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Title: Towards the control of the morphology of amyloid fibres displaying electron transfer enzymes
Author: Forman, C. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2010
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One possibility for controlling the high density organisation of enzymes for technological purposes, which could increase human use of sunlight and absorb atmospheric CO2, would be to decorate amyloid fibres with functional enzymes. Therefore several multi-domain fusion proteins were made which consisted of permutations of the SH3 fibre forming domain and cytochrome b562—an electron transfer domain whose native state is stabilised when it binds the electron transfer cofactor ferrous proto-porphyrin IX (also known as haem). It was anticipated that these fusion proteins would form fibres displaying the electron transfer enzymes and would be capable of transporting charge along the complete length of the fibre. To understand the organisation of the proteins in a fibre, at a molecular level, a variety of experimental and theoretical approaches were required. High resolution AFM under liquid found that the surface roughness of the fibre depended on the species under consideration, the quantity of haem bound by the cytochromes and also confirmed the dimensions and number of filaments within each fibre species. A key observation from preliminary work—that only half of the fibre-borne cytochromes can bind haem—was confirmed and extended to all the fibre forming proteins studied. The haem binding improves the imaging properties of the fibre and changes the morphology in a systematic way, thus yielding small molecule control over the fibre morphology which, in principle, could be used to bring the displayed cytochromes into adequate proximity for electron transfer to occur. The improved imaging arising from haem binding allowed the high resolution AFM tip to penetrate deeper into the fibre. The existence of an inner filament linked to surface moieties was confirmed and the best information possible was used to create a model of the fibre.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available