Inverse Correlation between Amyloid Stiffness and Size
Résumé
We reveal that the axial stiffness of amyloid fibrils is inversely correlated with their cross-sectional area. Because amyloid fibrils' stiffness is determined by hydrogen bond (H-bond) density with a linear correlation, our finding implies that amyloid fibrils with larger radial sizes are generally softer and have lower density H-bond networks. In silico calculations show that the stiffness-size relationship of amyloid fibrils is, indeed, driven by the packing densities of residues and H-bonds. Our results suggest that polypeptide chains which form amyloid fibrils with narrow cross sections can optimize packing densities in the fibrillar core structure, in contrast to those forming wide amyloid fibrils. Consequently, the density of residues and H-bonds that contribute to mechanical stability is higher in amyloid fibrils with narrow cross sections. This size dependence of nanomechanics appears to be a global property of amyloid fibrils, just like the well-known cross-β sheet topology.
Mots clés
Hydrogen bonds
beta sheet
Article
amino acid sequence
polypeptide
correlation analysis
controlled study
computer analysis
Mechanical stability
Stiffness
Axial stiffness
Cross sectional area
Global properties
Inverse correlation
Linear correlation
Packing density
Polypeptide chain
Size dependence
Glycoproteins
amyloid protein
hydrogen bond
molecular mechanics
molecular size
protein stability
protein structure
rigidity