Partial purification of the serum trypsin inhibitor.

The serum trypsin inhibitor has been studied by many investigators since Lansteiner (1) associated it with the albumin fraction by salt fractionation as did Smith and Lindsley (2) by the electrophoretic separation of serum. Both Christensen and MacLeod (3), and MacFarlane and Pilling (4), also associated the trypsin inhibitor with the albumin fraction but differentiated it from the plasmin inhibitor in the globulin fraction. Recently, Jacobsson (5), with block filter paper electrophoresis, described the presence of two trypsin inhibitors in serum. The larger fraction, which was associated with the cul-globulin, inhibited both trypsin and plasmin. Partial purification of these fractions has been tried frequently. Schmitz (6), using the method of Northrup and Kunitz (7) for isolation of the pancreatic trypsin inhibitor, reported a substance which inhibited crystalline trypsin stoichiometrically. Duthie and Lorenz (8)) using the method of Schmitz, obtained a yield of 0.02 per cent of the serum inhibitor. Peanasky and Laskowski (9) were unable to repeat this method. However, with ammonium sulfate fractionation, they reported the partial purification of the inhibitor with a 50-fold purification and a yield of 5 per cent. Further, they found that it was unstable at room temperature at pH values below 3.6, was precipitated by 2.5 per cent trichloroacetic acid, and was not dialyzable. Loomis et al. (10) reported the isolation of antifibrinolysin by ammonium sulfate fractionation but the effect on trypsin was not reported. Boman (II), with an ion exchange resin for separation of serum, described a method which seemed applicable to separation of the serum trypsin inhibitor. The following study is based on this method.