Kaumbekova Samal, Sugita Masatake, Sakaguchi Naoya, Takahashi Yuta, Sadakane Akira, Umezawa Masakazu
Department of Medical and Robotic Engineering Design, Faculty of Advanced Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo 125-8585, Japan.
Department of Computer Science, School of Computing, Institute of Science Tokyo, Tokyo 152-8552, Japan.
ACS Omega. 2024 Nov 21;9(48):47680-47689. doi: 10.1021/acsomega.4c07274. eCollection 2024 Dec 3.
The use of organic solvents in drug delivery systems (DDSs) either to produce albumin nanoparticles or to manipulate the binding of target molecules to albumin, a promising nanocarrier material, presents challenges due to the conformational changes induced in the protein. In this study, we investigated the alterations in the conformation of bovine serum albumin (BSA) caused by acetonitrile (ACN) in aqueous solution by using a combination of spectroscopic analysis and molecular dynamics (MD) simulations. Ultraviolet (UV) absorption, fluorescence, and infrared (IR) absorption spectroscopy were used to analyze the BSA conformation in the solutions containing 0-60 vol % ACN. Additionally, MD simulations were conducted to elucidate the interactions between BSA and solvent components, focusing on the structural changes in the hydrophobic pocket with Trp residues of the albumin. Increasing the ACN concentration leads to significant changes in the BSA conformation, as evidenced by shifts in UV fluorescence wavelength, decreased intensity, and alterations in IR absorption bands. Furthermore, the formation of protein aggregates was observed at high ACN concentration (30 vol % ACN), shown by increased hydrodynamic diameter distribution. MD simulations further demonstrate that the presence of ACN molecules near the hydrophobic pocket with the Trp-213 residue increases the fluctuations in the positions of amino acids observed near the hydrophobic pocket with Trp-213. Moreover, the intrusion of water molecules into the hydrophobic pocket under 60% ACN conditions with highly decreased solvent polarity was correlated with the changes in the BSA secondary structure. These findings enhance our understanding of how solvent polarity affects the albumin conformation, which is crucial for optimizing albumin-based DDS applications.
在药物递送系统（DDSs）中使用有机溶剂来制备白蛋白纳米颗粒或操控目标分子与白蛋白（一种很有前景的纳米载体材料）的结合，由于蛋白质中诱导的构象变化而带来了挑战。在本研究中，我们通过结合光谱分析和分子动力学（MD）模拟，研究了乙腈（ACN）在水溶液中引起的牛血清白蛋白（BSA）构象变化。利用紫外（UV）吸收、荧光和红外（IR）吸收光谱来分析含有0 - 60体积% ACN的溶液中的BSA构象。此外，进行MD模拟以阐明BSA与溶剂成分之间的相互作用，重点关注白蛋白中含有色氨酸残基的疏水口袋的结构变化。ACN浓度的增加导致BSA构象发生显著变化，这通过UV荧光波长的偏移、强度降低以及IR吸收带的改变得以证明。此外，在高ACN浓度（30体积% ACN）下观察到了蛋白质聚集体的形成，这通过流体动力学直径分布的增加得以体现。MD模拟进一步表明，在含有Trp - 213残基的疏水口袋附近存在ACN分子会增加在含有Trp - 213的疏水口袋附近观察到的氨基酸位置的波动。此外，在溶剂极性大幅降低的60% ACN条件下，水分子侵入疏水口袋与BSA二级结构的变化相关。这些发现增进了我们对溶剂极性如何影响白蛋白构象的理解，这对于优化基于白蛋白的DDS应用至关重要。
