Inhibition by lactoferrin and kappa-casein glycomacropeptide of binding of Cholera toxin to its receptor.

Inhibition from binding of Cholera toxin (CT) to Chinese hamster ovary (CHO)-K1 cells and ganglioside GM1 by lactoferrin (Lf) and kappa-casein glycomacropeptide (GMP) from cow's milk was examined. Both Lf and GMP effectively reduced the CT-derived morphological changes in CHO-K1 cells. The competitive binding assay demonstrated that both Lf and GMP inhibited the binding of CT to GM1, although their affinity for CT was lower than that of GM1. The inhibitory effect of Lf and GMP seemed to be attributed to their terminal sialic acid, although the sugar chain sequence only partially fitted to the CT-receptor.

Effects of addition of arginine, cystine, and glycine to the bovine milk-simulated amino acid mixture on the level of plasma and liver cholesterol in rats.

The effects of the addition of varying levels of arginine (Arg), cystine (Cys), and glycine (Gly) to the bovine milk-simulated amino acid mixture on the levels of plasma and liver cholesterol were investigated in rats. The diets containing a high amount of Cys lowered significantly the level of plasma cholesterol as the amount of Cys in diets increased. The serum high density lipoprotein (HDL)-cholesterol level and fecal excretion of acidic steroids were higher in rats fed the Cys diets than in those fed the Arg and Gly diets. No differences, however, was observed in the content of liver cholesterol. Liver triglyceride contents elevated significantly on feeding the Arg and Cys diets. Furthermore, liver phospholipid contents elevated significantly on feeding the Arg diet but lowered on feeding the Cys diet. Therefore, these results indicated that the feeding of a high amount of Cys lowers the plasma cholesterol levels as the result of the enhanced conversion of cholesterol to bile acids.