Selected Kinetic Properties of Polyphenol Oxidase Extracted from Rosmarinus Officinalis L.

Abstract

Polyphenol oxidase from Rosmarinus officinalis L. (PPO, EC 1:14:18.1) was extracted and partially purified by using (NH₄)₂SO₄ precipitation and dialysis. Stable and highly active PPO extracts were obtained using 0.5% (w/v) PEG and 0.5% (w/v) Triton X-100 in 0.1 M phosphate buffer 7.0. K_M values were found to be as 14.3 mM for catechol. Four isoenzymes of Rosemary PPO were detected by PAGE with DL-dopa substrate. The enzyme was strongly inhibited by dithiotreitol, sodium metasulfite, sodium thiosulfate, ascorbic acid, and L-cysteine. Metal ions Ca⁺⁺, Mg⁺⁺, and Mn⁺⁺ were poor inhibitors of rosemary PPO at 10 Mm.

Keywords:

• Plant polyphenol oxidase
• Rosmarinus officinalis
• Heat inactivation
• pH stability
• Characterization