Université Paris-Saclay, Laboratoire Léon-Brillouin, UMR12 CEA-CNRS, CEA-Saclay, Gif-sur-Yvette Cedex, France.
Université Paris-Saclay, Laboratoire Léon-Brillouin, UMR12 CEA-CNRS, CEA-Saclay, Gif-sur-Yvette Cedex, France.
Biophys J. 2022 Jul 5;121(13):2514-2525. doi: 10.1016/j.bpj.2022.06.003. Epub 2022 Jun 2.
High pressure (HP) is a particularly powerful tool to study protein folding/unfolding, revealing subtle structural rearrangements. Bovine β-lactoglobulin (BLG), a protein of interest in food science, exhibits a strong propensity to bind various bioactive molecules. We probed the effects of the binding of biliverdin (BV), a tetrapyrrole linear chromophore, on the stability of BLG under pressure, by combining in situ HP small-angle neutron scattering (SANS) and HP-UV absorption spectroscopy. Although BV induces a slight destabilization of BLG during HP-induced unfolding, a ligand excess strongly prevents BLG oligomerization. Moreover, at SANS resolution, an excess of BV induces the complete recovery of the protein "native" 3D structure after HP removal, despite the presence of the BV covalently bound adduct. Mass spectrometry highlights the crucial role of cysteine residues in the competitive and protective effects of BV during pressure denaturation of BLG through SH/S-S exchange.
高压（HP）是研究蛋白质折叠/展开的一种特别强大的工具，可以揭示微妙的结构重排。牛β-乳球蛋白（BLG）是食品科学中感兴趣的一种蛋白质，具有强烈结合各种生物活性分子的倾向。我们通过结合原位高压小角中子散射（SANS）和高压紫外吸收光谱法，研究了胆红素（BV）结合对 BLG 在压力下稳定性的影响，BV 是一种四吡咯线性发色团。尽管 BV 在 HP 诱导的展开过程中诱导 BLG 轻微失稳，但配体过量强烈阻止 BLG 寡聚化。此外，在 SANS 分辨率下，尽管存在共价结合的 BV 加合物，BV 的过量会在 HP 去除后完全恢复蛋白质的“天然”3D 结构。质谱法强调了半胱氨酸残基在 BLG 在压力变性过程中通过 SH/S-S 交换与 BV 的竞争和保护作用中的关键作用。
