ESR characterization and kinetics of the enzymatically obtained M(II)-dobutamine-o-semiquinone system

Dobutamine is a synthetic catecholamine used in the treatment of different cardiac pathologies associated with organic heart diseases, myocardial infarction and cardiac surgery. The ESR spectra of M2+-o-semiquinone radicals, obtained by the oxidation of dobutamine . HCl with horseradish peroxidase and hydrogen peroxide in the presence of several bivalent metal ions of IIA (Mg, Ca, Sr, Ba) and IIB (Zn, Cd) groups, have been reported. ESR experimental spectra have been simulated and completely characterized. The dependence of the proton hyperfine coupling constant values on the complexing ion radius has been discussed together with the differences in the radical concentrations. Furthermore, the formation and decay kinetics of Zn2+-dobutamine-o-semiquinone have been analyzed at varying H2O2 concentrations, and the corresponding kinetic constants have been calculated.