Title
Binding interaction of ramipril with bovine serum albumin (BSA): Insights from multi-spectroscopy and molecular docking methods
Author
Jie-hua Shi, Dong-qi Pan, Min Jiang, Ting-Ting Liu, Qi Wang
Year
2016
Journal
Journal of Photochemistry and Photobiology B: Biology
Abstract
The binding interaction between a typical angiotensin-converting enzyme inhibitor (ACEI), ramipril, and a transport protein, bovine serum albumin (BSA), was studied in vitro using UV–vis absorption spectroscopy, steady-state fluorescence spectroscopic titration, synchronous fluorescence spectroscopy, three dimensional fluorescence spectroscopy, circular dichroism and molecular docking under the imitated physiological conditions (pH = 7.4). The experimental results suggested that the intrinsic fluorescence of BSA was quenched by ramipril thought a static quenching mechanism, indicating that the stable ramipril–BSA complex was formed by the intermolecular interaction. The number of binding sites (n) and binding constant of ramipril–BSA complex were about 1 and 3.50 × 104 M− 1 at 298 K, respectively, suggesting that there was stronger binding interaction of ramipril with BSA. The thermodynamic parameters together with molecular docking study revealed that both van der Waal's forces and hydrogen bonding interaction dominated the formation of the ramipril–BSA complex and the binding interaction of BSA with ramipril is enthalpy-driven processes due to | ΔH°| > | TΔS°| and ΔG° < 0. The spatial distance between ramipril and BSA was calculated to be 3.56 nm based on Förster's non-radiative energy transfer theory. The results of the competitive displacement experiments and molecular docking confirmed that ramipril inserted into the subdomain IIA (site I) of BSA, resulting in a slight change in the conformation of BSA but BSA still retained its secondary structure α-helicity.
Instrument
J-815
Keywords
Circular dichroism, Secondary structure, Ligand binding, Biochemistry