Abstract:

Electrophoretically pure polyphenol oxidase (PPO) from fresh coriander leaves was obtained through
homogenization, buffer solution extraction, ammonium sulfate precipitation, DEAE-Sepharose ion exchange chromatography
and Superdex-200 gel filtration chromatography. The specific activity of purified PPO was 5 622.95 U/mg with a recovery of
3.90% and a purification factor of 126.08. The molecular weights of this enzyme and its subunits were 111.10 and 55.60 kD,
respectively. It was relatively stable in the range of 25–45 ℃ and pH 6.0–7.0. Its optimum temperature and pH were 37 ℃
and 6.5, respectively. Furthermore, its Km was 4.04 × 10-2 mol/L under the optimum conditions. Its activity was inhibited by
methanol, ethanol, isopropanol, trichloromethan, citric acid and ascorbic acid as well as some metal ions such as Ca2+, Hg2+
and Ba2+, but was activated by Co2+ and Pb2+.

Key words: coriander leaves, polyphenol oxidase, isolation and purification, characterization