Homocysteine desulfhydrase

The enzyme homocysteine desulfhydrase (EC 4.4.1.2) catalyzes the chemical reaction

homocysteine desulfhydrase
Identifiers
EC no.4.4.1.2
CAS no.9024-41-3
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L-homocysteine + H2O = hydrogen sulfide + NH3 + 2-oxobutanoate (overall reaction)
(1a) L-homocysteine = hydrogen sulfide + 2-aminobut-2-enoate
(1b) 2-aminobut-2-enoate = 2-iminobutanoate (spontaneous)
(1c) 2-iminobutanoate + H2O = 2-oxobutanoate + NH3 (spontaneous)

This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is L-homocysteine hydrogen-sulfide-lyase (deaminating; 2-oxobutanoate-forming). Other names in common use include homocysteine desulfurase, L-homocysteine hydrogen-sulfide-lyase (deaminating). This enzyme participates in nitrogen and sulfur metabolism. It employs one cofactor, pyridoxal phosphate.

References

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  • Kallio RE (September 1951). "Function of pyridoxal phosphate in desulfhydrase systems of Proteus morganii". The Journal of Biological Chemistry. 192 (1): 371–7. doi:10.1016/S0021-9258(18)55941-X. PMID 14917685.