Inhibition by concanavalin A as the basis for a specific assay of serum 5'-nucleotidase activity.
Concanavalin A inhibits serum 5'-nucleotidase activity, without causing significant inhibition of alkaline phosphatase activity. This observation serves as the basis for a new method for assaying the 5'-nucleotidase activity in serum, which depends upon the difference between the enzymic hydrolysis of adenosine-5'-monophosphate in the presence and absence of concanavalin A. A denosine released by the 5'-nucleotidase reaction is deaminated by a coupled reaction with adenosine deaminase to liberate inosine and ammonia, and ammonia is measured colorimetrically by the Berthelot reaction. In sera from 40 healthy adult persons, 5'-nucleotidase activity averaged 6.4 U/liter (SD, +/-2.0; range, 3-12). In sera from 100 patients, measurements of 5'-nucleotidase activity by the new assay averaged 8% lower than by a generally accepted method in which phenyl phosphate is used to suppress hydrolysis of adenosine-5'-monophosphate by alkaline phosphatase activity. The clinical validy of the new assay was tested by measuring serum 5'-nucleotidase activities in rats with bile duct ligation and in rats treated with thioacetamide to induce hepatocellular injury.
D000328:Adult; D000368:Aged; D003208:Concanavalin A / Q000494:pharmacology*; D005260:Female; D006461:Hemolysis; D006801:Humans; D007202:Indicators and Reagents; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008722:Methods; D008875:Middle Aged; D009708:Nucleotidases / Q000037:antagonists & inhibitors / Q000097:blood*; D013053:Spectrophotometry / Q000379:methods
D007202:Indicators and Reagents; D003208:Concanavalin A; D009708:Nucleotidases; D008274:Magnesium