Model proteolysis of beta-casein by immobilized trypsin.

The enzymic degradation of beta-casein by immobilized trypsin is described and its use as a model system to study proteolytic reactions which occur in milk during processing is examined. Quantitative determination of proteolysis can be obtained by densitometric transmission measurement of patterns obtained by polyacrylamide-gel electrophoresis. Staining properties of some of the individual components in the electrophoretic patterns were determined by calibration with pure protein and peptide preparations. The isolation of pure beta- and gamma-caseins and the preparation of several forms of immobilized trypsin are outlined.