Hydrogen-Deuterium Exchange Vibrational Raman Spectroscopy Distinguishes Distinct Amyloid Polymorphs Comprising Altered Core Architecture

Amyloid fibrils are ordered protein aggregates comprisinga hydrogen-bondedcentral cross-beta core displaying a structural diversity in theirsupramolecular packing arrangements within the core. Such an alteredpacking results in amyloid polymorphism that gives rise to morphologicaland biological strain diversities. Here, we show that vibrationalRaman spectroscopy coupled with hydrogen/deuterium (H/D) exchangediscerns the key structural features that are responsible for yieldingdiverse amyloid polymorphs. Such a noninvasive and label-free methodologyallows us to structurally distinguish distinct amyloid polymorphsdisplaying altered hydrogen bonding and supramolecular packing withinthe cross-beta structural motif. By using quantitative molecularfingerprinting and multivariate statistical analysis, we analyze keyRaman bands for the protein backbone and side chains that allow usto capture the conformational heterogeneity and structural distributionswithin distinct amyloid polymorphs. Our results delineate the keymolecular factors governing the structural diversity in amyloid polymorphsand can potentially simplify studying amyloid remodeling by smallmolecules.

Automated summary

Vibrational Raman spectroscopy coupled with hydrogen/deuterium exchange can discern key structural features responsible for diverse amyloid polymorphs. This noninvasive and label-free method allows for the structural differentiation of distinct amyloid polymorphs, capturing conformational heterogeneity and structural distributions. This research provides insights into the molecular factors governing structural diversity in amyloid polymorphs and could potentially simplify the study of amyloid remodeling by small molecules.