Influence of moderate electric fields in β-lactoglobulin thermal unfolding and interactions

Supplementary data to this article can be found online at https:// doi.org/10.1016/j.foodchem.2019.125442.In this study, the effects of moderate electric fields during thermal denaturation of -lactoglobulin were examined through an in situ circular dichroism approach, complemented by intrinsic extrinsic fluorescence analysis. Results have shown that the effects of electric fields in protein unfolding were linearly dependent on the applied electric field intensity (V/cm) and increased by the use of low electric frequencies i.e. 50 to 200Hz. These electric effects caused significant changes on -lactoglobulin melting temperature, unfolded conformation and subsequent intermolecular interactions, revealed by the increase of surface hydrophobicity (ANS affinity) and higher conservation of retinol binding. The obtained data provides a clear evidence that moderate electric fields contribute to distinct folding/unfolding of -lactoglobulin, resulting in structural modifications. These findings are relevant for (bio)-technological applications involving electric fields processing, bringing new insights for the development of innovative strategies to control protein function and tune production of functional protein systems.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020, Programa Operacional Regional do Norte.Rui M.Rodrigues and Ricardo N. Pereira gratefully acknowledge FCT for their financial grants with references SFRH/BD/110723/2015 and SFRH/BPD/ 81887/2011, respectively. The authors would also like to acknowledge Pedro Silva for his contribution to this work.