Preparation and structural characterization of pre-fibrillar assemblies of amyloidogenic proteins

Accumulating evidence supports the hypothesis that early, soluble, toxic oligomers, rather than the mature fibrils, relate to diverse amyloid disorders and may represent the primary cytotoxic agents in synaptic dysfunction and death in neurodegenerative diseases. Since the amyloid cascade hypothesis has been -investigated for the amyloid β-protein (Aβ), many groups have reported toxic pre-fibrillar assemblies that are involved in diverse amyloid-related diseases. Much experimental evidence suggests that fibrils formed in vitro strongly resemble those in diseased tissues. For example, protofibrillar intermediates detected in vitro and later in vivo exhibit strikingly similar structural and neurotoxic properties. Taken together, these observations indicate that the structural and mechanistic evidences resulting from in vitro studies pertain to the role of protein fibrillogenesis in neurodegenerative diseases. Thus, extensive research has been devoted to produce in vitro oligomers that resemble the original species in vivo and to develop innovative methodologies to characterize the structure and biological activities of these oligomeric assemblies. In this chapter, we will discuss the methods used for structural characterization of oligomeric assemblies. In addition, we will review methods used for preparing different amyloid-like oligomers in vitro.