Pawar Suma K, Jaldappagari Seetharamappa
Department of Chemistry, Karnatak University, Dharwad, India.
Luminescence. 2017 Sep;32(6):942-951. doi: 10.1002/bio.3275. Epub 2017 Feb 24.
In the present work, the mechanism of the interaction between a β1 receptor blocker, metoprolol succinate (MS) and human serum albumin (HSA) under physiological conditions was investigated by spectroscopic techniques, namely fluorescence, Fourier transform infra-red spectroscopy (FT-IR), fluorescence lifetime decay and circular dichroism (CD) as well as molecular docking and cyclic voltammetric methods. The fluorescence and lifetime decay results indicated that MS quenched the intrinsic intensity of HSA through a static quenching mechanism. The Stern-Volmer quenching constants and binding constants for the MS-HSA system at 293, 298 and 303 K were obtained from the Stern-Volmer plot. Thermodynamic parameters for the interaction of MS with HSA were evaluated; negative values of entropy change (ΔG°) indicated the spontaneity of the MS and HSA interaction. Thermodynamic parameters such as negative ΔH° and positive ΔS° values revealed that hydrogen bonding and hydrophobic forces played a major role in MS-HSA interaction and stabilized the complex. The binding site for MS in HSA was identified by competitive site probe experiments and molecular docking studies. These results indicated that MS was bound to HSA at Sudlow's site I. The efficiency of energy transfer and the distance between the donor (HSA) and acceptor (MS) was calculated based on the theory of Fosters' resonance energy transfer (FRET). Three-dimensional fluorescence spectra and CD results revealed that the binding of MS to HSA resulted in an obvious change in the conformation of HSA. Cyclic voltammograms of the MS-HSA system also confirmed the interaction between MS and HSA. Furthermore, the effects of metal ions on the binding of MS to HSA were also studied.
在本研究中,采用荧光光谱、傅里叶变换红外光谱(FT-IR)、荧光寿命衰减和圆二色光谱(CD)等光谱技术,以及分子对接和循环伏安法,研究了β1受体阻滞剂琥珀酸美托洛尔(MS)与人体血清白蛋白(HSA)在生理条件下的相互作用机制。荧光和寿命衰减结果表明,MS通过静态猝灭机制猝灭了HSA的固有荧光强度。根据Stern-Volmer曲线获得了293、298和303K下MS-HSA体系的Stern-Volmer猝灭常数和结合常数。评估了MS与HSA相互作用的热力学参数;熵变(ΔG°)的负值表明MS与HSA相互作用的自发性。诸如负的ΔH°和正的ΔS°值等热力学参数表明,氢键和疏水作用力在MS-HSA相互作用中起主要作用,并使复合物稳定。通过竞争位点探针实验和分子对接研究确定了MS在HSA中的结合位点。这些结果表明,MS与HSA结合于Sudlow位点I。基于Foster共振能量转移(FRET)理论计算了能量转移效率以及供体(HSA)与受体(MS)之间的距离。三维荧光光谱和CD结果表明,MS与HSA的结合导致HSA构象发生明显变化。MS-HSA体系的循环伏安图也证实了MS与HSA之间的相互作用。此外,还研究了金属离子对MS与HSA结合的影响。