The whey proteins of human milk have important nutritional and physiological roles for the breast-fed infants. Approximately 75% of the whey proteins have been identified. The remaining 25% consists of proteins of physiological significance, necessitating further characterization. In this study, mature milk (M) and colostrum (C) samples were quantified for total N, total protein, whey protein, and non-protein N (NPN) using Kjeldahl analysis and Bio-Rad protein determination. Contents of the major whey proteins, lactoferrin (Lf), secretory IgA (sIgA), α-lactalbumin (LA), lysozyme (Lys), and serum albumin (SA) were determined by immunoelectrophoresis and immunodiffusion. Total N for M and C was 1.6 and 3.2 mg/ml, with NPN values of 0.34 and 0.64 mg/ml. Whey protein in M was 6.7 and in C 18.1 mg/ml. Values for M whey proteins were 1.60, 0.81, 1.97, 0.18 ad 0.52 mg/ml for Lf, sIgA, LA, Lys, and SA, respectively, with C whey values of 7.75, 4,89, 2,54 , 0.10, and 0.37. Thus the mature whey consists of 75.7% major proteins, leaving 24.3% minor proteins, and 86.5% major and 13.5% minor proteins in C. For further characterization of the minor protein fraction, immunoaffinity chromotography was applied to obtain a whey sample devoid of the major whey proteins. This whey compartment ws further characterized by gel electrophoresis, crossed immunoelectrophoresis, ion exchange chromatography and gel filtration chromatography.
|Original language||English (US)|
|State||Published - 1985|
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