Effect of 33 Hz Pulsed Electric Field on Insulin Amyloidosis

The destabilizing of protein leads to self-aggregation and fibrillar assemblies. In the form of amyloid fibrils or fibril precursors, protein not only lacks the original biological function but also may be harmful to organisms. Stimulated by an intense electric field, the secondary structures of protein can be disturbed and transfer to aggregations or unfolding conformations, which may inhibit the fibrillation process. As a model for disease-associated amyloids, insulin fibrillation is proposed to occur via partial unfolding of a monomeric intermediate. This project is focusing on in-vitro studies employing a 33 Hz pulsed electric field (PEF) to see if there is possible causal connection between insulin fibrillation and PEF exposure. Thioflavin T (ThT)-fluorescence, circular dichroism(CD) and transmission electron microscopy (TEM) techniques were employed regarding the effects of exposure duration and field intensity of the PEF on the fibrillation mechanism of insulin. The results confirm that the PEF exposed insulin molecules may primitively have a slight change in its native structure, causing aggregation. The aggregates in the PEF exposed insulin solution are difficult to dissolve to facilitate the unfolding of insulin molecules. When the molecular conformation converts from alpha-helical to beta-sheet structure, the fibrillation velocity in the PEF exposed insulin is accelerated by the PEF exposure thereby shortening the lifetime of the intermediates. The morphology of mature fibrils changes from long twisted fibrils to shorter and less matured fibrils. All these effects enhance when the exposure duration and electric intensity increase. The investigated evidences suggest that the PEF can inhibit insulin amyloidosis.