Development of a conventional immunochemical detection system for determination of Nδ-(5-hydro-5-methyl-4-imidazolone-2-yl)-ornithine in methylglyoxal-modified proteins.

Methylglyoxal (MGO) produced during glycolysis is known to react with arginine residues on proteins to generate advanced glycation end products, such as Nδ-(5-hydro-5-methyl-4-imidazolone-2-yl)-ornithine (MG-H1). Since the production of MGO is increased during hyperglycemia or metabolic disorders in vivo, it is considered that the measurement of MG-H1 is useful for evaluating abnormalities in carbohydrate metabolism. Thus, we prepared a monoclonal antibody against MG-H1 to develop a conventional measurement system for MG-H1. Reactivity and specificity of the antibody to MGO-modified protein were confirmed by enzyme-linked immunosorbent assay and western blotting, respectively. The measurement of MG-H1 content by the antibody was positively correlated with that by electrospray ionization-liquid chromatography-tandem mass spectrometry and the ratio of modified arginine residues by amino acid analysis. Our results demonstrated that immunochemical methods could be useful for the estimation of MG-H1 content in modified proteins.