Recycling of the High Valence States of Heme Proteins by Cysteine Residues of THIMET-Oligopeptidase

• Grant number: 14/02884-6
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: April 01, 2014
• End date: September 30, 2014
• Field of knowledge: Biological Sciences - Biophysics - Radiology and Photobiology
• Principal Investigator: Iseli Lourenço Nantes Cardoso
• Grantee: Iseli Lourenço Nantes Cardoso
• Host Institution: Centro de Ciências Naturais e Humanas (CCNH). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil

Abstract

The peptidolytic enzyme THIMET-oligopeptidase (TOP) is able to act as a reducing agent in the peroxi-dase 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 inac-tivating oligomerization observed in the oxidation promoted by the enzyme aging. These findings are discussed towards a possible occurrence of these reactions in cells. (AU)