Isolation and properties of bovine colostral trypsin inhibitor.

The trypsin inhibitor of bovine colostrum was isolated by affinity chromatography, and impurities removed by trichloroacetic acid precipitation. The inhibitor showed electrophoretic microheterogeneity which was not due to sialic acid content. It inhibited bovine and rat trypsin, showed weak inhibition of bovine chymotrypsin and was inactive against rat chymotrypsin and bovine renin, kallikrein, thrombin and trypsinogen. The dynamics of secretion of the inhibitor in the first 8 milkings post-partum were very similar to those of colostral immunoglobulins.