Biophysical Insight into Furosemide Binding to Human Serum Albumin: A Study To Unveil Its Impaired Albumin Binding in Uremia
Biophysical Insight into Furosemide Binding to Human Serum Albumin: A Study To Unveil Its Impaired Albumin Binding in Uremia
复制标题
DOI：
10.1021/jp3069877
复制
发表时间：
2013-03-07
影响因子：
3.3
通讯作者：
Khan, Rizwan H.
中科院分区：
文献类型：
--
作者：
Zaidi, Nida;Ahmad, Ejaz;Khan, Rizwan H.
外源性物质，如药物，当被吸收后进入循环系统，并可逆地广泛结合到人血清白蛋白(HSA)。但由于尿毒症毒素的积累，尿毒症患者通过白蛋白转运的各种药物，如利尿剂速尿(FUR)，会受到严重影响。通过研究毛皮与人血清白蛋白的结合机理，探讨了毛皮与人血清白蛋白结合的原因。等温滴定量热结果表明，毛发与HSA在高(K-b类似于10(4))和低亲和力(K-b类似于10(3))位结合，而光谱结果预测在单个位置(K-b类似于10(5))结合。热力学分析表明，HSA-FUR通过氢键和疏水相互作用形成了HSA-FUR络合物，FTIR和远紫外CD表明，HSA-FUR络合物的结构发生了轻微的变化。此外，HSA的寿命仅略有下降，因此能量转移效率的大小很小，这是通过时间分辨测量获得的。置换实验预测，毛发主要与位点I结合，但也观察到一个亲和力较低的新位点，该位点与分子对接结果支持的位点II共享一些残基。结果表明，在尿毒症中，FUR与结合位点II的尿毒症毒素间接竞争Arg410、Lys414和Ser489，与结合位点I的尿毒症毒素直接竞争结合位点I。
Exogenous substances like drugs, when absorbed, enter into the circulatory system and bind reversibly and extensively to human serum albumin (HSA). But transport of various drugs like a diuretic, furosemide (FUR), via albumin in uremia is seriously compromised due to accumulation of uremic toxins. The reason behind it is explored by investigating the binding mechanism of FUR to HSA. Isothermal titration calorimetry results show that FUR binds with HSA at high (K-b similar to 10(4)) and low affinity (K-b similar to 10(3)) sites whereas spectroscopic results predict binding at a single site (K-b similar to 10(5)). Thermodynamic analysis shows that the HSA-FUR complex formation occurs via hydrogen bonds and hydrophobic interactions and undergoes slight structural changes, as evident by FTIR and far-UV CD. Further, the lifetime of HSA decreases only marginally and thus the magnitude of energy transfer efficiency is small, as obtained by time-resolved measurements. A displacement experiment predicts that the FUR binds mainly to site I but a new site having lower affinity is also observed, which shares some residues with site II as supported by molecular docking results. Results revealed that in uremia, FUR indirectly competes for Arg410, Lys414, and Ser489 with site II bound uremic toxins and directly competes for site I with site I bound uremic toxins.