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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
7
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pubmed:dateCreated |
2003-2-19
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pubmed:abstractText |
UDP-galactopyranose mutase is a flavoprotein which catalyses the interconversion of UDP-galactopyranose and UDP-galactofuranose. The enzyme is of interest because it provides the activated biosynthetic precursor of galactofuranose, a key cell wall component of many bacterial pathogens. The reaction mechanism of this mutase is intriguing because the anomeric oxygen forms a glycosidic bond, which means that the reaction must proceed by a novel mechanism involving ring breakage and closure. The structure of the enzyme is known, but the mechanism, although speculated on, is not resolved. The overall reaction is electrically neutral but a crypto-redox reaction is suggested by the requirement that the flavin must adopt the reduced form for activity. Herein we report a thermodynamic analysis of the enzyme's flavin cofactor with the objective of defining the system and setting parameters for possible reaction schemes. The analysis shows that the neutral semiquinone (FADH(*)) is stabilized in the presence of substrate and the fully reduced flavin is the anionic FADH(-) rather than the neutral FADH(2). The anionic FADH(-) has the potential to act as a rapid 1-electron donor/acceptor without being slowed by a coupled proton transfer and is therefore an ideal crypto-redox cofactor.
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Feb
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pubmed:issn |
0006-2960
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
25
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pubmed:volume |
42
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
2104-9
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:12590598-Bacterial Proteins,
pubmed-meshheading:12590598-Benzoquinones,
pubmed-meshheading:12590598-Electron Spin Resonance Spectroscopy,
pubmed-meshheading:12590598-Enzyme Stability,
pubmed-meshheading:12590598-Free Radicals,
pubmed-meshheading:12590598-Intramolecular Transferases,
pubmed-meshheading:12590598-Kinetics,
pubmed-meshheading:12590598-Klebsiella pneumoniae,
pubmed-meshheading:12590598-Ligands,
pubmed-meshheading:12590598-Oxidation-Reduction,
pubmed-meshheading:12590598-Potentiometry,
pubmed-meshheading:12590598-Quinones,
pubmed-meshheading:12590598-Substrate Specificity,
pubmed-meshheading:12590598-Thermodynamics,
pubmed-meshheading:12590598-Uridine Diphosphate Galactose
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pubmed:year |
2003
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pubmed:articleTitle |
Potentiometric analysis of UDP-galactopyranose mutase: stabilization of the flavosemiquinone by substrate.
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pubmed:affiliation |
Centre for Biomolecular Sciences, The University, St. Andrews KY16 9ST, UK.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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