Model process for removal of caseins from milk of transgenic animals

We describe a method for selective removal of caseins from milk. The method was developed as a model for transgenic milk processing. Raw cow milk spik ed with nonmilk proteins was chosen as the model to resemble transgenic ani mal milk containing recombinant proteins. The most important elements of th e process are (1) "deconstruction" of casein micelles in milk by destroying their Ca2+ core using a chelating agent (EDTA), thus freeing any protein t hat might be entrapped in casein aggregates, and (2) "reconstruction" of mi celles by providing them with a new Ca2+ core, thus precipitating them away from the whey proteins, and the protein of interest. Calcium phosphate par ticles (CAP) were used to reform the disrupted casein micelles. The crystal clear supernatant fraction generated by this method provided > 90% recover y and 6- to 13-fold concentration of the desired protein. Product-rich supe rnatant contained no detectable casein residues, as silver-stained SDS-PAGE and Western blot analyses demonstrated.