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EC 4.4.1.28 Details
show Brenda entryEC number
4.4.1.28
Accepted name
L-cysteine desulfidase
Reaction
L-cysteine + H2O = sulfide + NH3 + pyruvate (overall reaction);; (1a) L-cysteine = 2-aminoprop-2-enoate + sulfide;; (1b) 2-aminoprop-2-enoate = 2-iminopropanoate (spontaneous);; (1c) 2-iminopropanoate + H2O = pyruvate + NH3 (spontaneous)
Other name(s)
L-cysteine desulfhydrase
Systematic name
L-cysteine sulfide-lyase (deaminating; pyruvate-forming)
Comment
The enzyme from the archaeon Methanocaldococcus jannaschii contains a [4Fe-4S] cluster and is specific for L-cysteine (cf. EC 4.4.1.1, cystathionine γ-lyase). It cleaves a carbon-sulfur bond releasing sulfide and the unstable enamine product 2-aminoprop-2-enoate that tautomerizes to an imine form, which undergoes a hydrolytic deamination to form pyruvate and ammonia. The same reaction can also be catalysed by some pyridoxal-phosphate proteins (cf. EC 4.4.1.1, cystathionine γ-lyase).
History
created 2014
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1 Oxidoreductases
1.1 Acting on the CH-OH group of donors
1.14.13.45 created 1992, deleted 2003
