This bacterial enzyme contains an iron(2+) atom coordinated by three protein-derived histidines and a Ser-His-Tyr motif. It is similar to EC 1.13.11.20, cysteine dioxygenase, and can act on L-cysteine, but has a much higher activity with its native substrate, 3-sulfanylpropanoate.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
SYSTEMATIC NAME
IUBMB Comments
3-sulfanylpropanoate:oxygen oxidoreductase
This bacterial enzyme contains an iron(2+) atom coordinated by three protein-derived histidines and a Ser-His-Tyr motif. It is similar to EC 1.13.11.20, cysteine dioxygenase, and can act on L-cysteine, but has a much higher activity with its native substrate, 3-sulfanylpropanoate.
recombinant 3MDO is able to oxidize both cysteine and 3-mercaptopropionic acid in vitro, with a marked preference for 3-mercaptopropionic acid. Substrate binding to the ferrous iron is through the thiol but each substrate may adopt different coordination geometries
recombinant 3MDO is able to oxidize both cysteine and 3-mercaptopropionic acid in vitro, with a marked preference for 3-mercaptopropionic acid. Substrate binding to the ferrous iron is through the thiol but each substrate may adopt different coordination geometries
recombinant 3MDO is able to oxidize both cysteine and 3-mercaptopropionic acid in vitro, with a marked preference for 3-mercaptopropionic acid. Substrate binding to the ferrous iron is through the thiol but each substrate may adopt different coordination geometries
iron content is 0.8 mol of iron per mol of MDO. Addition of NO to 3-mercaptopropanoate-bound enzyme quantitatively yields an iron-nitrosyl species with EPR features consistent with a mononuclear (FeNO)7 site
the monoprotonated ES complexes with 3-mercaptopropionic acid and cysteine have different pKs. At higher pH, kcat decreases sigmoidally with a similar pK regardless of substrate. Loss of reactivity at high pH is attributed to deprotonation of tyrosine 159 and its influence on dioxygen binding
the monoprotonated ES complexes with 3-mercaptopropionic acid and cysteine have different pKs. At higher pH, kcat decreases sigmoidally with a similar pK regardless of substrate. Loss of reactivity at high pH is attributed to deprotonation of tyrosine 159 and its influence on dioxygen binding
active-site cluster models and comparison of CDO, EC 1.13.11.20, and 3-mercaptopropionate dioxygenase MDO. The enzymes have different iron(III)-superoxo-bound structures due to differences in ligand coordination. The differences in the second-coordination sphere and particularly the position of a positively charged Arg residue result in changes in substrate positioning, mobility and enzymatic turnover. For both enzymes, the second oxygen atom transfer has the highest barriers with magnitudes of 14.2 and 15.8 kcal/mol, respectively. Both enzymes have an open-shell singlet-spin iron(III)-superoxo reactant with the substrate bound as a bidentate ligand in the equatorial plane, in MDO the quintet spin state is within 1 kcal/mol. MDO binds the substrate through two anionic bonds of the substrate carboxylate and thiolate groups, and a strong hydrogen-bonding interaction of a Tyr residue towards the superoxo group in MDO is found
active-site cluster models and comparison of CDO, EC 1.13.11.20, and 3-mercaptopropionate dioxygenase MDO. The enzymes have different iron(III)-superoxo-bound structures due to differences in ligand coordination. The differences in the second-coordination sphere and particularly the position of a positively charged Arg residue result in changes in substrate positioning, mobility and enzymatic turnover. For both enzymes, the second oxygen atom transfer has the highest barriers with magnitudes of 14.2 and 15.8 kcal/mol, respectively. Both enzymes have an open-shell singlet-spin iron(III)-superoxo reactant with the substrate bound as a bidentate ligand in the equatorial plane, in MDO the quintet spin state is within 1 kcal/mol. MDO binds the substrate through two anionic bonds of the substrate carboxylate and thiolate groups, and a strong hydrogen-bonding interaction of a Tyr residue towards the superoxo group in MDO is found
a network of hydrogen bonds connects residues H157-Y159 and Fe-bound ligands within the enzymatic Fe site. The hydroxyl group of Y159 hydrogen bonds to Fe-bound NO and, by extension, Fe-bound oxygen during native catalysis. This interaction alters both the NO binding affinity and rhombicity of the 3-mercaptopropanoate-bound iron-nitrosyl site
the monoprotonated ES complexes with 3-mercaptopropionic acid and cysteine have different pKs. At higher pH, kcat decreases sigmoidally with a similar pK regardless of substrate. Loss of reactivity at high pH is attributed to deprotonation of tyrosine 159 and its influence on dioxygen binding. A mechanism model shows deprotonation of tyrosine 159 both blocks oxygen binding and concomitantly promotes cystine formation
the pL-dependent activity of MDO can be rationalized assuming a diprotic enzyme model in which three ionic forms of the enzyme are present [cationic, E(z+1), neutral, Ez, and anionic, E(z-1)]. The activities observed for substrates 3-mercaptopropanoate and cysteine appear to be dominated by electrostatic interactions within the enzymatic active site
the monoprotonated ES complexes with 3-mercaptopropionic acid and cysteine have different pKs. At higher pH, kcat decreases sigmoidally with a similar pK regardless of substrate. Loss of reactivity at high pH is attributed to deprotonation of tyrosine 159 and its influence on dioxygen binding. A mechanism model shows deprotonation of tyrosine 159 both blocks oxygen binding and concomitantly promotes cystine formation
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
comparison with mammalian cysteine dioxygenase. The overall active site geometry is conserved but the different substrate specificity may be related to replacement of an arginine by a glutamine in the active site
variant is able to form a cysteine-tyrosine crosslink homologous to that found in mammalian cysteine dioxygenases. Activity of this variant is severely impaired
variant is able to form a cysteine-tyrosine crosslink homologous to that found in mammalian cysteine dioxygenases. Activity of this variant is severely impaired
Outer-sphere tyrosine 159 within the 3-mercaptopropionic acid dioxygenase S-H-Y motif gates substrate-coordination denticity at the non-heme iron active site
3-Mercaptopropionate dioxygenase, a cysteine dioxygenase homologue, catalyzes the initial step of 3-mercaptopropionate catabolism in the 3,3-thiodipropionic acid-degrading bacterium variovorax paradoxus