Peroxidase from Hevea brasiliensis bark: Purification and properties

Abstract

A peroxidase (EC 1,11,1,7) has been isolated and purified from strips of bark from the rubber tree (Hevea brasiliensis). A positive correlation between bark peroxidase level and rubber yield per tapping was observed. High level of peroxidase was found in newly excised bark strips obtained after tapping. 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 indicates that the purified peroxidase is composed of a single polypeptide of M(r) 50 000. The enzyme has a pI of 3.5. The K(m) values for o-dianisidine and H2O2were 20 and 18.6 μM, respectively, and the K(i) values for KCN and NaN3for these substrates were 10 μM and 2.7 mM, respectively. The possible role of the ethylene-inducible bark peroxidase in latex coagulation is discussed.