Biophysical Elucidation of Fibrillation Inhibition by Sugar Osmolytes in α-Lactalbumin: Multispectroscopic and Molecular Docking Approaches

Protein aggregation is among the most challenging new frontiers in protein chemistry as well as in molecular medicine and has direct implications in protein misfolding. This study investigated the role of sugar molecules (glucose, fructose, sucrose, and the mixture of glucose and fructose) in protecting the structural integrity of alactalbumin (alpha-LA) against aggregation. The research focused here is the inhibitory capabilities of sugars against alpha-LA fibril formation investigated employing diverse multispectroscopic and microscopic techniques. The aggregation was induced in alpha-LA thermally with a change in concentration. UV-vis spectroscopy, ThT binding assay, Trp fluorescence, Rayleigh scattering, and turbidity assay depicted synchronized results. Further, transmission electron microscopy (TEM) complemented that a mixture of glucose and fructose was the best inhibitor of alpha-LA fibril formation. Inhibition of alpha-LA aggregation by sugar osmolytes is attributed to the formation of hydrogen bonds between these osmolytes, as evidenced by the molecular docking results. This hydrogen bonding is a key player that prevents aggregation in alpha-LA in the presence of sugar osmolytes. This study provides an insight into the ability of naturally occurring sugar osmolytes to inhibit fibril formation and can serve as a platform to treat protein misfolding and aggregation- oriented disorders.