Chromatographic quantification of argpyrimidine, a methylglyoxal-derived product in tissue proteins: Comparison with pentosidine

Methylglyoxal (MG), an a-dicarbonyl compound, can be produced in vivo by se veral metabolic pathways and the Maillard reaction. It reacts rapidly with proteins to form advanced glycation end products or AGEs. We previously iso lated and characterized a blue fluorescent product of the reaction between MG and arginine, which we named argpyrimidine. We found that argpyrimidine was stable to acid hydrolysis, which allowed us to hydrolyze tissue protein s with 6 N act and quantify argpyrimidine by high-performance liquid chroma tography. Here we report argpyrimidine concentrations in human lens and ser um proteins as determined by HPLC. We have also measured pentosidine, a flu orescent AGE derived from pentose sugars, and compared the concentrations o f pentosidine and argpyrimidine. We found two- to threefold higher argpyrim idine concentrations in diabetic serum proteins than in nondiabetic control s (9.3 +/- 6.7 vs 4.4 +/- 3.4 pmol/mg). We found a significant correlation (P 0.0001) between serum protein argpyrimidine and glycosylated hemoglobin. Argpyrimidine concentrations were approximately seven times greater in bru nescent cataractous lenses than in aged noncataractous lenses. Pentosidine concentrations in serum and lens proteins were much lower than argpyrimidin e concentrations; in general, argpyrimidine levels were 10-25 times higher than pentosidine, Results from our study confirm that MG-mediated arginine modifications occur in vivo and provide a method for assessing pro tein-arg inine modification by MG in aging and diabetes. (C) 2001 Academic Press.