Hostname: page-component-7bb8b95d7b-dtkg6 Total loading time: 0 Render date: 2024-09-26T10:59:22.081Z Has data issue: false hasContentIssue false
  • English
  • Français

A study of the properties of dissociated bovine casein micelles

Published online by Cambridge University Press:  01 June 2009

L. K. Creamer  and
Gillian P. Berry
L. K. Creamer
Affiliation:
New Zealand Dairy Research Institute, Private Bag, Palmerston North, New Zealand
Gillian P. Berry
Affiliation:
New Zealand Dairy Research Institute, Private Bag, Palmerston North, New Zealand
Get access Rights & Permissions [Opens in a new window]

Summary

Although casein micelles are disrupted by removal of Ca, individual caseins remain aggregated in sub-micellar casein aggregates or sub-units. These sub-units have been studied by: (1) the use of gel filtration on Sepharose 4B at 6, 20 and 37°C at pH 6·7 and 0·1 ionic strength, (2) ultracentrifugation and (3) electron microscopy. At 37°C the protein composition of the sub-units varied across the gel-filtration peak, with κ-casein being eluted towards the leading edge and the ratio of αs1- to β-casein being almost constant across the peak. Re-chromatography of the protein from the leading edge of this peak gave a new wide peak with the κ-casein again being eluted towards the leading edge. However, αs1-casein was eluted before β-casein in the leading edge of the new peak. Prior treatment of the casein micelles by dispersion with 6 m-urea solution, precipitation with acid or reduction with 2-mercaptoethanol did not alter the gel-filtration pattern. An examination of the purified casein components and their mixtures showed that a 1:1 ratio mixture of αs1- and β-casein had the same peak maximum elution volume as casein micelle sub-units. κ-Casein by itself eluted at the void volume of the gel-filtration column, but after admixture with a sample of small micelles it eluted at the leading edge of the sub-unit peak and was indistinguishable from the κ-casein normally present. These results suggest that the sub-units are in equilibrium with their component caseins and that their size distribution is determined by only those factors (such as protein concentration, pH, temperature and ionic strength) which determine the strength of association between the casein components. The results from electron microscopy and ultracentrifugation support these conclusions.

Type
Research Article
Information
Journal of Dairy Research , Volume 42 , Issue 1 , February 1975 , pp. 169 - 183
Copyright
Copyright © Proprietors of Journal of Dairy Research 1975

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Buchheim, W. & Welsch, U. (1973). Netherlands Milk and Dairy Journal 27, 163.Google Scholar
Chen, P. S. Jr, Toribara, T. Y. & Warner, H. (1956). Analytical Chemistry 28, 1756.CrossRefGoogle Scholar
Creamer, L. K. (1970). New Zealand Journal of Dairy Science and Technology 5, 152.Google Scholar
Creamer, L. K. (1972). Biochimica et Biophysica Acta 271, 252.CrossRefGoogle Scholar
Downey, W. K. (1973). Netherlands Milk and Dairy Journal 27, 218.Google Scholar
Downey, W. K. & Murphy, R. F. (1970). Journal of Dairy Research 37, 361.CrossRefGoogle Scholar
Ho, C. & Waugh, D. F. (1965). Journal of the American Chemical Society 87, 110.CrossRefGoogle Scholar
Kaminogawa, S., Mizobuchi, H. & Yamauchi, K. (1972). Agricultural and Biological Chemistry 36, 2163.CrossRefGoogle Scholar
Lawrence, R. C. & Creamer, L. K. (1969). Journal of Dairy Research 36, 11.CrossRefGoogle Scholar
Mocquot, G. & Garnier, J. (1965). Journal of Agricultural and Food Chemistry 13, 414.CrossRefGoogle Scholar
Morr, C. V. (1967). Journal of Dairy Science 50, 1744.CrossRefGoogle Scholar
Morr, C. V., Josephson, R. V., Jenness, R. & Manning, P. B. (1971). Journal of Dairy Science 54, 1555.CrossRefGoogle Scholar
Noble, R. W. Jr & Waugh, D. F. (1965). Journal of the American Chemical Society 87, 2236.CrossRefGoogle Scholar
Payens, T. A. J. (1966). Journal of Dairy Science 49, 1317.CrossRefGoogle Scholar
Payens, T. A. J. (1968). Biochemical Journal 108, 14P.Google Scholar
Payens, T. A. J. & Nijhuis, H. (1974). Biochimica et Biophysica Acta 336, 201.CrossRefGoogle Scholar
Payens, T. A. J. & Schmidt, D. G. (1965). Biochimica et Biophysica Acta 109, 214.CrossRefGoogle Scholar
Payens, T. A. J. & Van Markwijk, B. W. (1963). Biochimica et Biophysica Acta 71, 517.CrossRefGoogle Scholar
Pepper, L. (1972). Biochimica et Biophysica Acta 278, 147.CrossRefGoogle Scholar
Rose, D. (1965). Journal of Dairy Science 48, 139.CrossRefGoogle Scholar
Schmidt, D. G. (1969). Nederlands Instituut voor Zuivelonderzoek Verslagen No. 117.Google Scholar
Schmidt, D. G. & Buchheim, W. (1970). Milchwissenschaft 25, 596.Google Scholar
Shimmin, P. D. & Hill, R. D. (1964). Journal of Dairy Research 31, 121.CrossRefGoogle Scholar
Shimmin, P. D. & Hill, R. D. (1965). Australian Journal of Dairy Technology 20, 119.Google Scholar
Slattery, C. W. & Evard, R. (1973). Biochimica et Biophysica Acta 317, 529.CrossRefGoogle Scholar
Sullivan, R. A., Fitzpatrick, M. M., Stanton, E. K., Annino, R., Kissel, G. & Palermiti, F. (1955). Archives of Biochemistry and Biophysics 55, 455.CrossRefGoogle Scholar
von Hippel, P. H. & Waugh, D. F. (1955). Journal of the American Chemical Society 77, 4311.CrossRefGoogle Scholar
Waugh, D. F. (1961). Journal of Physical Chemistry 65, 1793.CrossRefGoogle Scholar
Waugh, D. F. (1971). In Milk Proteins, vol. 2, p. 3. (Ed. McKenzie, H. A..) New York: Academic Press.CrossRefGoogle Scholar
Waugh, D. F., Creamer, L. K., Slattery, C. W. & Dresdner, G. W. (1970). Biochemistry 9, 786.CrossRefGoogle Scholar
Waugh, D. F. & Noble, R. W. Jr (1965). Journal of the American Chemical Society 87, 2246.CrossRefGoogle Scholar
Waugh, D. F. & von Hippel, P. H. (1956). Journal of the American Chemical Society 78, 4576.CrossRefGoogle Scholar
Yaguchi, M., Davies, D. T. & Kim, Y. K. (1968). Journal of Dairy Science 51, 473.CrossRefGoogle Scholar