Reaction: dehydrosecondine + acetate + NADP+ = precondylocarpine acetate + NADPH + H+ (overall reaction)
(1a) dihydroprecondylocarpine acetate + NADP+ = precondylocarpine acetate + NADPH + H+
(1b) dihydroprecondylocarpine acetate (enamine form) = dihydroprecondylocarpine acetate (spontaneous)
(1c) dehydrosecondine + acetate = dihydroprecondylocarpine acetate (enamine form) (spontaneous)
For diagram of reaction, click here and part mechanism click here
Other name(s): DPAS (gene name); dihydroprecondylocarpine acetate synthase
Systematic name: precondylocarpine acetate:NADP+ oxidoreductase
Comments: The enzyme, characterized from the plant Catharanthus roseus (Madagascar periwinkle), participates in a pathway that leads to the production of a number of monoterpene alkaloids, as well as the bisindole alkaloids vinblastine and vincristine, which are used as anticancer drugs. The enzyme forms the iminium ion form of dihydroprecondylocarpine acetate, which spontaneously rearranges and undergoes deacylation, producing dehydrosecodine.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Caputi, L., Franke, J., Farrow, S.C., Chung, K., Payne, R.ME., Nguyen, T.D., Dang, T.T., Soares Teto Carqueijeiro, I., Koudounas, K., Duge de Bernonville, T., Ameyaw, B., Jones, D.M., Vieira, I.JC., Courdavault, V. and O'Connor, S.E. Missing enzymes in the biosynthesis of the anticancer drug vinblastine in Madagascar periwinkle. Science 360 (2018) 1235-1239. [PMID: 29724909]
2. Caputi, L., Franke, J., Bussey, K., Farrow, S.C., Vieira, I.JC., Stevenson, C.EM., Lawson, D.M. and O'Connor, S.E. Structural basis of cycloaddition in biosynthesis of iboga and aspidosperma alkaloids. Nat. Chem. Biol. 16 (2020) 383–386. [PMID: 32066966]
3. DeMars, M.D., 2nd and O'Connor, S.E. Evolution and diversification of carboxylesterase-like [4+2] cyclases in aspidosperma and iboga alkaloid biosynthesis. Proc. Natl. Acad. Sci. USA 121 (2024) e2318586121. [PMID: 38319969]