Proteomic analysis of temperature-dependent changes in stored UHT milk

Holland, John W., Gupta, Rajesh, Deeth, Hilton C. and Alewood, Paul F. (2011) Proteomic analysis of temperature-dependent changes in stored UHT milk. Journal of Agricultural and Food Chemistry, 59 5: 1837-1846. doi:10.1021/jf104395v


Author Holland, John W.
Gupta, Rajesh
Deeth, Hilton C.
Alewood, Paul F.
Title Proteomic analysis of temperature-dependent changes in stored UHT milk
Journal name Journal of Agricultural and Food Chemistry   Check publisher's open access policy
ISSN 0021-8561
1520-5118
Publication date 2011-03
Year available 2011
Sub-type Article (original research)
DOI 10.1021/jf104395v
Volume 59
Issue 5
Start page 1837
End page 1846
Total pages 10
Place of publication Washington DC, United States
Publisher American Chemical Society
Collection year 2012
Language eng
Formatted abstract
Molecular changes in milk proteins during storage of UHT-treated milk have been investigated using two-dimensional electrophoresis (2-DE) coupled to MALDI-TOF mass spectrometry. UHT-treated samples were stored at three different temperatures, 4 °C, 28 °C, and 40 °C, for two months. Three main changes could be observed on 2-DE gels following storage. They were (1) the appearance of diffuse staining regions above the position of the monomeric caseins caused by nondisulfide cross-linking of α and β-caseins; (2) the appearance of additional acidic forms of proteins, predominantly of αS1-casein, caused by deamidation; and (3) the appearance of “stacked spots” caused by lactosylation of whey proteins. The extent of the changes increased with increased storage temperature. Mass spectrometric analysis of in-gel tryptic digests showed that the cross-linked proteins were dominated by αS1-casein, but a heterogeneous population of cross-linked forms with αS2-casein and β-casein was also observed. Tandem MS analysis was used to confirm deamidation of N129 in αS1-casein. MS analysis of the stacked spots revealed lactosylation of 9/15 lysines in β-lactoglobulin and 8/12 lysines in α-lactalbumin. More extensive analysis will be required to confirm the nature of the cross-links and additional deamidation sites in αS1-casein as the highly phosphorylated nature of the caseins makes them challenging prospects for MS analysis.
Keyword Two-dimensional electrophoresis
Cross-linking
Deamidation
Lactosylation
Casein
Whey
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Publication Date (Web): February 15, 2011

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
School of Agriculture and Food Sciences
Institute for Molecular Bioscience - Publications
 
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Created: Sun, 20 Mar 2011, 00:11:08 EST