Identification of beta-aspartylglycine in uremic serum and its toxicity.

An unidentified ninhydrin-positive substance of acidic nature was found in the serum of uremic patients. This substance was isolated from hemodialysate by the methods of ion-exchange chromatography, gel-filtration and paper electrophoresis, and identified as beta-aspartylglycine by amino acid analysis, N-terminal amino acid determination and comparison with authentic sample synthesized in this laboratory. The quantitative determination of beta-aspartylglycine in serum revealed that the serum concentrations of beta-aspartyl-glycine in uremic patients increased much higher than those in normal subjects. The toxicity of beta-aspartylglycine in mice with acute renal failure induced by uranyl acetate was investigated. The mice given more than 1,0 g/kg body weight of beta-aspartylglycine showed behavioral alterations: low response to the stimuli and low activity, and some mice died by the injection of 4.0 g/kg body weight of the peptide. These results suggested that beta-aspartyl-glycine might be a possible factor which influences the development of uremic toxaemia.