. "The enzyme appears to be stereospecific, normally producing 15-cis-phytoene." . "However, in Erwinia herbicola, the product is the 15-trans isomer." . . . "Phytoene synthase" . "Geranylgeranyl-diphosphate geranylgeranyltransferase" . "Prephytoene-diphosphate synthase" . "Phytoene synthetase" . "PSase" . "2 geranylgeranyl diphosphate = phytoene + 2 diphosphate." . "Manganese" .