1984 Volume 96 Issue 1 Pages 1-8
A new method for the measurement of urinary dipeptidase activity is described. The action of dipeptidase on L-Ala-L-Ala results in production of an L-alanine, and this amino acid is simultaneously determined by an L-alanine dehydrogenase-diaphorase system. As urinary substances do not affect this reaction, the measurement can be accomplished without prior dialysis. The mean value±S. D. for normals was found to be 12.0±4.4 IU/g of creatinine. Elevated values were found in chronic nephritis (55.9±35.0 IU/g of creatinine, P<0.001 vs. normal), acute nephritis (46.6±29.9 IU/g of creatinine, P<0.001), and nephrotic syndrome (43.3±36.5 IU/g of creatinine, P<0.001). The dipeptidase activity thus measured showed a significant correlation with dipeptidase activity against L-Leu-L-Leu as substrate. On disc polyacrylamide gel electrophoresis, the urinary dipeptidase of a patient with chronic nephritis appeared as one band with similar mobility to human kidney dipeptidase F. Urinary dipeptidase in a patient with chronic nephritis was identical to human kidney dipeptidase on double immunodiffusion analysis.
