EC 4.4.1.28 - L-cysteine desulfidase
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IntEnz Enzyme Nomenclature
EC 4.4.1.28
Names
Accepted name:
L-cysteine desulfidase
Other
name:
L-cysteine desulfhydrase
Systematic name:
L-cysteine sulfide-lyase (deaminating; pyruvate-forming)
Reactions
- (1) L-cysteine + H2O = sulfide + NH3 + pyruvate
- (2) (1a) L-cysteine = 2-aminoprop-2-enoate + sulfide
- (3) (1b) 2-aminoprop-2-enoate = 2-iminopropanoate (spontaneous)
- (4) (1c) 2-iminopropanoate + H2O = pyruvate + NH3 (spontaneous)
Comments:
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).
Links to other databases
References
-
L-cysteine desulfidase: an [4Fe-4S] enzyme isolated from Methanocaldococcus jannaschii that catalyzes the breakdown of L-cysteine into pyruvate, ammonia, and sulfide.Biochemistry 44 : 1659-1670 (2005). [PMID: 15683250]
[EC 4.4.1.28 created 2014]