Purification and characterization of α‐3′,4′‐anhydrovinblastine synthase (peroxidase‐like) from Catharanthus roseus (L.) G. Don

Abstract

An H 2 O 2 -dependent enzyme capable of coupling catharanthine and vindoline into α-3′,4′-anhydrovinblastine (AVLB) was purified to apparent homogeneity from Catharanthus roseus leaves. The enzyme shows a specific AVLB synthase activity of 1.8 nkat/mg, and a molecular weight of 45.40 kDa (SDS-PAGE). In addition to AVLB synthase activity, the purified enzyme shows peroxidase activity, and the VIS spectrum of the protein presents maxima at 404, 501 and 633 nm, indicating that it is a high spin ferric heme protein, belonging to the plant peroxidase superfamily. Kinetic studies revealed that both catharanthine and vindoline were substrates of the enzyme, AVLB being the major coupling product.