Complexes between linoleate and native or aggregated β-lactoglobulin: Interaction parameters and in vitro cytotoxic effect

摘要

The dairy protein b-lactoglobulin (blg) is known to form a complex with fatty acids (FA). Due to industrial processing, blg is often in its non-native form in food products, which can modify the FA/blg complex properties. We investigated the interaction of bovine blg, in selected structural forms (native blg, a covalent dimer and as nanoparticles), with linoleate (C18:2). Using fluorescence and Isothermal Titration Calorimetry, linoleate was found to bind blg at two different binding sites. Regardless of the structural state of blg, association constants remained in the same order of magnitude. However, the stoichiometry increased up to 6-fold for nanoparticles, compared to that of native blg. The impact of these structural changes on linoleate uptake in vitro was measured by cytotoxicity assays on Caco-2 cells. The order of cytotoxicity of linoleate was as follows: free > complexed to dimers > complexed to nanoparticles > complexed to native blg. Therefore, the in vitro cytotoxicity of linoleate could be modulated by altering the state of blg aggregation, which in turn affects its binding capacity to the FA.