Department of Chemical Sciences, Indian Institute of Science Education and Research Bhopal, ITI Campus (Gas Rahat) Building, Govindpura, Bhopal 462 023, Madhya Pradesh, India.
Phys Chem Chem Phys. 2012 Mar 28;14(12):4250-8. doi: 10.1039/c2cp00001f. Epub 2012 Feb 21.
The effect of the added fluoroquinolone, Ciprofloxacin Hydrochloride (CpH), on structural properties of Bovine Serum Albumin (BSA) was investigated by Circular Dichroism (CD), steady-state, time-resolved and Dynamic Light Scattering (DLS) spectroscopic approaches. The intrinsic fluorescence of the Tryptophan (Trp) amino acid residue in the globular protein BSA was made use of and the effect of pH at two different temperatures was thoroughly investigated. CD results indicate that CpH induces some structural changes in BSA and this has been well-supported by steady-state, lifetime and DLS data. The fluorescence intensity of Trp gradually decreases with the rise in concentration of CpH and we have conclusively proved that at pH 7.4 and 9.2, the mechanism of fluorescence quenching is mostly dynamic in nature, whereas at pH 4.5 mainly static quenching is operational. Thermodynamic parameters have been studied to rationalize the nature of binding of CpH to BSA, and we have concluded that hydrophobic and van der Waals forces play an important role in the process of drug-protein interaction at three different pH values. The lifetime of Trp was found to decrease with the rise in CpH concentration and the percentage reduction in lifetime was found to be a function of the pH of the medium under investigation.
盐酸环丙沙星（CpH）对牛血清白蛋白（BSA）结构特性的影响，通过圆二色性（CD）、稳态、时间分辨和动态光散射（DLS）光谱方法进行了研究。利用球状蛋白 BSA 中色氨酸（Trp）氨基酸残基的固有荧光，并彻底研究了在两个不同温度下 pH 的影响。CD 结果表明，CpH 诱导 BSA 发生一些结构变化，这得到了稳态、寿命和 DLS 数据的很好支持。随着 CpH 浓度的升高，Trp 的荧光强度逐渐降低，我们已经明确证明，在 pH 7.4 和 9.2 时，荧光猝灭的机制主要是动态的，而在 pH 4.5 时主要是静态猝灭起作用。研究了热力学参数以合理化 CpH 与 BSA 结合的性质，我们得出结论，在三个不同的 pH 值下，疏水作用和范德华力在药物-蛋白质相互作用过程中起重要作用。发现 Trp 的寿命随 CpH 浓度的升高而降低，并且寿命的降低百分比被发现是研究中介质 pH 的函数。
