Physico-chemical Changes Induced in the Serum Proteins Immunoglobulin G and Fibrinogen Mediated by Methylglyoxal.

Abstract

Non-enzymatic glycation of proteins plays a significant role in the pathogenesis of secondary diabetic complications via the formation of advanced glycation end products (AGEs) and increased oxidative stress. Methylglyoxal (MG), a highly reactive dicarbonyl of class α-oxoaldehyde that generates during glucose oxidation and lipid peroxidation, contributes to glycation. This comparative study focuses on methylglyoxal induced glycoxidative damage suffered by immunoglobulin G (IgG) and fibrinogen, and to unveil implication of structural modification of serum proteins in diabetes-associated secondary complications. The methylglyoxal induced structural alterations in IgG and fibrinogen were analyzed by UVvis, fluorescence, circular dichroism and Fourier transform infrared (FT-IR) spectroscopy. Ketoamine moieties, carbonyl contents, 5-Hydroxymethylfurfural (HMF) and malondyaldehyde were also quantified. Free lysine and arginine estimation, detection of non-fluorogenic carboxymethyllysine (CML) and fibril formation were confirmed by thioflavin T (ThT) assay. Structural alterations, increased carbonyl contents and ketoamines were reported in MG glycated IgG and fibrinogen against their native analogues. The experiment results validate structural modifications, increased oxidative stress and AGEs formation. Thus, we can conclude that IgG-AGEs and Fib-AGEs formed during MG induced glycation of IgG and fibrinogen could impede normal physiology and might initiates secondary complications in diabetic patients.