Source Year: 1997

A peroxidase (EC 1.11.1.1) was isolated and purified from strips of bark of H. brasiliensis (clone RRIM 600). A positive correlation was observed between peroxidase activity and rubber yield per tapping. A high level of peroxidase activity was found in newly excised bark strips. The peroxidase converted phenols isolated from the C-serum fraction of centrifuged latex to polyphenolic forms. The peroxidase was purified to homogeneity by size exclusion, ion exchange and affinity chromatography. Gel filtration chromatography and SDS-PAGE indicated that the peroxidase was composed of a single polypeptide of MW 50 000. The enzyme had a pI of 3.5. The Km values for o-dianisidine and H2O2 were 20 and 18.6 mm, respectively ; the Ki values for KCN and NaN3 for these substrates were 10mm and 2.7mm, respectively. The possible role of the ethylene-inducible bark peroxidase in latex coagulation is discussed.