Abstract:

The potential of reverse hexagonal mesophases based on monoolein (GMO) and glycerol (as cosolvent) to facilitate the solubilization of proteins, such as insulin was explored. HII mesophases composed of GMO/decane/water were compared to GMO/decane/glycerol/water and GMO/phosphatidylcholine (PC)/decane/glycerol/water systems. The stability of insulin was tested, applying external phys. modifications such as low pH and heat treatment (up to 70°), in which insulin is known to form ordered amyloid-like aggregates (that are assocd. with several neurodegenerative diseases) with a characteristic cross $\beta$-pleated sheet structure. The impact of insulin confinement within these carriers on its stability, unfolding, and aggregation pathways was studied by combining SAXS, FTIR, and AFM techniques. These techniques provided a better insight into the mol. level of the component interplay in solubilizing and stabilizing insulin and its conformational modifications that dictate its final aggregate morphol. PC enlarged the water channels while glycerol shrank them, yet both facilitated insulin solubilization within the channels. The presence of glycerol within the mesophase water channels gave stronger hydrogen bonds with the hosting medium that enhanced the thermal stability of the protein and remarkably affected the unfolding process even after heat treatment (at 70° for 60 min). [on SciFinder(R)]