Electrophoretic Separation of the Mouse Mammary Tumor Virus2

Abstract

The electrophoretic mobility of B particles at neutral pH was found to be greater than that of any of the main components of milk. This characteristic of the B particles provides a means for their isolation. Relatively large quantities of these particles have been isolated from milk by means of a special electrophoresis tube with pH and density gradients. Particles separated in this manner have a different, possibly less denatured, appearance in the electron microscope from those separated by density gradient ultracentrifugation in concentrated salts. The high mobility of the B particle agrees with the high mobility of milk-agent bioactivity previously reported.