Separation of a Mouse Growth Inhibitor in Soybeans from Trypsin Inhibitors

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Abstract
Raw (unheated) soybean meal was subjected to numerous physical and chemical treatments in efforts to isolate a growth inhibitor fraction which was free of trypsin inhibitor (TI) activity. Each treatment fraction was added to the diet of growing mice and growth inhibitor activity determined by comparing their growth rates to growth rates achieved on an autoclaved soybean meal diet. A small molecular weight growth inhibitor was separated from TI by ion exclusion chromatography on a Sephadex G-50 column and partially characterized. This growth inhibitor fraction decreased weight gains and feed efficiencies without causing pancreatic enlargement. Evidence of the small size of this growth inhibitor includes removal by dialysis, retardation on a Sephadex G-25 column, and lack of detection by polyacrylamide-gel electrophoresis. High voltage electrophoresis at pH 3.5 indicated the presence of at least eight positively charged peptides in this fraction, one of which may be a glycopeptide.