School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, P. R. China.
Langmuir. 2022 May 17;38(19):6191-6200. doi: 10.1021/acs.langmuir.2c00614. Epub 2022 May 4.
Hydrophobins, a new class of potential protein emulsifiers, have been extensively employed in the food, pharmaceutical, and chemical industries. However, the knowledge of the underlying molecular mechanism of protein adsorption at the oil-water interface remains elusive. In this study, all-atom molecular dynamics simulations were performed to probe the adsorption orientation and conformation change of class II hydrophobin HFBI at the cyclohexane-water interface. It was proposed that a hydrophobic dipole of the protein could be used to quantitatively predict the orientation of the adsorbed HFBI. Simulation results revealed that HFBI adsorbed at the interface with the patch-up orientation toward the oil phase, regardless of its initial orientations. HFBI's secondary structure was maintained to be intact in the course of simulations despite relatively significant variations in the tertiary structure observed, which could well preserve the bioactivity of HFBI. From the energy analysis, the driving force for interface adsorption was primarily determined by van der Waals interactions between HFBI and cyclohexane. Further analysis indicated that the adsorption orientation and conformation of HFBI at the oil-water interface were typically regulated by the hydrophobic patch and some key residues. This study provides some insights into the orientation, conformation, and adsorption mechanism of proteins at the oil-water interface and theoretical guidelines for the design and development of novel biological emulsifiers involved in the food, pharmaceutical, and chemical industries.
水蛋白是一类新型的潜在蛋白质乳化剂，已广泛应用于食品、制药和化工等行业。然而，对于蛋白质在油水界面上吸附的底层分子机制的认识仍然难以捉摸。在这项研究中，我们进行了全原子分子动力学模拟，以探究 II 类水蛋白 HFBI 在环己烷-水界面上的吸附取向和构象变化。我们提出，蛋白质的疏水偶极矩可以用来定量预测吸附 HFBI 的取向。模拟结果表明，HFBI 以面向油相的补丁向上的取向吸附在界面上，无论其初始取向如何。HFBI 的二级结构在模拟过程中保持完整，尽管观察到三级结构发生了相当大的变化，这可以很好地保持 HFBI 的生物活性。从能量分析来看，界面吸附的驱动力主要取决于 HFBI 和环己烷之间的范德华相互作用。进一步的分析表明，HFBI 在油水界面上的吸附取向和构象通常受疏水斑和一些关键残基的调节。这项研究为蛋白质在油水界面上的取向、构象和吸附机制提供了一些见解，并为食品、制药和化工等行业中涉及的新型生物乳化剂的设计和开发提供了理论指导。
