γ-Glutamyltranspeptidase activity in a human pancreatic cancer cell line (HPC-Y1) in serum-free chemically defined medium

γ-Glutamyltranspeptidase (γ-GTP) activity was found in a human pancreatic cancer cell line, HPC-Y1, cultivated in a serum-free chemically defined medium. The γ-GTP stained in the cytoplasms as fine granules and was produced constantly in a protein-free chemically defined medium. The detergent- or protease-solubilized γ-GTP of HPC-Y1 cells in serum-free medium was compared with the γ-GTPs extracted from HPC-Y1 cells in serum-containing medium, human pancreatic carcinoma and normal human pancreas. Their molecular weights, electrophoretic mobilities, affinity to Concanavalin A-Sepharose and isoelectric points were almost identical. No cancer specific properties in the γ-GTP derived from human pancreatic carcinoma cell line were found by these analyses. However, the serum-free spent medium of HPC-Y1 cells was useful for purifying the γ-GTP secreted from the human pancreatic carcinoma cell line, since it is not necessary to separate the contaminated serum components that are usually added for cell cultures and the extraction procedures could induce minor structural change and/or artificial modification of γ-GTP.