Cannabidiolic-acid synthase, the chemotype-determining enzyme in the fiber-type Cannabis sativa.

Cannabidiolic-acid (CBDA) synthase is the enzyme that catalyzes oxidative cyclization of cannabigerolic-acid into CBDA, the dominant cannabinoid constituent of the fiber-type Cannabis sativa. We cloned a novel cDNA encoding CBDA synthase by reverse transcription and polymerase chain reactions with degenerate and gene-specific primers. Biochemical characterization of the recombinant enzyme demonstrated that CBDA synthase is a covalently flavinylated oxidase. The structural and functional properties of CBDA synthase are quite similar to those of tetrahydrocannabinolic-acid (THCA) synthase, which is responsible for the biosynthesis of THCA, the major cannabinoid in drug-type Cannabis plants.