Substrate Specificity of Vinorine Hydroxylase, a Novel Membrane-bound Key Enzyme of Rauwolfia Indole Alkaloid Biosynthesis

Dual Catalytic Activity of a Cytochrome P450 Controls Bifurcation at a Metabolic Branch Point of Alkaloid Biosynthesis in Rauwolfia serpentina

“…Vomilenine, the hydroxylated product of vinorine, was the only other alkaloid accepted by 5437, albeit with much lower efficiency (13 % of the substrate turnover rate compared with vinorine; Figure B). This high substrate specificity is consistent with previous work with microsomal extracts of Rauwolfia . The closest homologue of 5437 in the related Apocynaceae plant Catharanthus roseus (cra_locus_12789) did not accept vinorine as a substrate.…”

“…All biosynthetic transformations leading from strictosidine to ajmaline have been detected in enzyme fractions from Rauwolfia cell culture, though only six biosynthetic genes have been cloned and characterized (Figure ) . Several studies showed that vomilenine is an ajmaline biosynthetic intermediate that is produced through selective hydroxylation of vinorine at the C‐21 position by Rauwolfia cell culture extracts (Figure ) . However, no enzyme isolated from R. serpentina has shown this activity …”