HIGHER TRANSPEPTIDATION ACTIVITY AND BROAD ACCEPTOR SPECIFICITY OF GAMMA-GLUTAMYLTRANSFERASES OF TUMORS

  • 1 January 1976
    • journal article
    • research article
    • Vol. 67  (2) , 215-222
Abstract
The .gamma.-glutamyltransferase (EC-2.3.2.2) (.gamma.-glutamyltranspeptidase, .gamma.-GTP) activity in hepatoma induced by 3''-methyl-4-(dimethylamino)azobenzene (3''-Me-DAB) was 120-fold higher than that of normal liver and high activity was also found in bovine hepatocellular carcinoma. .gamma.-GTPs from these malignant tissues responded more and showed broader specificity to .gamma.-glutamyl group acceptors than those from normal tissue such as bovine, rat and mouse liver and bovine kidney. Three species of .gamma.-GTP were isolated from bovine kidney by DEAE cellulose chromatography, whereas only 2 species were isolated from bovine hepatocellular carcinoma. The carcinoma lacked the least acidic enzyme species. Appropriate .gamma.-glutamyl group acceptors stimulated more acidic enzyme species more than less acidic species in both tissues. The fractions separated from the hepatoma were stimulated more than those of kidney by .gamma.-glutamyl group acceptor. The enzymes from normal tissues responded similarly to a .gamma.-glutamyl group acceptor irrespective of the difference in their activity. .gamma.-GTPs of malignant tissues appear to be more versatile for amino acid transport, qualitatively and quantitatively. In these properties the enzyme of mouse fetal liver which showed the highest activity in the last period of pregnancy resembled the enzymes of malignant rather than normal tissues. The activity of hepatic .gamma.-GTP is not parallel with the rate of cell proliferation during normal development.

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