| Summary: | Circular dichroism spectroscopy is an established technique that is frequently used in the analysis of the confonnation of biological molecules. It has previously been reported that the deconvolution of circular dichroism spectra of vertebrate eye lens P'rcrystallin proteins gives exceptionally poor results, and that these spectra are heavily influenced by aromatic contributions in the far-ultraviolet. This thesis describes work undertaken to assess to what extent circular dichroism spectra of py-crystallins can be rationalised in tenus of secondary structure, and to determine if circular dichroism can be applied to investigations of the role of crystallin proteins in congenital and agerelated cataract. It Was found that in most py-crystallin spectra, aromatic interference is minor, and that the reported poor quality of py-crystallin deconvolution reflects inherent diffiCulties in deconvolution for most non-helical secondary structures. An instance of aromatic contributions to the far .. ultraviolet spectrum was identified, and investigated through mutagenesis. Synchrotron radiation circular dichroism was used in conjunction with other solution techniques to demonstrate that a loss in solubility of the folded P23T mutation of human yD .. crystallin is responsible for the congenital cataracts associated with this mutation. Finally, circular dichroism was used to investigate the stability and aggregation mechanisms of human fJB2-crystallin, and an assay method developed to show the interaction of fJB2-crystallin with the a.-crystallin molecular chaperone. Information from these experiments was used to describe the unfolding and subsequent aggregation and. chaperone-association of human PB2-crystallin.
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