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Journal Article 
Operational stability of catalase and its conjugates with aldehyde dextrans and superoxide dismutase 
Eryomin, AN; Litvinchuk, AV; Metelitza, DI 
Biochemistry (Moscow)
ISSN: 0006-2979
EISSN: 1608-3040 
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 H2O2 (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 H2O2 (k(2)) were determined simultaneously from full kinetic curves of H2O2 consumption in 1/ln([H2O2](0)/[H2O2](t)) versus 1/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 H2O2 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 H2O2 decomposition is discussed. The conjugation of catalase with aldehyde dextrans and SOD in microemulsions enhances the stabilities of both enzymes. 
catalase; superoxide dismutase; aldehyde dextrans; enzyme conjugates; antioxidant complex; suicidal enzymes; operational stability