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Literature summary for 1.17.1.4 extracted from

  • Reschke, S.; Mebs, S.; Sigfridsson-Clauss, K.G.; Kositzki, R.; Leimkuehler, S.; Haumann, M.
    Protonation and sulfido versus oxo ligation changes at the molybdenum cofactor in xanthine dehydrogenase (XDH) variants studied by X-ray absorption spectroscopy (2017), Inorg. Chem., 56, 2165-2176 .
    View publication on PubMed

Protein Variants

Protein Variants Comment Organism
E730A crystal structure determination and analysis, comparison with wild-type enzyme structure, the sulfido is replaced with an oxo ligand in the inactive E730A mutant, further showing another oxo and one Mo-OH ligand at Mo, which are independent of pH Rhodobacter capsulatus
additional information the enzyme mutants show alterations in the Mo site structure, which changes in a pH range of 5-10, and in the influence of amino acids (Glu730 and Gln179) close to molybdenum cofactor in wild-type, and Q179A and E730A mutants, enzyme kinetics and quantum chemical studies, overview Rhodobacter capsulatus
Q179A crystal structure determination and analysis, comparison with wild-type enzyme structure, a similar acidic pK for the wild-type and Q179A variants, as well as the metrical parameters of the Mo site and density functional theory calculations, suggested protonation at the equatorial oxo group. Oxidized wild-type and mutant Q179A reveal a similar Mo(VI) ion with each one molybdopterin, Mo=O, Mo-O-, and Mo=S ligand, and a weak Mo-O(E730) bond at alkaline pH Rhodobacter capsulatus

Metals/Ions

Metals/Ions Comment Organism Structure
Molybdenum in the molybdenum cofactor, the metal ion binds a molybdopterin (MPT) molecule via its dithiolene function and terminal sulfur and oxygen groups. Oxidized wild-type and mutant Q179A reveal a similar Mo(VI) ion with each one molybdopterin, Mo=O, Mo-O-, and Mo=S ligand, and a weak Mo-O(E730) bond at alkaline pH Rhodobacter capsulatus

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
xanthine + NAD+ + H2O Rhodobacter capsulatus
-
urate + NADH + H+
-
?

Organism

Organism UniProt Comment Textmining
Rhodobacter capsulatus
-
-
-

Reaction

Reaction Comment Organism Reaction ID
xanthine + NAD+ + H2O = urate + NADH + H+ a reaction mechanism for XDH is suggested in which an initial oxo rather than a hydroxo group and the sulfido ligand are essential for xanthine oxidation Rhodobacter capsulatus

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
xanthine + NAD+ + H2O
-
Rhodobacter capsulatus urate + NADH + H+
-
?

Synonyms

Synonyms Comment Organism
XDH
-
Rhodobacter capsulatus

Cofactor

Cofactor Comment Organism Structure
molybdenum cofactor MoCo, the metal ion binds a molybdopterin (MPT) molecule via its dithiolene function and terminal sulfur and oxygen groups Rhodobacter capsulatus
[2Fe-2S]-center
-
Rhodobacter capsulatus

General Information

General Information Comment Organism
evolution the enzyme belongs to the xanthine oxidase family Rhodobacter capsulatus
additional information analysis of the mechanism of transfer of an oxygen atom to the substrate Rhodobacter capsulatus