MetaCyc Enzyme: β-keto-L-gulonic acid decarboxylase

Species: Cavia porcellus

This enzyme remains poorly characterized (reviewed in [Linster07]. Decarboxylation of 3-keto-L-gulonate (β-keto-L-gulonate) has been demonstrated in a hog kidney homogenate and in the high speed supernatant fraction from rat liver [Smiley61]. It was partially purified from guinea pig ( Cavia porcellus) liver [WINKELMAN61]. A 2,3-diketo-L-gulonate decarboxylase was purified from rat liver and was suggested to possibly be the same enzyme [Kagawa70].

Gene-Reaction Schematic

Gene-Reaction Schematic

Created 26-Jun-2007 by Fulcher CA, SRI International

Enzymatic reaction of: β-keto-L-gulonic acid decarboxylase

Inferred from experiment

Synonyms: dehydro-L-gulonate decarboxylase

EC Number:

3-keto-L-gulonate + H+ → L-xylulose + CO2

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

Alternative Substrates for 3-keto-L-gulonate: 2,3-dioxo-L-gulonate [WINKELMAN61]

In Pathways: D-glucuronate degradation I

β-Keto-L-gulonic acid decarboxylase showed pH optima at 5.2 and 7.6. Assays were performed at pH 7.6. No cofactors were required. Acetoacetate and oxaloacetate were not substrates for the enzyme. Xylulose was identified as the reaction product [WINKELMAN61].

Inhibitors (Unknown Mechanism): diethyldithiocarbamate [WINKELMAN61], Cu2+ [WINKELMAN61], Fe2+ [WINKELMAN61], Cd2+ [WINKELMAN61], p-chloromercuribenzoate [WINKELMAN61]


Kagawa70: Kagawa Y, Shimazono N (1970). "Catabolism of L-ascorbate in animal tissues." Methods Enzymol. 18:46-50.

Linster07: Linster CL, Van Schaftingen E (2007). "Vitamin C. Biosynthesis, recycling and degradation in mammals." FEBS J 274(1);1-22. PMID: 17222174

Smiley61: Smiley DJ, Ashwell G (1961). "Purification and Properties of β-L-hydroxy Acid Dehydrogenase II. Isolation of β-keto-L-gulonic acid, and intermediate in L-xylulose biosynthesis." J. Biol. Chem. 236 (2) 357-364.

WINKELMAN61: WINKELMAN J, ASHWELL G (1961). "Enzymic formation of L-xylulose from beeta-keto-L-gulonic acid." Biochim Biophys Acta 52;170-5. PMID: 14007506

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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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