MetaCyc Enzyme: 4-imidazolone-5-propionate oxidase

Species: Cavia porcellus

The enzyme catalyzing the oxidation of 4-imidazolone-5-propanoate to hydantoin-5-propanoate has been partially purified from Cavia porcellus (guinea pig). The enzyme contained FAD, and removal of the FAD cofactor destroyed the enzyme's activity. The addition of FAD to the inactive enzyme did not restore activity. The reaction consumed 0.5 mole of oxygen per mole of product formed [Hassall68].

It was previously shown that this reaction can be be catalyzed by a a xanthine oxidase (EC ) isolated from milk [Hassall63]. However, 4-imidazolone-5-propionate oxidase from Cavia porcellus is clearly a different enzyme, as, unlike a xanthine oxidase, it was not able to oxidize xanthine [Hassall68].

Gene-Reaction Schematic

Gene-Reaction Schematic

Enzymatic reaction of: 4-imidazolone-5-propionate oxidase

Inferred from experiment

EC Number: 1.17.3.-

4-imidazolone-5-propanoate + oxygen + H2O → hydantoin-5-propanoate + hydrogen peroxide

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.

In Pathways: L-histidine degradation VI

Cofactors or Prosthetic Groups: FAD [Hassall68]

Inhibitors (Other): hydrogen cyanide [Hassall68] Inhibitors (Unknown Mechanism): atabrine [Hassall68]Kinetic Parameters:
Substrate Km (μM) Citations
4-imidazolone-5-propanoate 500.0 [Hassall68]

pH(opt): 5.8 [Hassall68]


Hassall63: Hassall, H., Greenberg, D.M. (1963). "The oxidation of 4(5)-imidazolone-5(4)-propionic acid to hydantoin-5-propionic acid by xanthine oxidase." Biochim Biophys Acta 67;507-10. PMID: 13960896

Hassall68: Hassall H, Greenberg DM (1968). "Studies on the enzymic decomposition of urocanic acid. VI. Properties of the enzyme catalyzing the oxidation of 4(5)-imidazolone-5(4)-propionic acid to L-hydantoin-5-propionic acid." Arch Biochem Biophys 125(1);278-85. PMID: 4967723

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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