Serum and liver glycylproline dipeptidyl aminopeptidase activity in rats with experimental hepatic cancer.

Changes of glycylproline dipeptidyl aminopeptidase (GPDA) and gamma-glutamyl transpeptidase (gamma-GTP) activities were compared in the serum and liver tissue of rats with hepatic cancer induced by 3'-methyl DAB. Serum glycylproline dipeptidyl aminopeptidase activity in rats with the azo dye-induced hepatic cancer was significantly higher than that in healthy rats, but the increase was not so extensive compared with that of gamma-glutamyl transpeptidase. The specific activity of glycylproline dipeptidyl aminopeptidase was decrease in the microsomal fraction and increased in the supernatant fraction of hepatic cancer tissue, whereas that of gamma-glutamyl transpeptidase was increased in both microsomal and supernatant fractions. These results suggest that the mechanisms, whereby serum activities of these two enzymes were increased in rats with hepatic cancer, were different from each other.