Structural Characterization of GNNQQNY Amyloid Fibrils by Magic Angle Spinning NMR.
 

Structural Characterization of GNNQQNY Amyloid Fibrils by Magic Angle Spinning NMR.

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Biochemistry. 2010 Aug 9;

Authors: van der Wel PC, Lewandowski JR, Griffin RG

Various human diseases feature the formation of amyloid aggregates, but experimental characterization of these amyloid fibrils and their oligomeric precursors has remained challenging. Experimental and computational analysis of simpler model systems has therefore been necessary, for instance on the peptide fragment GNNQQNY7-13 of yeast prion protein Sup35p. Using magic angle spinning (MAS) NMR we have recently shown that the GNNQQNY fibrils contain three distinct peptide conformations. Using distance and backbone torsion angle measurements we characterize the basic structure of these co-existing conformers, two of which adopt parallel in-register beta-sheets. The third conformer also forms a parallel in-register sheet-like structure, but features increased dynamics and a local beta-bulge-like conformation. Our data suggest that each of the conformers is present in its own parallel sheet, within the fibril. Our experiments also indicate a substantial structural difference between the fibrillar and crystalline forms of these peptides, with clearly an increased complexity in the assembly of the fibrillar form. These observations are examined in the context of the computational studies on this model system, in an attempt to integrate the results of both approaches. We hope that our experimental data can inform future theoretical work and provide insights into the distinction between fibril growth and crystal formation.

PMID: 20695483 [PubMed - as supplied by publisher]



Source: PubMed