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Title: Purification structure and stability of voltage-gated sodium channels
Author: Radford, Matthew
ISNI:       0000 0004 2701 6942
Awarding Body: Birkbeck (University of London)
Current Institution: Birkbeck (University of London)
Date of Award: 2009
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Voltage gated sodium channels (VGSC) are integral membrane proteins that selectively transport sodium ions across cellular membranes in response to changes in membrane potential. In vertebrates sodium channels are composed of a pore forming alpha subunit and one or more auxiliary beta subunit. There are a total of nine different alpha subunit isoforms and four known beta subunits. In higher eukaryotes VGSCs are responsible for fast electrical signalling through the propagation of action potentials in excitable cells such as neurons and muscle. Voltage gated sodium channels due to their physiological importance are established drug targets for anticonvulsants, local anaesthetics and antiarrhythmics. They are also the target of a number of naturally produced neurotoxins that form a diverse group of compounds including polypeptides such as scorpion toxins, alkaloids such as veratridine and others such as heterocyclic guanidines. The work of this thesis has been to isolate and purify firstly a higher eukaryotic sodium channel sourced from the electroplax tissue of the eel Electrophorus electricus and secondly a prokaryotic channel (NaChBac) that was over expressed in an E. Coli cell system. Purified channels were biophysically characterised using circular dichroism spectroscopy to analyse secondary structure content. Purified NaChBac was chemically and thermally unfolded using SDS and monitored using CD. The drug mibefradil was able to bind NaChBac and increase its Tm by 4°C. Ligand binding to the Eel channel was also investigated using CD and tryptophan fluorescence to establish if secondary or tertiary structural changes could be observed upon ligand binding.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available