Chemoproteomic profiling provides a complementary approach for linking natural products to their corresponding enzymes. A previously unrecognized polyphenol oxidase, SmPPOA, was identified from Salvia miltiorrhiza using a 3D carbene-immobilized salvianolic acid B. SmPPOA catalyzes oxidative lactonization of salvianolic acid B to generate salvianolic acid O via a cascade of oxidation and intramolecular Michael addition using the carboxylate anion as the Michael donor. This strategy can facilitate discovery of biosynthetic enzymes for plant natural products.
Xu et al. (Fri,) studied this question.