Purification and enzymatic properties of a peroxidase from leaves of Phytolacca dioica L. (Ombú tree)

Abstract

A peroxidase (PD-cP; 0.47 mg/100 g leaves) was purified from autumn leaves of Phytolacca dioica L. and characterized. PD-cP was obtained by acid precipitation followed by gel-filtration and cation exchange chromatography. Amino acid composition and N-terminal sequence of PD-cP up to residue 15 were similar to that of Spinacia oleracea (N-terminal pairwise comparison showing four amino acid differences). PD-cP showed a molecular mass of approx. 36 kDa by SDS-PAGE, pH and temperature optima at 3.0 and 50.0°C, respectively and seasonal variation. The Michaelis-Menten constant (KM) for H2O2 was 5.27 mM, and the velocity maximum (Vmax) 1.31 nmol min-1, while the enzyme turnover was 0.148 s-1. Finally, the presence of Ca2+ and Mg2+ enhanced the PD-cP activity, with Mg2+ 1.4-fold more effective than Ca2+.