Some kinetic properties of polyphenol oxidase obtained from various Salvia species (Salvia viridis L., Salvia virgata Jacq. and Salvia tomentosa Miller)

Abstract

Polyphenol oxidase (PPO) was partially purified by (NH4)(2)SO4 precipitation followed by dialysis from different organs of Salvia species (Salvia virgata Jacq., Salvia viridis L. and Salvia tomentosa Miller). Polyphenol oxidase activity was measured spectrophotometrically at 420 nm using catechol as a substrate. V-max, K-M and V-max/K-M values for polyphenol oxidase activity from different organs of Salvia species were determined. S. tomentosa Miller was the species with the highest PPO activity, followed by S. virgata Jacq and S. viridis L. S. tomentosa Miller was the most suitable Salvia species for dark-tea preparations because of the highest V-max/K-M values. The effects of various inhibitors on the reaction catalysed by the enzyme were tested and calculated I-50 values, reduced the enzyme activity by 50%. The most effective inhibitor was L-cysteine followed by ascorbic acid. Activation energies, E-a, were determined from Arrhenius equation.