Abstract:

Electrophoresis-purity peroxidase (POD) was extracted and purified from Ipomoea aquatica Forsk. through
ammonium sulfate precipitation, DEAE-Sepharose and Superdex-200 chromatography. The specific activity of the purified
peroxidase was 35 972.96 U/mg and the yield was 211.07 U/g with a recovery rate of 12.21% and a purification fold of
168.48. Its molecular mass was around 42.7 kD as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis
(SDS-PAGE). Besides, the POD with the optimal temperature and pH of 40 ℃ and 6, respectively, was relatively stable
in the temperature range of 20–50 ℃ and pH range of 5–8. This enzyme showed a Km value of 18.32 mmol/L towards the
substrate hydrogen peroxide. In addition, the POD was found to be activated by NaCl, urea, Zn2+and Mg2+ but inhibited by
SDS, KSCN, ascorbic acid (AsA), Ba2+, Mn2+, Fe2+, methanol, ethanol, n-butyl alcohol and isopropanol, and completely
inactivated by 0.01 mmol/L AsA.

Key words: Ipomoea aquatica Forsk., peroxidase, isolation and purification, enzyme activity