Operational stability of catalase and its conjugates with aldehyde dextrans and superoxide dismutase
Eremin, A.N.; Litvinchuk, A.V.; Metelitsa, D.I.
Biokhimiia 61(4): 664-679
1996
ISSN/ISBN: 0320-9725 PMID: 8724785 Document Number: 465533
Conjugates of catalase, superoxide dismutase (SOD), and both enzymes with aldehyde dextrans have been synthesized in aqueous media and surfactant microemulsions in heptane. The catalytic activities of catalase and its conjugates are characterized by first-order rate constants of H-2O-2 (50 mM) consumption in successive cycles of the use of the biocatalysts. Rate constants for the inactivation of catalase and its conjugates by hydrogen peroxide (k-in) and rate constants for the interaction of catalase complex I with H-2O-2 (k-2) were determined simultaneously from full kinetic curves of H-2O-2 consumption in l/ln((H-2O-2)-0/(H-2O-2)-t) versus l/t coordinates. Values of k-in and k-2 were determined for different conditions of the catalase reaction at various concentrations of the biocatalysts and hydrogen peroxide and in successive cycles of the use of the biocatalysts for H-2O-2 decomposition. The utility of the kinetic parameters k-in and k-2 for characterizing the inactivation of catalase and its conjugates and their reactivity in catalase reactions is demonstrated. The mutual influence of catalase and SOD on their operational stabilities in enzymatic reactions of H-2O-2 decomposition is discussed. The conjugation of catalase with aldehyde dextrans and SOD in microemulsions enhances the stabilities of both enzymes.