Phytoene synthase

15-cis-phytoene synthase
Identifiers
EC number	2.5.1.32
CAS number	50936-61-3
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Search PMC articles PubMed articles NCBI proteins

Phytoene synthase (EC 2.5.1.32, 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.^[1][2][3] 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.

References

1. Phytoene synthase
2. Gregonis, D.E. and Rilling, H.C. (1974). "The stereochemistry of trans-phytoene synthesis. Some observations on lycopersene as a carotene precursor and a mechanism for the synthesis of cis- and trans-phytoene". Biochemistry 13 (7): 1538–1542. doi:10.1021/bi00704a033. PMID 4819767.
3. Misawa, N., Truesdale, M.R., Sandmann, G., Fraser, P.D., Bird, C., Schuch, W. and Bramley, P.M. (1994). "Expression of a tomato cDNA coding for phytoene synthase in Escherichia coli, phytoene formation in vivo and in vitro, and functional analysis of the various truncated gene products". J. Biochem. (Tokyo) 116 (5): 980–985. PMID 7896759.