Cereal Chem 46:136 - 144.  |  VIEW ARTICLE
Immunochemical and Disc Electrophoresis Study of Soybean Trypsin Inhibitor SBTIA-2.

N. Catsimpoolas, D. A. Rogers, and E. W. Meyer. Copyright 1969 by the American Association of Cereal Chemists, Inc. 

The immunochemical properties of the soybean trypsin inhibitor SBTIA-2 were studied by double gel diffusion, immunoelectrophoresis, single immunodiffusion, and complement fixation with the use of an antisoybean water-extract serum 106. As little as 0.03 microgram of the inhibitor can be detected by the micro complement fixation method with 400-fold dilution of antiserum. The inhibitor was found to be immunochemically identical with a corresponding protein in the total soybean water extract, and thus it is not an artifact of isolation. Stoichiometric addition of trypsin greatly reduces the antigenic sites of the inhibitor as examined by complement fixation. The single immunodiffusion technique can be used for quantitative estimation of inhibitor in the range of 0.02 to 1.00 mg. of the compound. By disc electrophoresis, impurities present in the commercial preparation of the inhibitor exhibit distinctly different patterns in presence and absence of persulfate catalyst, and in gels of various polyacrylamide concentrations. Microdensitometer tracings of the stained bands showed that the inhibitor contained the following amounts of apparent impurities in gels polymerized as indicated: 4% gels, ammonium persulfate, none; 7%, riboflavin and light, 5%; 7%, ammonium persulfate, 43%; and 11% riboflavin and light, 22%. The possibility of artifact formation caused by the persulfate catalyst is discussed.