School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China.
School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Jan 5;264:120207. doi: 10.1016/j.saa.2021.120207. Epub 2021 Aug 6.
Lysozyme (Lyz) is an important antibacterial protein that exists widely in nature. In recent years, the application of graphene oxide (GO) in the field of biotechnology electronics, optics, chemistry and energy storage has been extensively studied. However, due to the unique properties of GO, the mechanism of its interaction with biomacromolecule proteins is very complex. To further explore the interaction between GO and proteins we explore the influence of different pH and heat treatment conditions on the interaction between GO and Lyz, the GO (0-20 μg/mL) was added at a fixed Lyz concentration (0.143 mg/mL) under different pHs. The structure and surface charge changes of Lyz were measured by spectroscopic analysis and zeta potential. The results showed that the interaction between GO and Lyz depends on temperature and pH, significant changes have taken place in its tertiary and secondary structures. By analyzing the UV absorption spectrum, it was found that lysozyme and GO formed a stable complex, and the conformation of the enzyme was changed. In acidic pH conditions (i.e., pH < pI), a high density of Lyz were found to adsorb on the GO surface, whereas an increase in pH resulted in a progressive decrease in the density of the adsorbed Lyz. This pH-dependent adsorption is ascribed to the electrostatic interactions between the negatively charged GO surface and the tunable ionization of the Lyz molecules. The secondary structure of Lyz adsorbed on GO was also found to be highly dependent on the pH. In this paper, we investigated the exact mechanism of pH-influenced GO binding to lysozyme, which has important guidance significance for the potential toxicity of GO biology and its applications in biomedical fields such as structure-based drug design.
溶菌酶（Lyz）是一种广泛存在于自然界中的重要抗菌蛋白。近年来，氧化石墨烯（GO）在生物技术电子学、光学、化学和储能等领域的应用得到了广泛研究。然而，由于 GO 的独特性质，其与生物大分子蛋白质相互作用的机制非常复杂。为了进一步探讨 GO 与蛋白质的相互作用，我们研究了不同 pH 值和热处理条件对 GO 与 Lyz 相互作用的影响，在不同 pH 值下，将固定浓度的 Lyz（0.143mg/mL）与不同浓度的 GO（0-20μg/mL）混合。通过光谱分析和动电电位测量了 Lyz 的结构和表面电荷变化。结果表明，GO 与 Lyz 的相互作用取决于温度和 pH 值，其三级和二级结构发生了显著变化。通过分析紫外吸收光谱，发现溶菌酶和 GO 形成了稳定的复合物，并且酶的构象发生了变化。在酸性 pH 条件（即 pH<pI）下，发现大量 Lyz 吸附在 GO 表面，而随着 pH 值的增加，吸附的 Lyz 密度逐渐降低。这种 pH 依赖性吸附归因于带负电荷的 GO 表面与 Lyz 分子的可调离子化之间的静电相互作用。在 GO 上吸附的 Lyz 的二级结构也高度依赖于 pH 值。本文研究了 pH 影响 GO 与溶菌酶结合的确切机制，这对 GO 生物学的潜在毒性及其在结构药物设计等生物医学领域的应用具有重要的指导意义。
