title: Relative contributions of heart mitochondria glutathione peroxidase and catalase to H(2)O(2) detoxification in in vivo conditions.
abstract: This study was aimed at assessing the relative contributions to H(2)O(2) detoxification by glutathione peroxidase and catalase in the mitochondrial matrix of heart. For this purpose, mitoplasts from rat heart were used in order to minimize contamination with microperoxisomes, and the kinetic rate constants of both enzymatic activities were determined along with a simulation profile. Results show that the contribution of catalase to H(2)O(2) removal in heart mitochondria is not significant, even under strong oxidative conditions, such as those achieved in ischemia-reperfusion and involving extensive glutathione depletion and high H(2)O(2) concentrations. Conversely, maintenance of the steady state levels of H(2)O(2) in the heart mitochondrial matrix seems to be the domain of glutathione peroxidase. It is suggested that the physiological role of the low amounts of catalase found in heart mitochondria is related to its peroxidatic rather than catalatic activity.
authors.affiliation: Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles, USA. fantunes@fc.ul.pt
authors.forename: Fernando
authors.initials: F
authors.lastname: Antunes
authors.forename: Derick
authors.initials: D
authors.lastname: Han
authors.forename: Enrique
authors.initials: E
authors.lastname: Cadenas
mesh_terms: D000818:Animals; D002374:Catalase / Q000502:physiology*; D004072:Digitonin / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008658:Inactivation, Metabolic / Q000502:physiology; D007202:Indicators and Reagents / Q000494:pharmacology; D008297:Male; D008929:Mitochondria, Heart / Q000201:enzymology*; D008956:Models, Chemical; D051381:Rats; D017208:Rats, Wistar
chemical_list: D007202:Indicators and Reagents; D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase; D005978:Glutathione; D004072:Digitonin