EC	6.2.2.1
Accepted name:	thioglycine synthase
Reaction:	ATP + sulfide + a [methyl-coenzyme M reductase]-glycine = ADP + phosphate + a [methyl-coenzyme M reductase]-thioglycine
Glossary:	thioglycine = 2-aminoethanethioic O-acid
Other name(s):	ycaO (gene name) (ambiguous)
Systematic name:	[methyl-coenzyme M reductase]-glycine—sulfur ligase (thioglycine-forming)
Comments:	Requires Mg2+. The enzyme is found in anaerobic methanogenic and methanotrophic archaea, where it modifies a glycine residue in EC 2.8.4.1, coenzyme-B sulfoethylthiotransferase (methyl-CoM reductase). Upon binding to its substrate, an external source of sulfide attacks the target amide bond generating a tetrahedral intermediate. The amide oxyanion attacks the γ-phosphate of ATP, releasing ADP and forming a phosphorylated thiolate intermediate that collapses to form thioglycine and phosphate. In most organisms activity requires a second protein (TfuA) , which may allosterically activate this enzyme or assist in the delivery of sulfide to the substrate.
References:	1.  Nayak, D.D., Mahanta, N., Mitchell, D.A. and Metcalf, W.W. Post-translational thioamidation of methyl-coenzyme M reductase, a key enzyme in methanogenic and methanotrophic Archaea. Elife 6:e29218 (2017). [PMID: 28880150] 2.  Mahanta, N., Liu, A., Dong, S., Nair, S.K. and Mitchell, D.A. Enzymatic reconstitution of ribosomal peptide backbone thioamidation. Proc. Natl. Acad. Sci. USA 115 (2018) 3030–3035. [PMID: 29507203] 3.  Dong, S.H., Liu, A., Mahanta, N., Mitchell, D.A. and Nair, S.K. Mechanistic basis for ribosomal peptide backbone modifications. ACS Cent. Sci. 5 (2019) 842–851. [PMID: 31139720]
[EC 6.2.2.1 created 2020]