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ENZYME entry: EC 4.4.1.1

Accepted Name
Cystathionine gamma-lyase.
Alternative Name(s)
Cystathionase.
Cystathioninase.
Cysteine desulfhydrase.
Cystine desulfhydrase.
Gamma-cystathionase.
Homoserine deaminase.
Homoserine dehydratase.
Reaction catalysed
L-cystathionine + H(2)O <=> L-cysteine + NH(3) + 2-oxobutanoate
Cofactor(s)
Pyridoxal 5'-phosphate.
Comment(s)
  • The enzyme cleaves a carbon-sulfur bond, releasing L-cysteine and an unstable enamine product that tautomerizes to an imine form, which undergoes a hydrolytic deamination to form 2-oxobutanoate and ammonia.
  • The latter reaction, which can occur spontaneously, can also be catalyzed by EC 3.5.99.10.
  • Also catalyzes the conversion of L-homoserine to 2-oxobutanoate and ammonia, of L-cystine to thiocysteine, pyruvate and ammonia, and of L-cysteine to pyruvate, hydrogen sulfide and ammonia.
  • Formerly EC 4.2.1.15.
Cross-references
PROSITEPDOC00677
BRENDA4.4.1.1
EC2PDB4.4.1.1
ExplorEnz4.4.1.1
PRIAM enzyme-specific profiles4.4.1.1
KEGG Ligand Database for Enzyme Nomenclature4.4.1.1
IUBMB Enzyme Nomenclature4.4.1.1
IntEnz4.4.1.1
MEDLINEFind literature relating to 4.4.1.1
MetaCyc4.4.1.1
Rhea expert-curated reactions4.4.1.1
UniProtKB/Swiss-Prot
P55216, CGL2_CAEEL;  F4K5T2, CGL_ARATH;  Q58DW2, CGL_BOVIN;  
Q55DV9, CGL_DICDI;  P32929, CGL_HUMAN;  Q60HG7, CGL_MACFA;  
Q8VCN5, CGL_MOUSE;  Q19QT7, CGL_PIG;  P18757, CGL_RAT;  
P31373, CYS3_YEAST;  Q59829, CYSA_STRCO;  O05394, MCCB_BACSU;  

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