Amide proton solvent protection in amylin fibrils probed by quenched hydrogen exchange NMR.
 

Amide proton solvent protection in amylin fibrils probed by quenched hydrogen exchange NMR.

http://www.bionmr.com//www.ncbi.nlm....one_120x30.png http://www.bionmr.com//www.ncbi.nlm....pubmed-pmc.gif Related Articles Amide proton solvent protection in amylin fibrils probed by quenched hydrogen exchange NMR.

PLoS One. 2013;8(2):e56467

Authors: Alexandrescu AT

Abstract
Amylin is an endocrine hormone that accumulates in amyloid plaques in patients with advanced type 2 diabetes. The amyloid plaques have been implicated in the destruction of pancreatic ?-cells, which synthesize amylin and insulin. To better characterize the secondary structure of amylin in amyloid fibrils we assigned the NMR spectrum of the unfolded state in 95% DMSO and used a quenched hydrogen-deuterium exchange technique to look at amide proton solvent protection in the fibrils. In this technique, partially exchanged fibrils are dissolved in 95% DMSO and information about amide proton occupancy in the fibrils is determined from DMSO-denatured monomers. Hydrogen exchange lifetimes at pH 7.6 and 37°C vary between ~5 h for the unstructured N-terminus to 600 h for amide protons in the two ?-strands that form inter-molecular hydrogen bonds between amylin monomers along the length of the fibril. Based on the protection data we conclude that residues A8-H18 and I26-Y37 comprise the two ?-strands in amylin fibrils. There is variation in protection within the ?-strands, particularly for strand ?1 where only residues F15-H18 are strongly protected. Differences in protection appear to be due to restrictions on backbone dynamics imposed by the packing of two-layers of C2-symmetry-related ?-hairpins in the protofilament structure, with strand ?1 positioned on the surface and ?2 in the interior.


PMID: 23457571 [PubMed - indexed for MEDLINE]



More...