Characterization of advanced glycation end products and aggregates of irisin: Multispectroscopic and microscopic approaches

Abstract

Glycation of proteins leading to the formation of advanced glycation end products (AGEs) has been demonstrated to contribute to the pathogenesis of several diseases. Irisin is a clinically significant protein, putatively involved in obesity, diabetes, and neurological disorders. This study aimed to monitor the methyl-glyoxal (MG) induced AGEs and aggregate formation of irisin, as a function of time, employing multispectroscopic and microscopic approaches.ANS fluorescence suggested a molten globule-like state on Day 6, followed by the formation of irisin AGEs adducts, as confirmed by AGE-specific fluorescence. Glycation of irisin led to aggregate formation, which was characterized by Thioflavin T fluorescence, CD spectroscopy, and microscopic studies. These aggregates were confirmed by exploiting fluorescence microscopy, confocal, and transmission electron microscopy. Molecular docking was performed to determine the crucial residues of irisin involved in irisin-MG interaction. Usually, MG is present in trace amounts as a metabolic by-product in the body, which is found to be elevated in diseased conditions viz. diabetes and Alzheimer's disease. This study characterized the AGEs and aggregates of clinically important protein, irisin; and since MG level has been found to be increased in various pathological conditions, this study provides a clinical perspective. There is a possibility that elevated MG concentrations might glycate irisin resulting in reduced irisin levels as reported in pathological conditions. However, further investigations are required to prove it.

Understanding the Modulation of α-Synuclein Fibrillation by N-Acetyl Aspartate: A Brain Metabolite

“…35 Three independent ThT fluorescence measurements of the sample were taken by a Jasco FP-8200 fluorescence spectrometer with an excitation wavelength of 440 nm and the emission wavelength in the range of 450−600 nm. 36 All of the measurements were taken in triplicate with an error of less than 4%. Aggregation parameters (T agg , T lag , and b) were analyzed through eq 1 using a nonlinear regression method using Sigma plot 10.0.…”

“…Three independent ThT fluorescence measurements of the sample were taken by a Jasco FP-8200 fluorescence spectrometer with an excitation wavelength of 440 nm and the emission wavelength in the range of 450–600 nm . All of the measurements were taken in triplicate with an error of less than 4%.…”