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Proteolysis of caseins and the proteose-peptone fraction of bovine milk

Published online by Cambridge University Press:  01 June 2009

Anthony T. Andrews
National Institute for Research in Dairying, Shinfield, Reading RG2 9AT, UK
Efstathios Alichanidis
National Institute for Research in Dairying, Shinfield, Reading RG2 9AT, UK


The proteolysis of highly purified samples of αs1-, αs2-, β-and κ-caseins by porcine plasmin and by bovine plasminogen with urokinase has been examined principally by gel electrophoresis. The resulting peptide band patterns were compared with those of total proteose-peptone (TPP) samples prepared from fresh and stored raw and pasteurized milk, and also with those obtained during the natural course of proteolysis by indigenous enzymes in milk during storage. TPP was found to contain at least 38 components detectable by a single electrophoresis run. Apart from residual traces of whey proteins and intact caseins nearly all of these components were fragments of caseins produced by indigenous plasmin, with products from the breakdown of αs1- and β-casein predominating. Over 90 % of TPP has been accounted for in this way. A fragment consisting of residues 29–105 of β-casein was isolated and characterized from both stored milk and from plasmin digests of β-casein. This fragment was a relatively major product of the natural proteolysis occurring during storage of milk, but contrary to a report in the literature it was not the same as proteose-peptone component 8-slow. Since many of the components of TPP resulted from proteolysis, the composition of TPP was found to vary according to the time and temperature of storage of the milk from which it was prepared. Thus, while the proteose-peptone fraction of milk can easily be defined operationally it cannot be rigorously defined in terms of its composition unless the history of the milk is also defined.

Original Articles
Copyright © Proprietors of Journal of Dairy Research 1983

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Andrews, A. T. 1978 a The composition, structure and origin of proteose-peptone component 5 of bovine milk. European Journal of Biochemistry 90 5965.CrossRefGoogle ScholarPubMed
Andrews, A. T. 1978 b The composition, structure and origin of proteose-peptone component 8F of bovine milk. European Journal of Biochemistry 90 6771.Google Scholar
Andrews, A. T. 1979 The formation and structure of some proteose-peptone components. Journal of Dairy Research 46 215218.CrossRefGoogle ScholarPubMed
Andrews, A. T. 1983 a Proteinases in normal bovine milk and their action on caseins. Journal of Dairy Research 50 4555.CrossRefGoogle ScholarPubMed
Andrews, A. T. 1983 b Breakdown of caseins by proteinases in bovine milks with high somatic cell counts arising from mastitis or infusion with bacterial endotoxin. Journal of Dairy Research 50 5766CrossRefGoogle ScholarPubMed
Davies, H. M. & Miflin, B. J. 1978 Advantages of o-phthalaldehyde for visualising 14C-labelled amino acids on thin layer chromatograms and an improved method for their recovery. Journal of Chromatography 153 284286.Google Scholar
de Rham, O. & Andrews, A. T. 1982 a The roles of native milk proteinase and its zymogen during proteolysis in normal bovine milk. Journal of Dairy Research 49 577585.CrossRefGoogle ScholarPubMed
de Rham, O. & Andrews, A. T. 1982 b Qualitative and quantitative determination of proteolysis in mastitic milks. Journal of Dairy Research 49 587596.CrossRefGoogle ScholarPubMed
Eigel, W. N. 1977 Effect of bovine plasmin on αs1,-B and κ-A caseins. Journal of Dairy Science 60 13991403.Google Scholar
Eigel, W. N., Hofmann, C. J., Chibber, B. A. K., Tomich, J. M., Keenan, T. W. & Mertz, E. T. 1979 Plasmin-mediated proteolysis of casein in bovine milk. Proceedings of the National Academy of Sciences of the United States of America 76 22442248CrossRefGoogle ScholarPubMed
Eigel, W. N. & Keenan, T. W. 1979 Identification of proteose-peptonecomponent 8-slowaaaplasmin-derived fragment of bovine β-casein. International Journal of Biochemistry 10 529535.CrossRefGoogle ScholarPubMed
Gordon, W. G. & Groves, M. L. 1975 Primary sequence of beta, gamma and minor caseins. Journal of Dairy Science 58 574582.CrossRefGoogle Scholar
Gracy, R. W. 1977 Two-dimensional thin-layer methods. Methods in Enzymology 47 195204.CrossRefGoogle ScholarPubMed
Kaminogawa, S., Mizobuchi, H. & Yamauchi, K. 1972 Comparison of bovine milk protease with plasmin. Agricultural and Biological Chemistry 36 21632167.CrossRefGoogle Scholar
Kolar, C. W. & Brunner, J. R. 1970 Proteose-peptone fraction of bovine milk: lacteal serum components 5 and 8-casein associated glycoproteins. Journal of Dairy Science 53 9971008.CrossRefGoogle ScholarPubMed
Laemmli, U. K. 1970 Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227 680685.CrossRefGoogle ScholarPubMed
Larson, B. L. & Rolleri, G. D. 1955. Heat denaturation of the specific serum proteins in milk. Journal of Dairy Science 38 351360.Google Scholar
Ribadeau-Dumas, B., Brignon, G., Grosclaude, F. & Mercier, J-C. 1972 [Primary structure of bovine β-casein]. European Journal of Biochemistry 25 505514.CrossRefGoogle ScholarPubMed
Snoeren, T. H. M. & van Riel, J. A. M. 1979 Milk proteinase, its isolation and action on αs2- and β-casein. Milchwissenschaft 34 528531Google Scholar
Swank, R. T. & Munkres, K. D. 1971 Molecular weight analysis of oligopeptides by electrophoresis in polyacrylamide gel with sodium dodecyl sulphate. Analytical Biochemistry 39 462477.CrossRefGoogle Scholar
Thompson, M. P. 1966 DEAE-cellulose-urea chromatography of casein in the presence of 2-mercaptoethanol. Journal of Dairy Science 49 792795CrossRefGoogle ScholarPubMed