Kasparek Adam, Smyk Bogdan
Department of Physics and Biophysics, University of Warmia and Mazury in Olsztyn Oczapowskiego 4 10-719 Olsztyn Poland
RSC Adv. 2020 Feb 28;10(15):8810-8820. doi: 10.1039/c9ra09980h. eCollection 2020 Feb 27.
The methyl ester of sinapic acid (MESA) is a molecule with confirmed antioxidant properties. It is important to establish whether it can be transported across humans and animals. Therefore, we investigated MESA interactions with serum albumins, namely, human serum albumin (HSA), bovine serum albumin (BSA), rabbit serum albumin (RSA), and sheep serum albumin (SSA). Experiments were performed in a pH range from 5.9 to 10.7 using absorption and fluorescence techniques. It was found that MESA formed complexes with every albumin in the entire pH range under examination, which was confirmed by the appearances of new absorption and fluorescence complex bands. Fluorescence intensities were much higher (up to 20 times) and lifetimes were up to 340 times as compared to those for unbound MESA. The quenching experiments at pH 7.4 showed that the stoichiometry for every albumin was 1 : 1; the binding constant was the highest for HSA, which reached 52 000 M. The obtained results suggested that MESA preferred the hydrophobic binding sites in albumins. The analysis of the fluorescence spectra and fluorescence lifetimes showed two possibly different binding sites in BSA, RSA, and SSA as well as three binding sites in HSA.
芥子酸甲酯（MESA）是一种具有确定抗氧化特性的分子。确定它是否能够在人和动物体内转运很重要。因此，我们研究了MESA与血清白蛋白的相互作用，即人血清白蛋白（HSA）、牛血清白蛋白（BSA）、兔血清白蛋白（RSA）和羊血清白蛋白（SSA）。使用吸收和荧光技术在pH值为5.9至10.7的范围内进行实验。发现在整个检测的pH范围内，MESA与每种白蛋白都形成了复合物，这通过新的吸收和荧光复合物条带的出现得到了证实。与未结合的MESA相比，荧光强度要高得多（高达20倍），寿命长达340倍。在pH 7.4下的猝灭实验表明，每种白蛋白的化学计量比为1∶1；HSA的结合常数最高，达到52000 M。所得结果表明，MESA优先结合白蛋白中的疏水结合位点。对荧光光谱和荧光寿命的分析表明，BSA、RSA和SSA中可能有两个不同的结合位点，HSA中有三个结合位点。
