Molecular Biophysics Laboratory, Department of Physics, University of Calabria, 87036 Rende, Italy.
CNR-NANOTEC, Licryl-UOS Cosenza and CEMIF.Cal, Department of Physics, University of Calabria, 87036 Rende, Italy.
Eur J Pharm Sci. 2018 Jan 15;112:122-131. doi: 10.1016/j.ejps.2017.11.013. Epub 2017 Nov 20.
Ibuprofen is one of the most used anti-inflammatory drugs, and it is transported in the blood by human serum albumin, a major plasmatic protein with a peculiar adaptability in the binding of several different ligands. We have characterized the interaction between albumin and ibuprofen, either in racemic mixture, or in the S(+) and R(-) enantiomeric forms, by using differential scanning calorimetry, attenuated total reflectance Fourier transform infrared spectroscopy, and molecular dynamics simulation. The results show that increasing concentrations of ibuprofen (up to sixfold drug/protein molar ratio) improve the protein resistance to thermal unfolding without altering the secondary structure. Deconvolution of the calorimetric thermal profiles at different albumin/ibuprofen molar ratios demonstrates a selective stability of the protein domains where the binding sites of the drug are localized. At the highest ibuprofen concentration, the melting temperature increased by about 10°C with respect to the drug-free protein, whereas the unfolding enthalpy maintains an almost constant value. Furthermore, the degree of protein stabilization depends upon the chirality of the drug, and the R(-) enantiomer is more effective compared to the S(+) form. The stability is supported by molecular dynamics simulations, showing that ibuprofen maintains a stable coordination in the most favorable binding sites, leading to a more compact protein structure at high temperature. The overall results attest that the binding of ibuprofen determines on albumin a stereoselective and domain-specific stabilization with a predominantly entropic character, contributing to clarify significant aspects of the molecular mechanism of protein/drug interaction.
布洛芬是最常用的抗炎药之一，它通过人血清白蛋白在血液中运输，人血清白蛋白是一种主要的血浆蛋白，在与几种不同配体结合方面具有特殊的适应性。我们通过差示扫描量热法、衰减全反射傅里叶变换红外光谱和分子动力学模拟，对白蛋白与布洛芬的相互作用进行了研究，无论是在外消旋混合物中，还是在 S(+)和 R(-)对映异构体形式中。结果表明，布洛芬浓度的增加（高达药物/蛋白摩尔比的六倍）可以提高蛋白对热变性的抵抗力，而不改变二级结构。在不同的白蛋白/布洛芬摩尔比下对量热热谱进行解卷积表明，药物结合位点定位的蛋白结构域具有选择性稳定性。在最高的布洛芬浓度下，与无药物的蛋白相比，蛋白的熔点升高了约 10°C，而展开焓保持几乎恒定的值。此外，蛋白的稳定性取决于药物的手性，R(-)对映体比 S(+)形式更有效。分子动力学模拟支持了这种稳定性，表明布洛芬在最有利的结合位点保持稳定的配位，导致高温下蛋白结构更紧凑。总的来说，这些结果证明，布洛芬与白蛋白的结合决定了白蛋白的立体选择性和特定结构域的稳定性，主要是熵驱动的，有助于阐明蛋白/药物相互作用的分子机制的重要方面。
