Solvent-Driven Dynamical Crossover in the Phenylalanine Side-Chain from the Hydrophobic Core of Amyloid Fibrils Detected by ²H NMR Relaxation.

ABSTRACT: Aromatic residues are important markers of dynamical changes in proteins' hydrophobic cores. In this work we investigated the dynamics of the F19 side-chain in the core of amyloid fibrils across a wide temperature range of 300 to 140 K. We utilized solid-state ²H NMR relaxation to demonstrate the presence of a solvent-driven dynamical crossover between different motional regimes, often also referred to as the dynamical transition. In particular, the dynamics are dominated by small-angle fluctuations at low temperatures and by π-flips of the aromatic ring at high temperatures. The crossover temperature is more than 43 degrees lower for the hydrated state of the fibrils compared to the dry state, indicating that interactions with water facilitate π-flips. Further, crossover temper

SUBMITTER: Vugmeyster L 

PROVIDER: S-EPMC5567839 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature