The effect of trypsin and chymotrypsin on the antibacterial activity of complement, antibodies, and lactoferrin and transferrin in bovine colostrum.

The effect of trypsin and chymotrypsin on antibacterial factors in bovine colostrum has been studied. Endogenous complement in colostrum was extremely sensitive to both enzymes. IgM was attacked by chymotrypsin but not by trypsin. Trypsin slowly attacked IgG1, causing loss of biological activity due to cleavage of both light and heavy chains. IgG1 was only very slightly attacked by chymotrypsin. Lactoferrin and transferrin in the iron-free state were both susceptible to proteolysis, but the iron saturated forms were more resistant and tended to give rise to stable iron-binding fragments.