Physicochemical properties of human lactalbumin.

Proteins of the same kind in human milk and cow's milk have different properties. Mellander (1947) reports differences in phosphorus content and the amount of carbohydrates of casein and that the casein of cow's milk is more easily digested by proteolytic enzymes in vitro than that of human milk. Kiyosawa, Ryoki & Maeno (1961) observed a marked difference in the solubility of casein and the turbidity created by binding inorganic salts to casein. Deutsch (1947) and Wegelin (1952) showed that there were different electrophoresis patterns of whey protein in human milk and cow's milk. Physical and chemical properties of crystalline fi-lactoglobulin (Palmer, 1934; Sorensen & S0rensen, 1939; Deutsch & Bain, 1948) and a-lactalbumin (Gordon & Semett, 1953) of cow's milk have been studied. Johansson (1958) separated lactalbumin from human milk by calcium phosphate-column chromatography. Casein and lactoglobulins in the whey were removed with ammonium sulphate at 50% saturation, the lactalbumin fraction was then precipitated by saturation with ammonium sulphate and separated into three components (serum albumin, lactalbumin and salmon-coloured component) by calcium phosphate-column chromatography. In the present study, the lactalbumin was prepared from human-milk whey by a method different from that adopted by Johansson.