|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions → Composite Reactions|
|Reactions Classified By Substrate → Small-Molecule Reactions|
EC Number: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
Mass balance status: Balanced.
Enzyme Commission Primary Name: cysteine desulfurase
Enzyme Commission Synonyms: IscS, NIFS, NifS, SufS, cysteine desulfurylase
an [L-cysteine desulfurase]-L-cysteine + L-cysteine → an [L-cysteine desulfurase] L-cysteine persulfide + L-alanine ,
an [L-cysteine desulfurase] L-cysteine persulfide + an unsulfurated [sulfur carrier] ↔ an [L-cysteine desulfurase]-L-cysteine + a sulfurated [sulfur carrier]
Enzyme Commission Summary:
A pyridoxal-phosphate protein. The sulfur from free L-cysteine is first transferred to a cysteine residue in the active site, and then passed on to various other acceptors. The enzyme is involved in the biosynthesis of iron-sulfur clusters, thio-nucleosides in tRNA, thiamine, biotin, lipoate and pyranopterin (molybdopterin) [Mihara02a]. In Azotobacter vinelandii, this sulfur provides the inorganic sulfide required for nitrogenous metallocluster formation [Zheng93].
This is an overall reaction, which is composed of the two reactions listed above.
Zheng93: Zheng L, White RH, Cash VL, Jack RF, Dean DR (1993). "Cysteine desulfurase activity indicates a role for NIFS in metallocluster biosynthesis." Proc Natl Acad Sci U S A 90(7);2754-8. PMID: 8464885
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