Hydrophobic Hydration and Light Transport in α-Synuclein Protein Solutions in the Near-Infrared

Currently, there is increasing interest in identifying the mechanistic characteristics of the α-synuclein amyloid protein aggregation during its early stages. The initiation of amyloid protein incubation was investigated by applying the concepts of hydrophobic hydration in the early-formed protein aggregates and the light transport in the protein samples by using near-infrared light. These are unexplored concepts in amyloid protein aggregation research. Early-formed protein aggregates develop solvent-exposed hydrophobic residue segments, and intramolecular and intermolecular interactions can be identified by hydrophobic hydration, while consecutive intramolecular interactions can cancel this effect. In the light transport within protein samples, at low protein concentrations, the early-formed protein aggregates achieve stability, whereas at higher concentrations, such as those found in neuronal synapses (∼50  µM), the early-formed aggregates continue to develop.