Alpha-lactalbumin and beta-lactoglobulin as the bioactive compounds of the milk protein fraction

摘要

The purpose of the study was to present the latest data concerning the chosen bioactive compounds of the milk protein fraction. The numerous experiments that have been conducted during the last few years suggest that milk contains a great deal of biologically active substances. Among them the whey proteins perform a particular function. Their content in bovine milk is 0.6-0.7% of total protein, in that about 75% generally accounts for the albumins, i.e. alpha-LA and beta-LG. These proteins, as a uniquely rich and balanced source of amino acids, possess a significant meaning for human nutrition. a-LA consists of 123 amino acids in a single peptide chain and among them the most crucial are: cysteine and tryptophan, which are adequately the equivalents of glutathione and serotonin, as well as lysine. a-LA occurs in bovine milk at the concentration of 1-1,5 g.L-1. Whereas the beta-LG single peptide chain consists of 162 amino acids, including methionine, the indispensable component of rational nutrition. It has also been reported that the concentration of beta-LG is approximately 3,2-3,5 g.L-1. The higher level of these proteins has been stated in the milk from cows fed mainly pasture forage. In addition to this, the mentioned bovine milk fractions perform various biological functions in the human body, i.e. anti-oxidative, anti-carcinogenic, opioidergic, bacteriostatic as well as hypocholesterolemic functions.