Protein conformational changes at the oil/water-interface induced by premix membrane emulsification.

Tobias Wollborn, Monika Michaelis, Lucio Colombi Ciacchi, Udo Fritsching

Journal: Journal of colloid and interface science 2022;628(Pt A):72-81

PMID: 35908433

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Abstract

We present combined experimental and modelling evidence that β-lactoglobulin proteins employed as stabilizers of oil/water emulsions undergo minor but significant conformational changes during premix membrane emulsification processes. Circular Dichroism spectroscopy and Molecular Dynamics simulations reveal that the native protein structure is preserved as a metastable state after adsorption at stress-free oil/water interfaces. However, the shear stress applied to the oil droplets during their fragmentation in narrow membrane pores causes a transition into a more stable, partially unfolded interfacial state. The protein's β-sheet content is reduced by up to 8% in a way that is largely independent of the pressure applied during emulsification, and is driven by an increase of contacts between the oil and hydrophobic residues at the expense of structural order within the protein core.

Address: Leibniz Institute for Materials Engineering - IWT, Badgasteiner Straße 3, 28359 Bremen, Germany. Electronic address: [email protected].; Hybrid Materials Interfaces Group, University of Bremen, Faculty of Production Engineering, Bremen Center for Computational Materials Science, Center for Environmental Research and Sustainable Technology (UFT), Am Fallturm 1, 28359 Bremen, Germany; Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom.; Hybrid Materials Interfaces Group, University of Bremen, Faculty of Production Engineering, Bremen Center for Computational Materials Science, Center for Environmental Research and Sustainable Technology (UFT), Am Fallturm 1, 28359 Bremen, Germany; MAPEX Center for Materials and Processes, Am Fallturm 1, 28359 Bremen, Germany.; Leibniz Institute for Materials Engineering - IWT, Badgasteiner Straße 3, 28359 Bremen, Germany; MAPEX Center for Materials and Processes, Am Fallturm 1, 28359 Bremen, Germany; Particles and Process Engineering, University of Bremen, Badgasteiner Straße 3, 28359 Bremen, Germany.

DOI: 10.1016/j.jcis.2022.07.132

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MeSH Terms: Adsorption, Emulsions, Hydrophobic and Hydrophilic Interactions, Lactoglobulins, Molecular Dynamics Simulation