JDS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Journal of Dairy Science Vol. 46 No. 5 373-379
© 1963 by American Dairy Science Association ®
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Marier, J. R.
Right arrow Articles by Rose, D.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Marier, J. R.
Right arrow Articles by Rose, D.

Sialic Acid as an Index of the {kappa}-Casein Content of Bovine Skimmilk1

J. R. Marier, H. Tessier and Dyson Rose

Division of Applied Biology, National Research Council, Ottawa, Canada

ABSTRACT

The sialic acid content of skimmilk proteins has been examined, using a modification of Warren's thiobarbituric acid method. Lactose interferes with this method and was removed by thorough washing of the proteins. {kappa}-casein and proteose-peptone appear to be the only two skimmilk proteins containing significant amounts of sialic acid. Treatments with DEAE cellulose almost completely removed the low concentrations of sialic acid present in {alpha}s- and ß-caseins, and examination of these caseins by starch gel electrophoresis indicates that such removal involved traces of {kappa}-casein.

Since the stability of {alpha}s-{kappa}-casein mixtures in the presence of calcium appeared to be directly related to the sialic acid content of the mixture at all levels below the 0.37% (uncorrected for moisture) needed to give complete stability, it is concluded that sialic acid measurements can be used as an index of the intact {kappa}-casein content of such mixtures.

Proteose-peptone is precipitated by 12% TCA, but remains in solution at pH 4.5, so analysis of sialic acid can also be used as an index of the {kappa}-casein concentration of whole acid casein. Values of 0.26–0.59% sialic acid were obtained in washed whole acid caseins prepared from individual lots of milk, indicating that the proportion of {kappa}-casein is variable. The sialic acid content of {kappa}-casein appears to be close to 2.3%; on this basis, the proportion of {kappa}-casein in whole acid casein varies between 11–26%.

FOOTNOTES

1 Issued as N.R.C. No. 7367.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1963 by the American Dairy Science Association ®.