ID   4.4.1.1
DE   Cystathionine gamma-lyase.
AN   Cystathionase.
AN   Cystathioninase.
AN   Cysteine desulfhydrase.
AN   Cystine desulfhydrase.
AN   Gamma-cystathionase.
AN   Homoserine deaminase.
AN   Homoserine dehydratase.
CA   L-cystathionine + H(2)O = L-cysteine + NH(3) + 2-oxobutanoate.
CF   Pyridoxal 5'-phosphate.
CC   -!- The enzyme cleaves a carbon-sulfur bond, releasing L-cysteine and an
CC       unstable enamine product that tautomerizes to an imine form, which
CC       undergoes a hydrolytic deamination to form 2-oxobutanoate and
CC       ammonia.
CC   -!- The latter reaction, which can occur spontaneously, can also be
CC       catalyzed by EC 3.5.99.10.
CC   -!- Also catalyzes the conversion of L-homoserine to 2-oxobutanoate and
CC       ammonia, of L-cystine to thiocysteine, pyruvate and ammonia, and of
CC       L-cysteine to pyruvate, hydrogen sulfide and ammonia.
CC   -!- Formerly EC 4.2.1.15.
PR   PROSITE; PDOC00677;
DR   P55216, CGL2_CAEEL ;  F4K5T2, CGL_ARATH  ;  Q58DW2, CGL_BOVIN  ;
DR   Q55DV9, CGL_DICDI  ;  P32929, CGL_HUMAN  ;  Q60HG7, CGL_MACFA  ;
DR   Q8VCN5, CGL_MOUSE  ;  Q19QT7, CGL_PIG    ;  P18757, CGL_RAT    ;
DR   P31373, CYS3_YEAST ;  Q59829, CYSA_STRCO ;  O05394, MCCB_BACSU ;
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