ID 1.3.99.29 DE phytoene desaturase (zeta-carotene-forming). AN 2-step phytoene desaturase. CA 15-cis-phytoene + 2 A = 2 AH2 + all-trans-zeta-carotene. CC -!- The enzyme is involved in carotenoid biosynthesis and catalyzes up to CC two desaturation steps (cf. EC 1.3.99.28, EC 1.3.99.30 and CC EC 1.3.99.31). DR P54979, CRTJ_MYXXA ; //