Molecular Biophysics and Biophysical Chemistry Group, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002, India.
Department of Biosciences, Integral University, Lucknow, 226026, India.
Int J Biol Macromol. 2018 Feb;107(Pt B):2450-2464. doi: 10.1016/j.ijbiomac.2017.10.136. Epub 2017 Nov 2.
Numerous phenolic compounds have been reported in the last decade that have a good antioxidant property and interaction affinity towards mammalian serum albumins. In the present study, we have utilized mammalian serum albumins as a model protein to examine their comparative interaction property with polyphenolic compound tannic acid (TA) by using various spectroscopic and calorimetric methods We have also monitored the esterase and antioxidant activity of mammalian serum albumins in the absence and presence of TA. The obtain results recommended that the TA have a good binding affinity (∼10 to 10M) towards mammalian serum albumins and shows double sequential binding sites, which depends on the concentration of TA that induced the conformational alteration which responsible for the thermal stability of proteins. Binding affinity, structural transition and thermodynamic parameters were calculated from spectroscopic and calorimetric method reveals that non-covalent interaction causes partial conformational alteration in the secondary structure of protein ie.; increase in α-helical content with decrease in β-sheet, random coil and other structure. Meanwhile, we have found that esterase activities of serum albumins were also stabilized against hydrolysis and shows higher antioxidant activity in the presence of TA because albumins its self have an immense antioxidant activity beside TA.
在过去的十年中，已经报道了许多具有良好抗氧化性质和与哺乳动物血清白蛋白相互作用亲和力的酚类化合物。在本研究中，我们利用哺乳动物血清白蛋白作为模型蛋白，通过各种光谱和量热法研究了它们与多酚化合物单宁酸（TA）的比较相互作用特性。我们还监测了 TA 存在和不存在时哺乳动物血清白蛋白的酯酶和抗氧化活性。研究结果表明，TA 与哺乳动物血清白蛋白具有良好的结合亲和力（∼10 到 10M），并显示出双顺序结合位点，这取决于 TA 的浓度，诱导构象改变，这是蛋白质热稳定性的原因。从光谱和量热法计算的结合亲和力、结构转变和热力学参数表明，非共价相互作用导致蛋白质二级结构的部分构象改变，即α-螺旋含量增加，β-折叠、无规卷曲和其他结构减少。同时，我们发现血清白蛋白的酯酶活性也得到了稳定，防止了水解，并在 TA 的存在下表现出更高的抗氧化活性，因为白蛋白本身除了 TA 之外还具有巨大的抗氧化活性。
