Cystathionine beta-lyase

cystathionine beta-lyase
Identifiers
EC number	4.4.1.8
CAS number	9055-05-4
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / EGO
Search PMC articles PubMed articles NCBI proteins

In enzymology, a cystathionine beta-lyase (EC 4.4.1.8) is an enzyme that catalyzes the chemical reaction

L-cystathionine + H₂O $\rightleftharpoons$ L-homocysteine + NH₃ + pyruvate

Thus, the two substrates of this enzyme are L-cystathionine and H₂O, whereas its 3 products are L-homocysteine, NH₃, and pyruvate.

This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is L-cystathionine L-homocysteine-lyase (deaminating; pyruvate-forming). Other names in common use include beta-cystathionase, cystine lyase, cystathionine L-homocysteine-lyase (deaminating), and L-cystathionine L-homocysteine-lyase (deaminating). This enzyme participates in 5 metabolic pathways: methionine metabolism, cysteine metabolism, selenoamino acid metabolism, nitrogen metabolism, and sulfur metabolism. It employs one cofactor, pyridoxal phosphate.

Structural studies

As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes 1CL1, 1CL2, 1IBJ, 2FQ6, and 2GQN.

References

• Anderson NW and Thompson JF (1979). "Cystine lyase: beta-cystathionase from turnip roots". Phytochemistry 18 (12): 1953–1958. doi:10.1016/S0031-9422(00)82710-7.
• FLAVIN M, SLAUGHTER C (1964). "CYSTATHIONINE CLEAVAGE ENZYMES OF NEUROSPORA". J. Biol. Chem. 239: 2212–9. PMID 14209950.