Oryzalide A is a diterpenoid phytoalexin synthesized in response to pathogen attack. The enzyme ent-isokaurene synthase is very stereospecific and a single amino acid change in active site of enzyme leads to production of different product from same substrate. The last reaction is catalyzed by ent-isokaurene-C2-hydroxylase to produce ent-2?-hydroxyisokaurene which further converts into oryzalide A.
