Component of iboga and aspidosperma monoterpenoid indole alkaloids (MIAs, e.g. tabersonine and catharanthine) biosynthesis pathway from 19E-geissoschizine. Catalyzes the conversion of O-acetylstemmadenine (OAS) to tabersonine, a precursor of vindoline. dihydroprecondylocarpine acetate = (-)-tabersonine + acetate + H(+) Alkaloid biosynthesis. Interacts with dehydroprecondylocarpine acetate synthase (DPAS). Expressed in leaf epidermis. Reduced accumulation of vindoline and tabersonine, increased biosynthesis of catharanthine, but normal levels of ajmalicine. Belongs to the 'GDXG' lipolytic enzyme family.