Phytoene synthase

Phytoene synthase (, prephytoene-diphosphate synthase, 15-cis-phytoene synthase, PSase, geranylgeranyl-diphosphate geranylgeranyltransferase) is a transferase enzyme involved in the biosynthesis of carotenoids. It catalyzes the conversion of geranylgeranyl pyrophosphate to phytoene. This enzyme catalyses the following chemical reaction


 * 2 geranylgeranyl diphosphate $$\rightleftharpoons$$ 15-cis-phytoene + 2 diphosphate (overall reaction)
 * (1a) 2 geranylgeranyl diphosphate $$\rightleftharpoons$$ diphosphate + prephytoene diphosphate
 * (1b) prephytoene diphosphate $$\rightleftharpoons$$ 15-cis-phytoene + diphosphate

This enzyme requires Mn2+ for activity. It belongs to squalene/phytoene synthase family of proteins.