Carnosine prevents the glycation-induced changes in electrophoretic mobility of aspartate aminotransferase.
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
N W
NW
University of Health Sciences, Department of Biochemistry, Kansas City, MO 64106-1453, USA. NSEIDLER@fac1.uhs.edu
D001219:Aspartate Aminotransferases / Q000378:metabolism*; D002336:Carnosine / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D005947:Glucose / Q000378:metabolism*
D002336:Carnosine; D001219:Aspartate Aminotransferases; D005947:Glucose