Time-resolved fluorescence studies of protein aggregation leading to amyloid formation

Aggregation of soluble polypeptides or proteins into insoluble amyloid fibrils containing the cross-beta structural motif has been observed in the progression of over 20 diseases. Self-assembly mechanisms have been proposed but are not well-established. Recent evidence has shifted some of the focus from amyloid fibrils to prefibrillar amyloidogenic aggregates as the cause of disease symptoms. We used time-resolved non-covalent fluorescence labeling to follow the conformational changes occurring in a model protein (beta-lactoglobulin) during amyloid aggregation. The data was analyzed using a novel model-free globally regularized fitting technique. This reduction of model space allowed for stable fitting and the ability to identify intermediate species. An aggregation model was then proposed. In the second half of this thesis, our attention is shifted to alpha-synuclein (alphaSyn). alphaSyn is the majority protein component of the fibrillar inclusion bodies found in brains of Parkinson's disease patients. We have begun a set of fluorescence lifetime experiments using covalent and non-covalent labeling schemes to elucidate the dynamic, conformational and aggregation properties of alphaSyn.