Structural modulation of amyloid fibrils and intermediates by glycosaminoglycans. (360G-Wellcome-088563_Z_09_Z)

We propose to explore how the molecular mechanism of assembly of disease-linked amyloid species are influenced by glycosaminoglycans (GAGs). We will focus on two important examples of disease-linked amyloid, namely, amylin, associated with type-2 diabetes mellitus, and Abeta1-40, associated with Alzheimer's disease. Solid-state NMR will be used to compare the structure of oligomeric and fibrillar aggregates formed from isotopically labelled peptides assembled with/without heparan sulphate (HS) a nd various GAG analogues. The key goals are: 1. To determine how the presence of GAGs during fibril growth affects the structure of amyloid protofilaments of Abeta and amylin. 2. To identify and describe in atomistic detail the nature of the molecular recognition event between amyloid fibrils of amylin and Abeta with different structural architectures and the GAGs heparin and heparin sulphate (HS). This will be achieved by measuring couplings between isotope labels strategically placed in the peptide precursors and using novel heparan sulphate derivatives prepared by chemically modification to incorporate isotope labels. 3. To examine the effect of GAGs on the mechanism of assembly of amylin and Abeta into amyloid fibrils by the characterisation of transient oligomeric intermediates trapped using rapid freeze-quench followed by their structural analysis using solid state NMR.