Aberrant folding and aggregation of soluble proteins into amyloid-like deposits has been associated to more than 20 known human disorders, including Alzheimer's disease, spongiform encephalopathies and type II diabetes. Recent research has indicated that the early oligomers present prior to amyloid fibril formation represent the most dangerous species to the cell and that their specific conformational properties determine their toxicity. It has been therefore realised that the structural characterization of these oligomers represents a crucial step in the development of treatments for diseases associated with abnormal protein aggregation.This objective, however, presents formidable challenges, due to the transient lifetime and the heterogeneous nature of such oligomeric species. In this fellowship application we propose to exploit the ability of specific antibodies to bind the early oligomeric aggregates of lysozyme in order to characterise structurally the initial steps of its amyoidogenic pathways. The camel single domain antibody, cAb-HUL5, significantly inhibits fibril formation in lysozyme by stabilising dimers or early oligomers, thus effectively preventing them from being incorporated into higher order oligomers and fibrils. These antibody-bound dimers will be characterised by advanced NMR methods and the structural information acquired in this way will subsequently be used in structure calculations.We will thus be able to obtain for the first time an ensemble of structures representing the conformations populated by the antibody-bound dimeric state of lysozyme. The results of this project will clarify important fundamental aspects of the early stages of the processes of fibril formation and aggregation of proteins, and offer a basis for the development of therapeutic strategies for several debilitating diseases associated with protein aggregation.