H2S‐Induced Structural Changes of Insulin Protein in Early Lag Phase: Key to Detaining Amyloid Formation

Abstract

Amyloid fibrils are formed by soluble proteins that assemble into insoluble fibers associated to many types of diseases such as Diabetes Type 2, and Alzheimer's Disease. Amyloid formation can be divided into three phases: the lag phase, where native protein unfolds and begins to self‐aggregate; the elongation phase, in which these aggregates grow into fibrils, and the steady phase, where saturation of mature fibrils occurs. Hen egg white lysozyme (HEWL) amyloid fibrils are inhibited in the presence of hydrogen sulfide (H2S) (Rosario, 2014). To further explain the means by which H2S inhibits amyloid fibrillation, insulin from bovine pancreas (IBP), was tested upon experimentation with increasing concentrations of H2S. ThT Fluorescence analysis revealed a decrease in peak intensity as the concentration of H2S increased in each sample, proving H2S to be an inhibitor of insulin amyloids. Atomic Force Microscopy (AFM) of the control sample showed an array of fibrillary structures. However, as the concentration of H2S increased, samples went from having a combination of fibrillary structures and small conglomerated spherules to the sole appearance of small spherules. Far UV‐Circular Dichroism spectra of the native protein and the protein interacting with H2S were very similar. However, non‐resonance Raman spectra revealed the presence of newly formed trisulfide bridges in the interaction between insulin and the H2S species as opposed to the disulfide bridges found in native and fibrillated insulin protein. The data suggest H2S‐protein interactions favor a structural change in the process of protein denaturing. The H2S species intervenes with amyloid formation early on during the lag phase inhibiting the formation of protofibrils and potential mature fibrils.Support or Funding InformationResearch reported in this publication was supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under grant number P20GM103475. It was also supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number T34GM008419. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.