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Mapping the glycoxidation product N ε ‐carboxymethyllysine in the milk proteome
Author(s) -
Meyer Bianca,
AlDiab Dima,
Vollmer Gregor,
Pischetsrieder Monika
Publication year - 2011
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.201000233
Subject(s) - glycation , chemistry , casein , proteome , posttranslational modification , food science , biochemistry , advanced glycation end product , proteomics , chromatography , beta lactoglobulin , whey protein , milk protein , enzyme , receptor , gene
Milk processing leads to severe protein damage caused by the formation of nonenzymatic posttranslational modifications (nePTMs), such as glycation and glycoxidation. As a result, the technological and nutritional function of milk proteins can be critically altered. The present study investigated the protein‐specific distribution of the glycoxidation product N ε ‐carboxymethyllysine (CML) in the proteome of processed milk. For this purpose, raw milk and heated milk were separated by 1‐D or 2‐DE. The distribution of CML in the milk proteome was examined by immunoblotting. The changes in the protein composition that occurred during heating were monitored by Coomassie staining. Relative modification rates were measured for the major milk protein fractions after 30 and 60 min of heating at 120°C and normalized to the content of the respective protein fraction in the samples. The highest glycoxidation rates were detected in the high molecular weight aggregates that are generated during heating. The casein fraction and the whey protein β‐lactoglobulin were affected in a similar manner. The relevance of the results for industrial milk processing was confirmed by analyzing several commercial milk products accordingly. The presented approach allows nonenzymatic posttranslational modification mapping of the entire milk proteome.