PURIFICATION AND CHARACTERIZATION OF ALPHA-3',4'-ANHYDROVINBLASTINE SYNTHASE (PEROXIDASE-LIKE) FROM CATHARANTHUS-ROSEUS (L) DON,G

An H2O2-dependent enzyme capable of coupling catharanthine and vindoli ne into alpha-3',4'-anhydrovinblastine (AVLB) was purified to apparent homogeneity from Catharanthus roseus leaves. The enzyme shows a speci fic AVLB synthase activity of 1.8 nkat/mg, and a molecular weight of 4 5.40 kDa (SDS-PAGE), In addition to AVLB synthase activity, the purifi ed enzyme shows peroxidase activity, and the VIS spectrum of the prote in presents maxima at 404, 501 and 633 nm, indicating that it is a hig h spin ferric heme protein, belonging to the plant peroxidase superfam ily, Kinetic studies revealed that both catharanthine and vindoline we re substrates of the enzyme, AVLB being the major coupling product. (C ) 1998 Federation of European Biochemical Societies.