Characterization of gamma-GTP in a human pancreatic cancer cell line

Gamma-glutamyl transpeptidase (gamma-GTP) was partially purified from human normal pancreas, pancreatic carcinoma and a human pancreatic cancer cell line, HPC-Y1. The characteristics of gamma-GTP from all three samples appeared to be identical. The estimated molecular weight of samples solubilized with Triton X-100 was 210K and that of bromelain-solubilized gamma-GTP was 110K. On polyacrylamide gel electrophoresis, the main band in both the Triton- and the bromelain-solubilized gamma-GTP of these samples had similar electrophoretic mobility. The percentages binding with concanavalin A were 52%-62%, while on isoelectric focusing the pI values were 3.40-3.45. It was concluded that the heterogeneity of the gamma-GTP isoenzyme could not be identified by either gel filtration or polyacrylamide gel electrophoresis, and it is necessary to investigate the modification of carbohydrate structure on tumor.