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Title: Lysozyme-small molecule interactions
Author: Wadood, Abdul
ISNI:       0000 0001 3549 9196
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1998
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The interaction of hen egg white lysozyme with penicillin and a range of metal ions has been studied using microcalorimetry and related biophysical techniques. UV difference and fluorescence experiments on the binding of penicillin to lysozyme are ambiguous and reflect the variety of published observations, but there is no clear evidence that penicillin competes for example with N-acetylglucosamine (NAG) in the binding cleft. This is supported by ITC binding experiments which suggest that penicillin-G binds to a site on lysozyme remote from the active site. DSC studies are complicated by the thermal instability of penicillin-G in solution above 35°C. The effect is to reduce the apparent Tm for unfolding of lysozyme in a manner that suggests that penicillin or its decomposition products bind preferentially to unfolded protein. This may explain some of the experimental uncertainties apparent in the published data. DSC measurements of the effect of metal ions (mono-, di-, and tri-valent) on the thermal unfolding stability of lysozyme show that, in general, their effect is to reduce the Tm , sometimes with aggregation of the unfolded protein, consistent with metal ion binding to exposed groups on the unfolded polypeptide. The effect of Al3+ ions has been explored in some detail. The interaction of lanthanide ions (La3+ and Eu3+) has also been studied by DSC, ITC and fluorescence methods. ITC in particular shows multiple binding sites for lanthanide ions on lysozyme, some of which compete with NAG binding. This is consistent with lanthanide ion binding to some of the carboxylate residues on the protein, including those in the active site.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Benzyl penicillin; Protein folding