Spectroscopic analysis of everolimus and human serum albumin interaction

From the point of conformation, kinetics, and function, human serum albumin (HSA) is an effectively characterized serum protein. Therefore, it has been used broadly in the study of biotechnology and pharmaceutical fields. On the understanding of the protein-drug interactions, it can become the main potential target. The study aims to gain a biophysical sight in the interaction of HSA with Everolimus (Evo), a potent macrolide immunosuppressant agent. Evo has been shown to be effective against various cancers and is used alone or in combination with other drugs to prevent the rejection of organ transplants. Various spectroscopic approaches, including emission, synchronous fluorescence, three-dimensional fluorescence, Fourier transform infrared spectroscopy, UV-visible spectroscopy, circular dichroism, and zeta potential methods, were used in this investigation under physiological settings. Based on the fluorescence quenching process, binding constants (Ka) and binding sites (n) were found using a modified Stern-Volmer analysis at three different temperatures. The thermodynamic parameters of entropy change (ΔS), the enthalpy change (ΔH), and free energy change (ΔG) are calculated using the van't Hoff equation. The Förster theory was used to calculate the binding distance between HSA and Evo. To validate conformational changes in HSA under the impact of Evo, researchers used three-dimensional fluorescence, synchronous fluorescence, Fourier transform infrared spectra, circular dichroism spectroscopy, and ultraviolet-visible absorbance spectroscopy. Moreover, the zeta potential of binding of HSA to Evo was determined in the pH = 7.4. All results are vital to the pharmacodynamic and pharmacokinetic study of Everolimus and its further developments.