Physicochemical studies on glycation-induced structural changes in human IgG.

Glycation of biomolecules leads to the formation of advanced glycation end products (AGEs). Glycation of immunoglobulin G (IgG) has been implicated in autoimmune diseases such as rheumatoid arthritis (RA). In this study, human IgG was glycated with physiological concentration of glucose. The changes induced in IgG were analyzed by UV, fluorescence, circular dichroism, and Fourier transform infrared (FTIR) spectroscopy; thermal denaturation studies, native, and Sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis. The ketoamine moieties and carbonyl content were also quantitated in glycated IgG. We report structural perturbations, increased carbonyl content, and ketoamine moieties in the glycated IgG. This may interfere with the normal function of IgG and may contribute to initiation of arthritic complications. AGEs damaged IgG may be used as a biomarker for early detection of RA and the associated secondary complications.