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 -casein amino acid sequence, while component 8-fast (PP8F) corresponds to residues 1-28 of β-casein. Thus, these proteose-peptones represent the N-terminal portions of the β-casein molecule, produced by proteolytic cleavages which form the y1-, y2- and y3-caseins from the C-terminal part. The continuing formation of the total proteose-peptone fraction, PP5, PP8F and the γ-caseins during storage of raw milk at 18 or 37 C has also been demonstrated. © 1979, Proprietors of Journal of Dairy Research. All rights reserved.
