Oxidation of rotenone by Polyporus anceps laccase.

The extracellular laccase produced by Polyporus anceps transforms rotenone to a single, more polar product. This transformation occurs in incubation mixtures containing chlorpromazine, laccase, and rotenone where rotenone serves as a pseudosubstrate for the enzyme. Chlorpromazine, the true substrate, serves as a cycling redox component of the system forming a radical-cation species that abstracts an electron from rotenone in the oxidation process. Physicochemical properties of the product were determined on an analytically pure sample obtained by preparative hplc. High resolution ms, high-field pmr and cmr, uv, and optical rotation analyses indicated that rotenone had been transformed to 6a beta, 12a beta-rotenolone by P. anceps laccase.