Kinetic studies of the two-step reactions of H<SUB>2</SUB>O<SUB>2</SUB> with manganese-reconstituted myoglobin

Kinetics and thermodynamics of the reaction of manganese-reconstituted myoglobin (MnMb) with hydrogen peroxide have been investigated by the stopped-flow kinetic technique. The results show evidence of two-step formation of peroxide compound in MnMb. Detailed kinetic investigation provides the complete reaction mechanism of the formation of the peroxide compound. It is observed that the formation of the peroxide compound involves an equilibrium binding step with MnMb and H2O2. The H2O2 bound complex of MnMb undergoes irreversible transformation to the peroxide compound, MnMb-I. The microscopic rate constants, involved during these elementary transformation reactions, have been determined. The detailed thermodynamic investigation of the elementary transformation enables us to construct their energy diagram