Biochemical properties of the high-molecular-weight glycopeptides released from the cell surface of human teratocarcinoma cells.

The present study deals with the biochemical properties of high-molecular-weight glycopeptides isolated from the surface of human teratocarcinoma cells. This cell surface material released by mild trypsin digestion from galactose-labeled human teratocarcinoma cells, Tera I and PA1, was digested extensively with pronase. Most of the resulting glycopeptides were large and were excluded from a Sephadex G-50 column. The properties of these large cell surface glycopeptides isolated from Tera I cells have been examined in detail. It is clear from these experiments that they are neither acidic mucopolysaccharides nor mucin-type glycopeptides with short oligosaccharide chains. Although the glycopeptides are hardly hydrolyzed by beta-galactosidase even after prior digestion with neuraminidase, around 30% of the glycopeptides are depolymerized by treatment with endo-beta-galactosidase from Escherichia freundii. The large cell surface glycopeptides from Tera I cells therefore appear to be very similar to the large glycopeptides seen on mouse embryonal carcinoma cells, which have core structures composed of galactose and N-acetylglucosamine. Like the mouse cell glycopeptides, a fraction of the large glycopeptides from these human cells bind to agarose-conjugated fucose-binding proteins and peanut agglutinin.