420:Hemeproteins / Q000737:chemistry / Q000378:metabolism*; D006735:Horseradish Peroxidase / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D008666:Metalloendopeptidases / Q000378:metabolism*; D015394:Molecular Structure; D009211:Myoglobin / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism*; D010720:Phosphines / Q000494:pharmacology; D055503:Protein Multimerization / Q000187:drug effects; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013053:Spectrophotometry; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism
D003545:Cysteine; D006420:Hemeproteins; D006735:Horseradish Peroxidase; D006861:Hydrogen Peroxide; D008666:Metalloendopeptidases; D009211:Myoglobin; D010544:Peroxidases; D010720:Phosphines; D013438:Sulfhydryl Compounds; C080938:tris(2-carboxyethyl)phosphine; C022510:thimet oligopeptidase