A non-heme iron protein that is involved in the biosynthesis of taurine. 3-Aminopropanethiol (homocysteamine) and 2-sulfanylethan-1-ol (2-mercaptoethanol) can also act as substrates, but glutathione, cysteine, and cysteine ethyl- and methyl esters are not good substrates [1,3].
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SYSTEMATIC NAME
IUBMB Comments
2-aminoethanethiol:oxygen oxidoreductase
A non-heme iron protein that is involved in the biosynthesis of taurine. 3-Aminopropanethiol (homocysteamine) and 2-sulfanylethan-1-ol (2-mercaptoethanol) can also act as substrates, but glutathione, cysteine, and cysteine ethyl- and methyl esters are not good substrates [1,3].
substrate cysteamine is capable of reducing the catalytically inactive ferric center to the enzymatically active ferrous state. Presence of cysteamine alters the binding behavior of nitric oxide to the nonheme iron center of ADO
ADO catalyzes conversion of N-terminal cysteine to cysteine sulfinic acid, reaction of EC 1.13.11.20, and is related to the plant cysteine oxidases that mediate responses to hypoxia by an identical post-translational modification. In human cells ADO regulates the RGS4/5 (regulator of G-protein signalling) N-degron substrates, modulates G-protein coupled Ca2+ signals and MAPK activity, and acts on N-terminal cysteine proteins including the angiogenic cytokine IL-32. Inactivation of ADO leads to constitutive upregulation of endogenous and transfected RGS4 and RGS5 proteins irrespective of oxygen levels
functional roles of ADO in metabolism include removal of thiol substrates (cysteamine), thus regulating cysteine or cysteamine levels in body tissues and fluids and production of hypotaurine/taurine from cysteine metabolite cysteamine
in the presence of nitric oxide as a spin probe and oxygen surrogate, both cysteamine and the peptide substrate regulator of G protein signaling 5 coordinate the iron center with their free thiols in a monodentate binding mode. A substrate-bound B-type dinitrosyl iron center complex is observed, as well as a substrate-mediated reduction of the iron center from ferric to the ferrous oxidation state with possible disulfide formation of the substrates
presence of a Cys-Tyr cofactor, crosslinked between Cys220 and Tyr222 through a thioether (C-S) bond. An autocatalytic oxidative carbon-fluorine bond activation and fluoride release is observed. The crosslinking results in a minimal structural change of the protein. A sequence motif C-X-Y-Y(F) is proposed for identifying Cys-Tyr crosslink
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
structure of human ADO at a resolution of 1.78 A with a nickel-bound metal center. Crystallization is achieved through both metal substitution and C18S/C239S double mutations. The metal center resides in a tunnel close to an entry site flanked by loops. ADO appears to use extensive flexibility to handle substrates of different sizes, and also employs proline and proline pairs to maintain the core protein structure and to retain the residues critical for catalysis in place