Open AccessThe Composition, Structure and Origin of Proteose‐peptone Component 8F of Bovine Milk
Author(s) -
ANDREWS Anthony T.
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12575.x
Subject(s) - chemistry , chromatography , casein , proteolysis , carboxypeptidase , size exclusion chromatography , hydrolysis , urea , edman degradation , polyacrylamide gel electrophoresis , lysine , composition (language) , peptide , biochemistry , serine , amino acid , peptide sequence , enzyme , linguistics , philosophy , gene
Proteose‐peptone component 8F (or ‘8‐fast’) has been prepared from bovine milk. Sedimentation equilibrium analysis, polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate and gel filtration in urea‐containing buffers all gave molecular weight values between 3300 and 3900. The N‐terminal sequence was found to be Arg‐Glu‐ by dansylation and Edman degradation. Hydrazinolysis released lysine from the C‐terminus. A mixture of carboxypeptidases A and B showed that the C‐terminal sequence was ‐Thr‐(Arg,lle,Asn)‐Lys. The phosphate content was 3.8 mol/mol and was completely released by a short alkaline hydrolysis indicating linkage to serine. This and all other aspects of the composition were entirely consistent with the identification of this proteose‐peptone as residues 1–28 of the β‐casein molecule. This identity was confirmed by a peptide mapping procedure. Thus proteose‐peptone component 8F represents the N‐terminal fragment when the γ 1 ‐caseins are formed by proteolysis of β‐casein.