Fractionation of Serum with Ammonium Sul- Fate and Water Dialysis, Studied by Electrophoresis

In recent years, there have been several papers dealing with the inhomogeneity of serum globulin and with the possibility of separating homogeneous components of constant and reproducible properties. Hewitt (7, 8) has reported that there are five different proteins, called euglobulin I and II, pseudoglobulin A, globoglycoid, and the “main pseudoglobulin fraction,” the latter not yet exactly defined and still containing impurities of pseudoglobulin A and globoglycoid. Green (3), using isoelectric precipitation, obtained three fractions, called PI, Pm and Pm, two of which have isoelectric points close to pH 5, and one in the neighborhood of pH 6, in good agreement, as the author herself points out, with the electrophoretic components noted by Tiselius (32). Lately Kendall (10) has succeeded in proving the existence of at least five specific antigens in normal human serum globulin. He has been able to prepare the corresponding antisera and has made progress in isolating the antigens. They have been investigated in this laboratory by sedimentation and electrophoresis. The results will be dealt with in a future paper.1 Ultracentrifugal analysis of serum globulin has led to the discovery of three molecular species of serum globulins. The main component has a sedimentation constant of about 7 X 10-13, one, called the X component, has a less well defined sedimentation constant in the neighborhood of that of serum albumin (s = 4.5 X lo-13), and the third is characterized by its very rapid sedimentation (s = 18 20 X lo-13) (Svedberg and Sjijgren (28); von