Kinetics of the oxidation of reduced Cu,Zn-superoxide dismutase by peroxymonocarbonate. Free Radic Biol Med 2012 Aug 01;53(3):589-94
Date
05/10/2012Pubmed ID
22569304Pubmed Central ID
PMC3408790DOI
10.1016/j.freeradbiomed.2012.04.029Scopus ID
2-s2.0-84863516911 (requires institutional sign-in at Scopus site) 20 CitationsAbstract
Kinetic evidence is reported for the role of the peroxymonocarbonate, HOOCO(2)(-), as an oxidant for reduced Cu,Zn-superoxide dismutase-Cu(I) (SOD1) during the peroxidase activity of the enzyme. The formation of this reactive oxygen species results from the equilibrium between hydrogen peroxide and bicarbonate. Recently, peroxymonocarbonate has been proposed to be a key substrate for reduced SOD1 and has been shown to oxidize SOD1-Cu(I) to SOD1-Cu(II) much faster than H(2)O(2). We have reinvestigated the kinetics of the reaction between SOD1-Cu(I) and HOOCO(2)(-) by using conventional stopped-flow spectrophotometry and obtained a second-order rate constant of k=1600±100M(-1)s(-1) for SOD1-Cu(I) oxidation by HOOCO(2)(-). Our results demonstrate that peroxymonocarbonate oxidizes SOD1-Cu(I) to SOD1-Cu(II) and is in turn reduced to the carbonate anion radical. It is proposed that the dissociation of His61 from the active site Cu(I) in SOD-Cu(I) contributes to this chemistry by facilitating the binding of larger anions, such as peroxymonocarbonate.
Author List
Ranguelova K, Ganini D, Bonini MG, London RE, Mason RPMESH terms used to index this publication - Major topics in bold
AnimalsCarbonates
Catalytic Domain
Cattle
Kinetics
Models, Molecular
Oxidants
Oxidation-Reduction
Reactive Oxygen Species
Superoxide Dismutase
Superoxide Dismutase-1
