The kinetic characterization of soybean seedling amine oxidase (SSAO) and the effect of ionic strength and pH on the enzyme activity have been studied, A strong dependence of the activity on the carbon chain length of alpha-omega diamines, peaking at C-8 and at C-5, for K-m and k(c), respectively, was found, The analysis of ionic strength effects on activity showed a high sensitivity of K-m and an insensitivity of K-c to this parameter. This behavior and the different dependence of K-m and k(c) on the carbon chain length suggest a two-stage equilibrium model for the oxidative deamination of polyamines by SSAO. The formation of the first intermediate (complex amine-enzyme) is controlled mainly by ionic interactions and by the structure of the polyamine, while the formation of the second intermediate depends only on the length of the carbon chain of the diamine, The molecular dissociation constants of the system soybean seedling amine oxidase-cadaverine were obtained from the dependence of k(c), K-m, and k(c)/K-m on pH. A mechanism of the initial steps of reaction, involving a two-stage equilibrium model, is proposed.

Kinetic characterization of soybean seedling amine oxidase

DI PAOLO, MARIA LUISA;VIANELLO, FABIO;
1995

Abstract

The kinetic characterization of soybean seedling amine oxidase (SSAO) and the effect of ionic strength and pH on the enzyme activity have been studied, A strong dependence of the activity on the carbon chain length of alpha-omega diamines, peaking at C-8 and at C-5, for K-m and k(c), respectively, was found, The analysis of ionic strength effects on activity showed a high sensitivity of K-m and an insensitivity of K-c to this parameter. This behavior and the different dependence of K-m and k(c) on the carbon chain length suggest a two-stage equilibrium model for the oxidative deamination of polyamines by SSAO. The formation of the first intermediate (complex amine-enzyme) is controlled mainly by ionic interactions and by the structure of the polyamine, while the formation of the second intermediate depends only on the length of the carbon chain of the diamine, The molecular dissociation constants of the system soybean seedling amine oxidase-cadaverine were obtained from the dependence of k(c), K-m, and k(c)/K-m on pH. A mechanism of the initial steps of reaction, involving a two-stage equilibrium model, is proposed.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/117822
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