Whey genetic variant

The proteins of milk fall into several classes of polypeptide chains. These have been delineated most completely in bovine milk, and a system of nonmenclature has been developed for them (Chapter 3 Eigel et al. 1984). One group, called caseins, consists of four kinds of polypeptides asr, as2-. and 3-, and k- with some genetic variants, post translational modifications, and products of proteolysis. Almost all of the caseins are associated with calcium and phosphate in micelles 20-300 fim in diameter (see Chapter 9). The other milk proteins, called whey proteins, are a diverse group including /3-lactoglobulin, a-lactalbumin, blood serum albumin, and immunoglobulins (Chapter 3). Almost all... 

Electrophoresis on cellulose acetate strips has also been used for the rapid resolution of whey proteins (Bell and Stone 1979). Samples of a 10 1 concentrate of whey are applied to cellulose acetate strips which have been saturated with Tris-barbiturate buffer, pH 8.6, ionic strength 0.097, and the electrophoresis is performed at 225 V for 1 hr. This procedure separates not only the major whey proteins but also their genetic variants. 

CE, with its high resolving power, rapid method development, easy sample preparation, and low operational cost, is reported to be an excellent technique for resolving caseins (including different genetic variants), peptides derived from them, and whey proteins (16-19). Peptide profiles obtained by CE supplement the information obtained by reversed-phase high performance liquid chromatography (RP-HPLC) (17, 20). The application of CE to the assessment of proteolysis in milk and different cheese types has acquired an enormous importance in recent years. Reviews on the application of CE to this field can be found in papers by Otte et al. (21) and Redo et al. (22). 

Two peaks, corresponding to the aglyco components of the two principal genetic variants (A and B) of CMP, eluted after less-resolved glyco-CMP components. Calibration curves with concentrations ranging from 15 to 200 mg/ml were constructed. The detection limit was 2 mg/ml. Recoveries of 93% and 97% were obtained for concentration levels 0.10 and 0.20 mg/ml, respectively. The RSD was less than 4.87% (n = 10). Thus, the HPLC/UV procedure is suitable for detection of adulteration of powdered milk with rennet whey. 

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