Lactoferrin and Serum Albumin of Human Casein in Colostrum and Milk

Laetoferrin and serum albumin were measured immunologically in human colostrum and milk.Colostrum and milk contained .51___ .11and .19_ .50g of lactoferrin and .043+__ .016and .030-+-.009 g of serum albumin per 100 ml.Precipitated lactoferrin in colostrum and in milk at pH 4.7 was .016_+ .005and .017___ .005g per 100 ml.Precipitated serum albumin was less than 1.5% of total serum albumin in the milk.Acid casein, prepared by repeated isoelectric precipitation, contained 2.5 g of lactoferrin per 100 g protein.Lactoferrin was not detectable immunologically in the major gel electrophoretic components of isoelectric human casein but was located in separate zones near the origin.Data relate to binding of laetoferrin and serum albumin by human casein.