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Literature summary for 1.14.99.50 extracted from

  • Faponle, A.S.; Seebeck, F.P.; de Visser, S.P.
    Sulfoxide synthase versus cysteine dioxygenase reactivity in a nonheme iron enzyme (2017), J. Am. Chem. Soc., 139, 9259-9270 .
    View publication on PubMed

Metals/Ions

Metals/Ions Comment Organism Structure
Fe2+ non-heme iron, requied for catalysis Mycolicibacterium thermoresistibile

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
hercynine + gamma-L-glutamyl-L-cysteine + O2 Mycolicibacterium thermoresistibile
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gamma-L-glutamyl-S-(hercyn-2-yl)-L-cysteine S-oxide + H2O
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?
hercynine + gamma-L-glutamyl-L-cysteine + O2 Mycolicibacterium thermoresistibile ATCC 19527
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gamma-L-glutamyl-S-(hercyn-2-yl)-L-cysteine S-oxide + H2O
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?

Organism

Organism UniProt Comment Textmining
Mycolicibacterium thermoresistibile G7CFI3
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Mycolicibacterium thermoresistibile ATCC 19527 G7CFI3
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Reaction

Reaction Comment Organism Reaction ID
hercynine + gamma-L-glutamyl-L-cysteine + O2 = gamma-L-glutamyl-S-(hercyn-2-yl)-L-cysteine S-oxide + H2O EgtB contains a conserved tyrosine residue that reacts via proton-coupled electron transfer with the iron(III)-superoxo species and creates an iron(III)-hydroperoxo intermediate, thereby preventing the possible thiolate dioxygenation side reaction. The nucleophilic C-S bond-formation step happens subsequently concomitant to relay of the proton of the iron(II)-hydroperoxo back to Tyr377. This is the rate-determining step in the reaction cycle and is followed by hydrogen-atom transfer from the CE1-H group of trimethyl histidine substrate to iron(II)-superoxo. In the final step, a quick and almost barrierless sulfoxidation leads to the sulfoxide product complexes. Quantum mechanics/molecular mechanics study of the mechanism of sulfoxide synthase enzymes as compared to cysteine dioxygenase enzymes and present pathways for both reaction channels in EgtB, reaction mechanism, overview. The active site contains the unusual Tyr157-Cys93 cross-link with a covalent bond between the two amino acid residues. It is believed this cross-link has a steric effect on the overall reaction mechanism. The fast CDO-type side reaction is prevented through a proton-coupled electron transfer from Tyr377 to iron(III)-superoxo, which enables the slower C-S bond formation to take place and blocks the sulfur dioxygenation side reaction Mycolicibacterium thermoresistibile

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
hercynine + gamma-L-glutamyl-L-cysteine + O2
-
Mycolicibacterium thermoresistibile gamma-L-glutamyl-S-(hercyn-2-yl)-L-cysteine S-oxide + H2O
-
?
hercynine + gamma-L-glutamyl-L-cysteine + O2
-
Mycolicibacterium thermoresistibile ATCC 19527 gamma-L-glutamyl-S-(hercyn-2-yl)-L-cysteine S-oxide + H2O
-
?

Synonyms

Synonyms Comment Organism
EgtB
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Mycolicibacterium thermoresistibile
sulfoxide synthase
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Mycolicibacterium thermoresistibile

General Information

General Information Comment Organism
metabolism the enzyme catalyzes the key step in the biosynthesis of ergothioneine Mycolicibacterium thermoresistibile
additional information density functional theory modeling of active-site models of EgtB in a polarized continuum model propose a reaction mechanism starting with sulfoxidation (OAT) of gammaGC followed by C-S bond formation and deprotonation (PT) to form products. Optimized QM geometry of the S-O bond formation transition state for the reaction of iron(III)-superoxo with cysteine in EgtB, overview Mycolicibacterium thermoresistibile
physiological function sulfoxide synthase EgtB represents is a non-heme iron enzyme that catalyzes the formation of a C-S bond between N-alpha-trimethyl histidine and gamma-glutamyl cysteine, which is the key step in the biosynthesis of ergothioneine, an important amino acid related to aging Mycolicibacterium thermoresistibile