Chemical Structure Studies of Cow ϰ‐Casein: Study of the soluble tryptic peptides

The sequences of 13 tryptic peptides of cow ϰA‐casein (accounting for about one half of the amino acid residues present in the protein) were established. The rennin sensitive linkage could be located in a large fragment (36 residues). ϰ‐casein consists of a hydrophilic part (ϰ‐caseino‐glycopeptide) and of a hydrophobic moiety (para‐ϰ‐casein); in this latter, however, several quite hydrophilic sequences were characterized. Another feature of the ϰ‐casein structure is the frequent duplication or triplication of certain amino acids (Pro‐Pro; Phe‐Phe; Gln‐Gln‐Gln‐Asn‐Glu‐Glu‐Glu; Pro‐Pro‐Lys‐Lys‐Asn‐Gln‐; etc. …).