4,4' Diapophytoene synthase

4,4'-diapophytoene synthase (EC 2.5.1.96, dehydrosqualene synthase, DAP synthase, C30 carotene synthase, CrtM) is an enzyme with systematic name farnesyl-diphosphate:farnesyl-diphosphate farnesyltransferase (4,4'-diapophytoene forming). This enzyme catalyses the following chemical reaction

2 (2E,6E)-farnesyl diphosphate ⇌ 4,4'-diapophytoene + 2 diphosphate (overall reaction) (1a) 2 (2E,6E)-farnesyl diphosphate ⇌ diphosphate + presqualene diphosphate (1b) presqualene diphosphate ⇌ 4,4'-diapophytoene + diphosphate

This enzyme requires Mn²⁺. It is present in Staphylococcus aureus and some other bacteria such as Heliobacillus sp.