Bradford, Veronica Qing (1991) Electrochemical studies of modified redox enzymes. PhD thesis, University of Warwick.

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Abstract

In this thesis, methods for enzyme modification and electrochemical studies of modified redox enzymes are described. The modification methods are presented in terms of covalent and non-covalent processes.

Detailed studies are presented for covalently modified glucose oxidase with redox mediators based on ferrocenes. A good understanding is obtained for the kinetics of direct electron transfer between GOx modified with ferroceneacetic acid and a metallic electrode. An estimation for the number of electrons transferred and the diffusion coefficient of this modified enzyme was achieved using combined results from cyclic voltammetry and rotating disc voltammetry studied. The catalytic activity of this modified enzyme was investigated and the data were analysed using our theoretical model. The model includes the reactions between the modified enzyme and the substrate, the reoxidation of enzyme by the attached mediators and the regeneration of the mediators at the electrode. This model is fully explained in Chapter III.

The stabilities of glucose oxidase modified with ferrocenes were investigated by entrapping the modified enzyme behind a dialysis membrane. A direct correlation is established between the stabilities of the ferrocenes and the corresponding modified enzymes.

A novel enzyme modification method, non-covalent modification, is described. The catalytic activities of glucose oxidase modified with several hydrophobic mediators were studied and the determinations of the amount of mediators incorporated within the enzyme were also carried out.

A further investigation of the molecular interaction between mediators and proteins is demonstrated for the model system of TTF in aqueous/BSA media. The oxidation of TTF in a BSA solution was studied and the results were analysed.

Finally, the overall conclusions and possible future directions of this project are given.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Enzymes -- Analysis, Electrochemical analysis, Biochemistry, Oxidoreductases, Ferrocene, Glucose
Official Date:	October 1991
Dates:	Date Event October 1991 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bartlett, Philip N. (Philip Nigel), 1956-
Sponsors:	MediSense ; University of Warwick. Department of Chemistry
Format of File:	pdf
Extent:	xxi, 265 leaves : illustrations, charts
Language:	eng

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