Peptides and polypeptides are large chains of amino acids linked together by the peptide bond. They are constituent parts of proteins. Many peptides have physiological, immunological, or antibacterial activity. There is still no way to predict how a polypeptide assembles with similar or other polypeptides or proteins in solution. This is a fundamental scientific question and is important for the understanding of protein-protein interactions, protein folding as well as peptide and protein aggregation.
Aggregation of certain proteins (like tau for example) or polypeptides may cause neurodegenerative diseases including Alzheimer’s disease or Huntington and Kennedy diseases. Amyloid-β (Aβ) for example, is a cleavage product of the amyloid precursor protein. Mutations alter the normal way amyloid precursor protein is cleaved, thereby promoting the production of longer amyloid-β species, in particular Aβ42 (a sequence of 42 amino acids). The polypeptides aggregate into oligomers that assemble into fibrils. Compact senile plaques composed of amyloid-β fibrils are associated with pathological changes in the surrounding brain neurons that lead to synaptic loss. Amyloid-β appears to play a key pathogenic role in Alzheimer’s disease. Little is known about the molecular structure of the fibrils and it is yet unclear how to alter the assembled structure once it formed and effort is made to search for molecules that can do it.
We have developed a way for evaluating the dynamic assembly and disassembly processes in fibrils of Aβ (1-40) peptides. We have also investigated the effect of weakly interacting cosolutes of the unfolding conformations of lysozyme, and studied the interactions between tau and microtubules.