Purification and Some Properties of Peroxidase from Pericarp of Litchi (Litchi chinensis Sonn.)

Abstract:

Peroxidase(POD) from pericarp of litchi(Litchi chinensis Sonn.) was purified by 12.5-fold and a 1.9% yield using ammonium sulfate, DEAE-Sepharose and Sephadex G-75. The enzyme was determined to be homogenous by SDS-PAGE, which was relatively heat stable with a optimum temperature of 35℃, requiring a time of at least 30 min at 75℃ for 50% loss of the activity. Litchi POD had a optimum pH at 6.5, but it was stable within a range of pH 4.0-8.0. The apparent Km values with guaiacol, catechol and pyrogallol as substrates were 2.75, 12.4 and 12.8 mmol/L at 25oC and pH 7.0，respectively．The presence of Fe³⁺ and Cu²⁺ enhanced POD activity．L-cysteine，citrate acid,FeSO₄，SDS，GSH and ZnS0₄ partially inhibited POD activity,but it was completely inhibited by dithiothreitol and ascorbate.