Molecular Weight Studies on Human Plasminogen and Plasmin at the Microgram Level

With the use of photoelectric scanning optics on the analytical ultracentrifuge molecular weights on human plasminogen and plasmin have been determined at levels as low as 50 µg per ml and as low as 10 µg per ml for the sedimentation coefficient. The results give a molecular weight of 81,000 for human plasminogen and 75,400 for human plasmin. The molecular weight difference has been verified with differential sedimentation equilibrium techniques. The s20, w0 value of human plasminogen and plasmin were determined to be 4.2 S and 3.9 S, respectively.