A Fluorometric Method for Dipeptidase Activity Measurement in Urine, Using L-Alanyl-L-Alanine as Substrate

• Published in: Journal of biochemistry (Tokyo) Vol. 96; no. 1; pp. 1 - 8
• Main Authors: ITO, Yoshimasa, WATANABE, Yoshihito, HIRANO, Kazuyuki, SUGIURA, Mamoru, SAWAKI, Shunji, OGISO, Taro
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.01.1984
• Subjects: Alanine Dehydrogenase; Amino Acid Oxidoreductases - metabolism; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Dihydrolipoamide Dehydrogenase - metabolism; Dipeptidases - urine; Dipeptides - metabolism; Electrophoresis, Disc; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Humans; Hydrolases; Immunodiffusion - methods; Kidney - enzymology; Kidney Diseases - enzymology; Spectrometry, Fluorescence; Substrate Specificity; Human; Urine; Alanine; Hydrolase; Enzyme; Oxidoreductase; Reaction product; Alanine dehydrogenase; Renal disease; Urinary tract disease; Fluorescence spectrometry; Dipeptide; Assay; Enzymatic method; Dipeptidase; Dihydrolipoamide reductase (NAD+); Catalyst activity
• ISSN: 0021-924X; 1756-2651
• DOI: 10.1093/oxfordjournals.jbchem.a134801

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-alanme 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-I.eu-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.