Department of Biology, Faculty of Sciences, Islamic Azad University, Mashhad Branch, Mashhad, Iran.
J Biomol Struct Dyn. 2011 Feb;28(4):483-502. doi: 10.1080/07391102.2011.10508590.
The interaction between lomefloxacin (LMF) and two drug carrier proteins, human serum albumin (HSA) and serum transferrin (TF), were studied and compared by fluorescence quenching, resonance light scattering (RLS), and circular dichroism (CD) spectroscopic along with molecular modeling. Fluorescence data show that LMF has a stronger quenching effect on HSA than on TF. The binding constant and the number of binding sites were calculated as 6.00 x 10(5) M(-1) and 0.77 for HSA, and 4.66 x 10(5) M(-1) and 1.02, for TF, respectively. Also, these binding parameters were calculated by RLS data, as a novel approach and were compared to that obtained from fluorescence. The micro-environment changes of Trp residues were evident in both proteins. The quantitative analysis of the secondary structure in both proteins further confirmed the drug-induced conformational changes. The distance (r) between donors (HSA and TF) and acceptor (LMF) were obtained by fluorescence resonance energy transfer (FRET) theory and found to be 1.83 nm and 1.71 nm for HSA and TF respectively. Moreover, molecular modeling studies suggested the sub-domain IB in HSA and N-lobe in TF as the candidate place for the formation of the binding site of LMF on these proteins.
采用荧光猝灭、共振光散射（RLS）和圆二色性（CD）光谱以及分子模拟的方法，研究并比较了洛美沙星（LMF）与两种药物载体蛋白（人血清白蛋白（HSA）和血清转铁蛋白（TF））之间的相互作用。荧光数据表明，LMF 对 HSA 的猝灭作用强于 TF。通过计算得到，LMF 与 HSA 的结合常数和结合位点数分别为 6.00×10(5) M(-1)和 0.77，与 TF 的分别为 4.66×10(5) M(-1)和 1.02。此外，还通过 RLS 数据计算了这些结合参数，这是一种新方法，并与荧光法得到的结果进行了比较。两种蛋白质中色氨酸残基的微环境变化都很明显。对两种蛋白质中二级结构的定量分析进一步证实了药物诱导的构象变化。通过荧光共振能量转移（FRET）理论计算得到供体（HSA 和 TF）与受体（LMF）之间的距离（r）分别为 1.83nm 和 1.71nm。此外，分子模拟研究表明，HSA 的亚域 IB 和 TF 的 N- lobe 是 LMF 在这些蛋白质上形成结合位点的候选位置。
