| Zeta-carotene desaturase, chloroplastic/chromoplastic | Catalyzes the conversion of zeta-carotene to lycopene via the intermediary of neurosporene. It carries out two consecutive desaturations (introduction of double bonds) at positions C-7 and C-7'. Shows stereoselectivity toward trans C15-C15'zeta-carotene double bond. The zeta-carotene produced by the phytoene desaturase PDS has a C15-C15' double bond in the cis configuration and it requires isomerization before being recognized as substrate by ZDS. The main product is 7,9,7',9'-tetra-cis-lycopene (pro-lycopene). | probable | Q38893 | 