Carnosine Prevents the Glycation-induced Changes in Electrophoretic Mobility of Aspartate Aminotransferase
Journal of Biochemical and Molecular Toxicology
Carbohydrate-derived aldehydes cause irreversible loss of protein function via glycation. We previously observed that glyceraldehyde 3-phosphate (Glyc3P) abolishes the enzyme activity of cardiac aspartate aminotransferase (cAAT). We also examined the protective effects of carnosine against Glyc3P-induced loss of enzyme activity. The present study looked at carnosine's prevention of Glyc3P-induced change in protein structure. Purified cAAT (2 mg protein/mL) was incubated with various concentrations of carnosine (1-20 mM) in the presence of Glyc3P (500 microM) for 4 days at 37 degrees C. Following incubation, samples were analyzed by SDS-polyacrylamide gel electrophoresis. Carnosine showed prevention of protein modification at carnosine-to-Glyc3P ratios of 10:1 or greater. There was a progressive loss of the unmodified cAAT protein band as Glyc3P concentration was increased. Additionally, the gel position of the Glyc3P-modified cAAT protein varied over time. The apparent molecular weight (MWapp) of the Glyc3P-modified cAAT protein that formed after 1 day at 37 degrees C (500 microM) was greater than its MWapp after 2 days, suggesting that a chemical rearrangement of the initial adduct occurs. These observations support the hypothesis that carnosine is an antiglycation agent and that its mechanism of action involves prevention of protein modification.
Seidler NW. Carnosine Prevents the Glycation-induced Changes in Electrophoretic Mobility of Aspartate Aminotransferase. Journal of Biochemical and Molecular Toxicology. 2000; 14(4). doi: 10.1002/(sici)1099-0461(2000)14:4<215::aid-jbt6>3.0.co;2-z.