Variations in gamma-glutamyl transpeptidase glycosylation and kinetic parameters in cultured liver cells.

Abstract

In rat hepatocytes; the tumorigenic rat liver cell line ARL-16; and the human hepatoma line, Hep G2, 50% of the total gamma-glutamyl transpeptidase (GGT) activity was bound by a Concanavalin-A Sepharose 4B column, calling for alpha-methylmannoside elution (Peak I). Non-binding GGT was distributed between a rapidly eluting Peak II and a slightly retained Peak III. The Km for gamma-glutamyl-p-nitroanalide for either hydrolysis or transpeptidation, or glutathione (GSH) transpeptidation did not vary with peak number or cell type. The GSH hydrolysis Km was essentially constant in Peak I and II GGT. Peak III GGT exhibited a lower Km for GSH hydrolysis with Hep G2 Peak III GGT being the lowest. Peak III GGT increased to 50% of the GGT activity in Hep G2 cells cultured with GSH as the sole cysteine source.

• Authors: M J Meredith
• Journal: Biochemistry international (Biochem Int) Vol. 25 Issue 2 Pg. 321-30 (Sep 1991) ISSN: 0158-5231 [Print] Australia
• PMID: 1686394 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Concanavalin A
• gamma-Glutamyltransferase
• Glutathione
• Cysteine

Topics

• Animals
• Binding Sites
• Carcinoma, Hepatocellular (enzymology)
• Cells, Cultured
• Concanavalin A (metabolism)
• Cysteine (metabolism)
• Glutathione (metabolism)
• Hydrolysis
• Kinetics
• Liver (cytology, enzymology)
• Liver Neoplasms (enzymology)
• Rats
• Tumor Cells, Cultured
• gamma-Glutamyltransferase (metabolism)