Biophysical Analysis of the Structure and Aggregation of Amyloid beta Peptide

Alzheimer\u27s disease (AD) is the major cause of dementia and is characterized by neuronal death and brain atrophy. The amyloid ß (Aß) peptide is tightly associated with neuronal dysfunction during AD, but the molecular mechanism underlying the neurotoxic effect of Aß is poorly understood. Extracellular fibrillar deposits (plaques) of Aß were initially believed to be the cause of AD, but currently there is overwhelming evidence that the prefibrillar Aß oligomers are the major toxic entities. Structural characterization of Aß oligomers and fibrils is important for understanding the structural features determining the toxic potency of the peptide. This project has studied the aggregation and accompanying structural transitions of Aß, a naturally occurring hypertoxic species, i.e. pyroglutamylated Aß, and their combination, using biophysical approaches (circular dichroism, fluorescence, infrared spectroscopy). In addition, aggregation and structure of overlapping peptide fragments have been studied to identify the specific stretch of Aß that serves as seeding region initiating the aggregation and fibril formation by the full-length Aß peptide. These studies elucidate the structural features of Aß responsible for the peptide\u27s neurotoxic actio