A study on a novel superoxide dismutase mimic bis(dioxotetraamine) copper(II) complex - kinetics of catalytic dismutation of superoxide anion by pulse radiolysis and solution equilibrium

A mimic of Cu,Zn,SOD has been investigated in detail. Its stability in solu tion has been obtained by the solution equilibrium study of N,N',N",N"-tetr a(2-aminoethyl)-1,1,2,2,-ethanetetraamide with copper ions. The kinetics of catalytic dismutation of superoxide anions by copper(II) complex [Cu-2(H-4 L)] was studied using pulse radiolysis. The rate constant of catalytic dism utation of O-.(2)- was determined to be k(cat) = 2.81 x 10(8) (pH = 7.8) an d 1.63 x 10(8) mol(-1) dm(3) s(-1) (pH = 8.3) and the mechanism of catalyti c dismutation of O-.(2)- was suggested. The k(cat) values have been compare d with those of other Cu2Zn2SOD (SOD = superoxide dismutase) mimics. The ex perimental results show that the novel mimic exhibits high activity and sta bility at about pH = 7.8. (C) 1999 Elsevier Science Inc. All rights reserve d.