A two-step method for the separation of five different plasma proteins on a preparative scale, which is capable of being extended to allow the separation of other plasma proteins, is described. The proteins separated were fibrinogen, two α1-glycoproteins, albumin and transferrin. The α1-glycoproteins were characterized in terms of electrophoretic mobility, ultracentrifugal and immunological characteristics. By using this method, it was shown that a single sample of plasma could be fractionated to yield purified proteins in sufficient quantity to simultaneously measure the synthesis of the two α1-glycoproteins, albumin and transferrin in the rat with McFarlane9s technique (McFarlane, 1963; Reeve et al., 1963; McFarlane et al., 1965).
