[Purification and properties of peroxidase from tea leaves]

Purification of fractions of tea leaves peroxidase is described. During ion-exchange chromatography on DEAE- and CM-cellulose peroxidase is eluted into six fractions, differing in their electrophoretic properties. The enzyme showed optimal activity at pH 4.1-5.0, when the enzyme fractions of guaiacol adsorbed on DEAE-cellulose were used as a substrate; in case of enzyme fractions adsorbed on CM-cellulose it was observed within pH range of 5.4-6.2. The dependence curves of the initial rate of the reaction on the substrate concentration were S-shaped in case of the latter fractions. Peroxidase is shown to catalyze the oxidation of tea catechins; its activity is inhibited by the products of their condensation. The catalytic effect of the enzyme on the oxidation of phenolic acids, e.g. chlorogenic, caffeic and gallic, was far stronger than on that of tea catechins, pyrogallol and pyrocatechin. It was established that two fractions of the enzyme possess predominantly the phloroglucinol oxidase activity, whereas the other fractions do not catalyze the oxidation of phloroglucin. The molecular weights of some peroxidase fractions estimated by polyacryl amide gel electrophoresis are 26.000+/-1.100, 45.00+/-1.200 and 50.000+/-1.500.