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pH- and heat-induced structural changes of bovine α-lactalbumin in response to oleic acid binding

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Abstract

Bovine α-lactalbumin (α-LA) is able to interact with fatty acids, resulting in structural changes that are potentially responsible for the HAMLET/BAMLET role. Different states of α-LA induced by pH, temperature and fatty acid binding have been examined. Evidences of the structural changes of α-LA in molten globule and native states in correlation with oleic acid (OA) binding are shown using fluorescence spectroscopy and in silico approach. In addition, the α-LA was subjected to automated docking analysis, to better understand the interaction with oleic acid, using the PatchDock algorithm. The experimental results demonstrate a more flexible conformation of the protein at pH 2.5 when compared to neutral pH, thus facilitating the oleic acid binding to α-LA. The quenching experiments indicate the remarkable increase in the content of molten globule state at pH 2.5 and a more compact and rigid structure for α-LA–OA complexes at pH 7.0. The docking results are consistent with the experimental data concerning the thermal stability of the α-LA–OA complex. α-LA in different conformations/complexes was sensitive to pH and temperature. Several different molecular species induced by pH, heat treatment and oleic acid binding were suggested. The structure of the protein was more flexible at acidic pH, therefore favoring the hydrophobic exposure.

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Acknowledgments

This work was supported by the 2010 POSDRU/89/1.5/S/52432 project, Organizing the national interest postdoctoral school of applied biotechnologies with impact on Romanian bioeconomy, project co-financed by the European Social Fund through the Sectoral Operational Programme Human Resources Development 2007-2013.

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  1. Food Science, Food Engineering and Applied Biotechnology Department, Faculty of Food Science and Engineering, “Dunarea de Jos” University of Galati, 111 Domneasca Street, Building F, Room 107, 800201, Galati, Romania

    Nicoleta Stănciuc, Iuliana Aprodu, Gabriela Râpeanu & Gabriela Bahrim

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  1. Nicoleta Stănciuc
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  2. Iuliana Aprodu
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  3. Gabriela Râpeanu
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Correspondence to Iuliana Aprodu.

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Stănciuc, N., Aprodu, I., Râpeanu, G. et al. pH- and heat-induced structural changes of bovine α-lactalbumin in response to oleic acid binding. Eur Food Res Technol 236, 257–266 (2013). https://doi.org/10.1007/s00217-012-1882-9

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  • DOI: https://doi.org/10.1007/s00217-012-1882-9

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