PMID:8856065
| Citation |
Jensen, KF and Mygind, B (1996) Different oligomeric states are involved in the allosteric behavior of uracil phosphoribosyltransferase from Escherichia coli. Eur. J. Biochem. 240:637-45 |
|---|---|
| Abstract |
Uracil phosphoribosyltransferase, catalyzing the formation of UMP and pyrophosphate from uracil and 5-phosphoribosyl-alpha-1-diphosphate (PPRibP), was purified from an overproducing strain of Escherichia coli. GTP was shown to activate the enzyme by reducing K(m) for PPRibP by about fivefold without affecting Vmax. When started by addition of enzyme, the reactions accelerated over an extended period of time, while enzyme solutions incubated first with GTP and PPRibP displayed constant velocities. This indicated that PPRibP and GTP influenced the structure of the enzyme. Gel-filtration and sedimentation analyses showed that the apparent oligomeric state of uracil phosphoribosyltransferase is defined by a dynamic equilibrium between a slowly sedimenting form (dimeric or trimeric) that has only a little activity, and a more highly aggregated form (pentameric or hexameric), which is more active. It appears that the smaller form predominates in the absence of substrates, while the larger form predominates in the presence of GTP and PPRibP. Guanosine-3',5'-bis(diphosphate) was found to activate the enzyme much like GTP. |
| Links | |
| Keywords |
Allosteric Regulation; Base Sequence; Cations, Divalent/pharmacology; Centrifugation, Density Gradient; Chromatography, Gel; DNA Primers/genetics; Enzyme Activation/drug effects; Escherichia coli/enzymology; Escherichia coli/genetics; Guanosine Tetraphosphate/pharmacology; Guanosine Triphosphate/pharmacology; Kinetics; Ligands; Models, Molecular; Pentosyltransferases/chemistry; Pentosyltransferases/genetics; Pentosyltransferases/metabolism; Phosphoribosyl Pyrophosphate/pharmacology; Protein Conformation |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
References
See Help:References for how to manage references in EcoliWiki.