Fibrillar state

D.A. Slatter, N.C. Avery, A J. Bailey, Collagen in its Fibrillar State is Protected from Glycation, The International Journal of Biochemistry Cell Biology, 40(10), 2253 2263 (2008). 

Refolding models propose that the fibril-forming protein exists in two distinct states the native state and the fibrillar state (Fig. 2). In converting from one to the other, the protein must unfold, then refold. As the fibrillar state is common to proteins with dissimilar sequences, Fandrich et al. (2001) have suggested that refolding into fibrils is dominated by backbone interactions, which are available to all protein sequences. 

This direct-stacking model (Olofsson et al., 2004 Serag et al., 2002) therefore proposes that TTR maintains much of its native structure, including the native dimer interface, in the fibrillar state. A new interaction interface is gained with the shifting of /(-strands at the ends of two sheets, driving fibril formation. 

We have also begun to structurally characterize fibrillar states of a-synuclein (140 residues) and of the K19 domain of protein tau. Both systems are involved in possibly related neuro-degenerative diseases.Preliminary results of two- and three-dimensional correlation spectroscopy, as outlined above, reveal that many of the NMR detectable resonances exhibit narrow or line widths, consistent with the occurrence of well-ordered domains in both proteins. On the other hand, other segments of the considered proteins cannot readily be detected suggesting that they may display static or dynamic disorder under the experimental conditions considered. While the effect of molecular dynamics of NMR relaxation parameters has been studied in the context of solution- or solid-state NMR for a long time, recent progress in the study of uniformly labelled proteins by MAS NMR has created novel means by which to study dynamics of entire polypeptide sequences using 2D methods. For example, Bockmann and Emsley have... 

The general different interaction of amorphous and crystalline regions in the initial (spherulitic) as well the highly stretched (fibrillar) state was investigated with DMA. The stretched material was produced by hot-stretching of small tensile samples from plates with a thickness of 4 mm and 10 mm width at different temperatures. 

Fig. 10.27. Order parameters IJiio, l haio associated with the orientational distributions of the normals on the chain direction within the crystalline and the amorphous regions. The final values refer to the fibrillar state [125]...

Jelinski and Torchia and Torchia and VanderHart have used double-resonance techniques to investigate the mobility of the collagen peptide backbone in solution and the fibrillar state. Specifically, collagen samples... 

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