Properties of Kaurene Synthetase from Marah macrocarpus Endosperm: Evidence for the Participation of Separate but Interacting Enzymes

Ent-kaurene is synthesized from geranylgeranyl pyrophosphate in a two step sequence catalyzed by kaurene synthetase; the first step (A activity) involves the conversion of geranylgeranyl pyrophosphate into the intermediate ent-trans labda-8(17), 13-dien-15-yl pyrophosphate (copalyl pyrophosphate) which is further cyclized to ent-kaurene in the second step (B activity). The resolution of enzyme fractions which catalyze each step independent of the other has been accomplished for the first time by means of QAE Sephadex A-50 chromatography and polyacrylamide gel electrophoresis of kaurene synthetase preparations from endosperm tissue of immature seed of Marah macrocarpus. Molecular weights for the A and B enzymes were each estimated as approximately 82,000 by means of gel filtration chromatography and sedimentation velocity determinations.