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Metabolic Modeling Tutorial
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Escherichia coli K-12 substr. MG1655 Enzyme: D-galactono-γ-lactonase / gluconolactonase

Summary:
No gene encoding an enzyme with this enzymatic activity has been identified to date.

Gene-Reaction Schematic: ?

Credits:
Curated 17-Mar-2010 by Fulcher C , SRI International
Last-Curated ? 11-Jun-2012 by Mackie A , Macquarie University


Enzymatic reaction of: D-galactono-γ-lactonase

EC Number: 3.1.1.25

D-galactono-1,4-lactone + H2O <=> D-galactonate + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

Summary:
A gluconolactonase activity was partially purified from Escherichia coli K-12 and was shown to hydrolyze glucono-δ-lactone in an assay based on the spectral change of a nitrophenol pH indicator, resulting from lactone hydrolysis to an acid. Among other substrates tested, only D-galactono-γ-lactone was hydrolyzed in significant amounts by this enzyme [Hucho72]. D-galactonate produced in this reaction could enter the pathway of D-galactonate degradation.

L-galactono-γ-lactone was not tested. It is not clear if this activity resides in the periplasm or the cytoplasm of E.coli.


Enzymatic reaction of: gluconolactonase

Synonyms: lactonase, aldonolactonase, glucono-δ-lactonase, D-glucono-1,5-lactone lactonohydrolase

EC Number: 3.1.1.17

D-glucono-1,5-lactone + H2O <=> D-gluconate + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

The reaction is physiologically favored in the direction shown.

In Pathways: glucose and glucose-1-phosphate degradation

Summary:
A gluconolactonase activity was partially purified from Escherichia coli K-12 and was shown to hydrolyze glucono-δ-lactone in an assay based on the spectral change of a nitrophenol pH indicator, resulting from lactone hydrolysis to an acid. Among other substrates tested, only galactono-γ-lactone was hydrolyzed in significant amounts by this enzyme [Hucho72].

The fate of the D-gluconate produced in this reaction is unclear. It may be transported from the periplasm into the cell and enter a glucose utilization pathway in which glucose is converted to pentose [Cohen51] (see D-gluconate degradation) or it might be excreted from the cell [Sashidhar10].

Inhibitors (Unknown Mechanism): EDTA [Hucho72]


References

Cohen51: Cohen SS (1951). "Utilization of gluconate and glucose in growing and virus-infected Escherichia coli." Nature 168(4278);746-7. PMID: 14882337

Hucho72: Hucho F, Wallenfels K (1972). "Glucono- -lactonase from Escherichia coli." Biochim Biophys Acta 1972;276(1);176-9. PMID: 4625870

Sashidhar10: Sashidhar B, Inampudi KK, Guruprasad L, Kondreddy A, Gopinath K, Podile AR (2010). "Highly Conserved Asp-204 and Gly-776 Are Important for Activity of the Quinoprotein Glucose Dehydrogenase of Escherichia coli and for Mineral Phosphate Solubilization." J Mol Microbiol Biotechnol 18(2);109-119. PMID: 20215780


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
Page generated by SRI International Pathway Tools version 18.5 on Thu Dec 25, 2014, biocyc14.