Cystathionine gamma-synthase

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cystathionine gamma-synthase
Cystathionine gamma-synthase homotetramer, Helicobacter pylori
EC no.
CAS no.9030-70-0
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO

In enzymology, a cystathionine gamma-synthase (EC is an enzyme that catalyzes the formation of cystathionine from cysteine and an activated derivative of homoserine, e.g.:

O4-succinyl-L-homoserine + L-cysteine L-cystathionine + succinate
Cystathionine gamma-synthase.svg

In microorganisms, the activated substrate of this enzyme is O4-succinyl-L-homoserine or O4-acetyl-L-homoserine. Cystathionine gamma-synthase from plants uses L-homoserine phosphate instead.[1]

This enzyme belongs to the family of transferases, specifically those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is O4-succinyl-L-homoserine:L-cysteine S-(3-amino-3-carboxypropyl)transferase. Other names in common use include O-succinyl-L-homoserine succinate-lyase (adding cysteine), O-succinylhomoserine (thiol)-lyase, homoserine O-transsuccinylase, O-succinylhomoserine synthase, O-succinylhomoserine synthetase, cystathionine synthase, cystathionine synthetase, homoserine transsuccinylase, 4-O-succinyl-L-homoserine:L-cysteine, and S-(3-amino-3-carboxypropyl)transferase. This enzyme participates in 4 metabolic pathways: methionine metabolism, cysteine metabolism, selenoamino acid metabolism, and sulfur metabolism. It employs one cofactor, pyridoxal phosphate.


  1. ^ Steegborn C, Laber B, Messerschmidt A, Huber R, Clausen T (August 2001). "Crystal structures of cystathionine gamma-synthase inhibitor complexes rationalize the increased affinity of a novel inhibitor". Journal of Molecular Biology. 311 (4): 789–801. doi:10.1006/jmbi.2001.4880. PMID 11518531.