Thermodynamic properties of amyloid fibrils in equilibrium

Abstract

In this manuscript we use a two-dimensional coarse-grained model to study how amyloid fibrils grow towards an equilibrium state where they coexist with proteins dissolved in a solution. Free-energies to dissociate proteins from fibrils are estimated from the residual concentration of dissolved proteins. Consistent with experiments, the concentration of proteins in solution affects the growth rate of fibrils but not their equilibrium state. Also, studies of the temperature dependence of the equilibrium state can be used to estimate thermodynamic quantities, e.g., heat capacity and entropy.

Exploring the potential of infrared spectroscopy in qualitative and quantitative monitoring of ovalbumin amyloid fibrillation

“…The starting sample has a dominant band at about 45 kDa corresponding to the ovalbumin monomer. After 2 hours of incubation at 90°C, the monomer ovalbumin band is still present which indicates the existence of an equilibrium between fibril forms and soluble protein monomers [36]. The indiscrete electrophoretic pattern with smear in the low-molecular-weight region is likely to be the result of ovalbumin fragmentation at low-pH, high-temperature conditions, as suggested by Lara et al [16].…”

Fluidic Force Microscopy Demonstrates That Homophilic Adhesion by Candida albicans Als Proteins Is Mediated by Amyloid Bonds between Cells

“…The cell-to-cell binding is inhibited by a short antiamyloid peptide. We argue that these sequences mediate the formation of amyloid-like steric zipper β sheet structures. , As in amyloids, these multiple interactions are cooperative, and therefore high local concentrations lead to formation of highly stable structures. , In Als5, both activities are abrogated in the nonamyloid-forming adhesin Als5 V326N (Figure B) or by treatment with antiamyloid compounds. , Consequently, amyloidogenic T regions are under strong positive evolutionary selection . Amyloid-like clustering and strong cellular aggregation are also observed in Als5 Aβ , a form of adhesin in which LVFFA, an amyloid core sequence from human Aβ is substituted for 325 IVIVA 329 .…”

“…41,42 As in amyloids, these multiple interactions are cooperative, and therefore high local concentrations lead to formation of highly stable structures. 43,44 In Als5, both activities are abrogated in the nonamyloid-forming adhesin Als5 V326N (Figure 2B) or by treatment with antiamyloid compounds. 8,9 Consequently, amyloidogenic T regions are under strong positive evolutionary selection.…”

On the Protein Fibrillation Pathway: Oligomer Intermediates Detection Using ATR-FTIR Spectroscopy

“…The widest definition takes oligomers as smaller aggregates containing 2–20 monomer units [ 1 ]. Thus, oligomer is used as a term for a state that excludes 50% of protein molecules in a monomer state and the other case where more than 50% is part of a big cluster [ 4 ]. They continue their route to fibrils by occupying protofibril form—wormlike filamentous late intermediate stage without periodicity in their structure [ 5 , 6 ].…”