Size and Configuration of Glycoprotein Fragments Cleaved from Tumor Cells by Proteolysis

Mucin-type glycoprotein material was fractionated by gel filtration after cleavage from viable TA3-Ha mouse mammary adenocarcinoma ascites cells by a modified trypsin. The macromolecular species present in each fraction were characterized by electron microscopy of metal-contrasted replicas as highly asymmetric rods. Investigation of one fraction gave close agreement for length by electron microscopic measurements and for a length calculated for a single polypeptide backbone model from a molecular weight value by short column sedimentation equilibrium, amino acid composition, and percentage of protein. This result supports a single, extended chain configuration for this fraction. With this value of molecular weight per unit length, approximate molecular weights of particles of the other fractions were calculated. Lengths of polypeptide chains varied from 50 nm (55,000 daltons) to greater than 700 nm, suggesting an average molecular weight for one fraction of over 500,000.