The formation and structure of some proteose-peptone components.

Two constituents of the proteose-peptone fraction of bovine milk have been isolated and characterized. Component 5 (PP5) has been shown to represent residues 1-105 and 1-107 of the beta-casein amino acid sequence, while component 8-fast (PP8F) corresponds to residues 1-28 of beta-casein. Thus, these proteose-peptones represent the N-terminal portions of the beta-casein molecule, produced by proteolytic cleavages which form the gamma 1, gamma 2 and gamma 3-caseins from the C-terminal part. The continuing formation of the total proteose-peptone fraction, PP5, PP8F and the gamma-caseins during storage of raw milk at 18 or 37 degrees C has been also been demonstrated.