Structural consequences of dry heating on alpha-lactalbumin and beta-lactoglobulin at pH 6.5

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• 作者：Muhammad Gulzar^a ; ^b ; ^c ; Saï ; d Bouhallab^a ; ^b ; Julien Jardin^a ; ^b ; Valé ; rie Briard-Bion^a ; ^b ; Thomas Croguennec^a ; ^b ; ^{thomas.croguennec@agrocampus-ouest.fr}
• 关键词：Alpha-lactalbumin ; Dry heating ; Dehydration ; Pyroglutamic acid ; Protein cross-linking
• 刊名：Food Research International
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：51
• 期：2
• 页码：899-906
• 全文大小：630 K

文摘

In the present work, we investigated the structural modifications occurring during the dry heating of model whey proteins, ¦Â-lactoglobulin and ¦Á-lactalbumin. Samples were adjusted to pH 6.5, water activity ab>wb> = 0.23 and dry heated at 100 ¡ãC for up to 24 h, and the structural modifications followed by gel permeation chromatography, reverse phase-HPLC, SDS PAGE and mass spectrometry (LC-MS/MS). The dry heating treatment traps a fraction of the proteins into covalently linked soluble aggregates. Moreover, a high proportion of non-aggregated ¦Á-lactalbumin (about 73 % ) was converted into non-native forms. The characteristic of those non-native species was the loss of one or two water molecules per ¦Á-lactalbumin molecules. Using tandem mass spectrometric peptide mapping, these chemical modifications were found to be attributed to (i) the formation of a pyroglutamic acid from the N-terminal glutamic acid and (ii) the formation of an internal cyclic imide at position Aspb>64b>. The non-native species were not favored in the case of ¦Â-lactoglobulin as they represented less than 18 % of non-aggregated proteins.