Abstract

Binding interactions of the phenazinium dye Janus green blue (JGB) with human and bovine serum albumins (HSA and BSA) have been explored for the first time from multi-spectroscopic and calorimetric measurements aided by in silico calculations. The formation of ground state complexes between JGB and the respective serum albumins have been suggested from the UV–Vis and steady-state fluorescence spectroscopic studies. The nonlinear Stern Volmer (SV) plots at higher concentrations of JGB primarily indicate the formation of more than one ground state complexes in HSA/BSA–JGB systems. Modified SV plots and isothermal titration calorimetry (ITC) studies further confirm the above referred conjecture. Binding constants and the thermodynamic parameters associated with the HSA/BSA–JGB complexes have also been estimated from the ITC studies. Förster distances (R₀ ) for HSA–JGB and BSA–JGB complexes are estimated from Förster resonance energy transfer (FRET) results. Variations in the micro-environment of the Tyr and Trp residues of the serum proteins in presence of JGB have been observed from the synchronous fluorescence measurements. The conformational changes in the protein structures induced by the dye JGB have been revealed from 3 D fluorescence and circular dichroism (CD) studies. The experimental observations are supported by in silico calculations. This in depth investigation on the interactions of serum albumins with JGB may provide the fundamental information toward exploring the therapeutic efficacy of JGB as a potent drug molecule.

Communicated by Ramaswamy H. Sarma

摘要

在计算机辅助的多光谱和量热法测量中，首次探索了吩嗪鎓染料Janus绿蓝（JGB）与人和牛血清白蛋白（HSA和BSA）的结合相互作用。计算。紫外可见光谱和稳态荧光光谱研究表明，JGB和各自的血清白蛋白之间形成了基态复合物。JGB浓度较高时的非线性Stern Volmer（SV）图主要表明在HSA / BSA–JGB系统中形成了多个基态复合物。修改后的SV图和等温滴定量热（ITC）研究进一步证实了上述推测。结合常数和与HSA / BSA–JGB复合物相关的热力学参数也已从ITC研究中估算出来。福斯特距离（R ₀ ）对于HSA–JGB和BSA–JGB配合物，根据Förster共振能量转移（FRET）结果进行估算。从同步荧光测量中已经观察到在存在JGB的情况下血清蛋白的Tyr和Trp残基的微环境的变化。由 3D荧光和圆二色性（CD）研究已揭示了染料JGB诱导的蛋白质结构的构象变化。实验观察得到计算机模拟的支持。这项关于血清白蛋白与JGB相互作用的深入研究可为探索JGB作为有效药物分子的治疗功效提供基础信息。

由Ramaswamy H.Sarma沟通