Physicochemical analysis of poly-L-lysine: An insight into the changes induced in lysine residues of proteins on modification with glucose.

Nonenzymatic glycation of macromolecules, especially proteins, takes place mainly due to hyperglycemia in diabetes mellitus. Increased glycolysis during cancer and inflammation during rheumatoid arthritis also contribute to the process of glycation. As lysine residues of proteins are a potential site for glycation, it could be used as a marker for early glycation induced changes in lysine-rich proteins. In the present study, a lysine polymer was incubated with increasing concentrations of glucose for 24 h, and the early glycation product was evaluated by nitroblue tetrazolium assay. The modified polymer together with unmodified one was characterized by gel electrophoresis and UV, fluorescence spectroscopy. Results of the study clearly demonstrate that structural perturbation in the lysine polymer was caused by the early glycation. Further study on detection of antibodies against theglycated proteins in diseased patients might be helpful in early diagnosis of the disease.