Homocysteine desulfhydrase

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In enzymology, a homocysteine desulfhydrase (EC is an enzyme that catalyzes the chemical reaction

L-homocysteine + H2O hydrogen sulfide + NH3 + 2-oxobutanoate

Thus, the two substrates of this enzyme are L-homocysteine and H2O, whereas its 3 products are hydrogen sulfide, NH3, and 2-oxobutanoate.

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, and (deaminating). This enzyme participates in nitrogen metabolism and sulfur metabolism. It employs one cofactor, pyridoxal phosphate.


  • IUBMB entry for
  • BRENDA references for (Recommended.)
  • PubMed references for
  • PubMed Central references for
  • Google Scholar references for
  • KALLIO RE (1951). "Function of pyridoxal phosphate in desulfhydrase systems of Proteus morganii". J. Biol. Chem. 192: 371&ndash, 7. PMID 14917685.

External links

The CAS registry number for this enzyme class is 9024-41-3.

Gene Ontology (GO) codes