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X-ray structure based investigations on the mechanism of pyrrole synthesis catalysed by E. coli 5-aminolevulinic acid dehydratase

Reference	B10143
Principal Investigator / Supervisor	Professor Peter Shoolingin-Jordan
Co-Investigators / Co-Supervisors	Professor Jon Cooper
Institution	University of Southampton
Department	Centre for Biological Sciences
Funding type	Research
Value (£)	198,998
Status	Completed
Type	Research Grant
Start date	01/11/1998
End date	01/11/2001
Duration	36 months

Abstract

The recent determination of the X-ray structure of E. coli 5- aminolevulinic acid dehydratase (porphobilinogen synthase) in our laboratory, with the inhibitor levulinic acid bound, has revealed several candidate amino acids as substrate binding and catalytic residues. Although the enzyme catalyses the dimerisation of two identical substrates, its two binding sites, the A-site and P-site, have very different properties. The P-site employs serine and tyrosine to bind the carboxyl group of the substrate and lysine 247 to form a Schiff base with the ketone group. The nucleophilicity of lysine- 247 is enhanced by a second closely adjacent lysine. The A-site employs two arginines to bind the substrate carboxyl group and an aspartate bind the amino group. Catalysis is probably accomplished by an aspartic acid, a metal bound hydroxide and the two lysines. Using a combination of site-directed mutagenesis, kinetic analysis, substrate/inhibitor binding and X-ray crystallography, these proposals will be tested to elucidate the precise role of each active site residue in the enzyme mechanism.

Summary

unavailable

Committee	Closed Committee - Biomolecular Sciences (BMS)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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