Binding of carvedilol to serum albumins investigated by multi-spectroscopic and molecular modeling methods

Carvedilol (CAR) binding to human and bovine serum albumins (HSA and BSA) was studied using fluorescence, UV-vis absorption and Fourier transform infrared spectroscopy (FTIR) and molecular docking techniques at different temperatures (288, 298 and 308 K) under physiologic pH. Results obtained from fluorescence data indicated that values of binding sites (n), effective quenching constants (Ka) and binding constants (K-b) decreased under higher temperature and that the quenching mechanism was static. The thermodynamic parameters including enthalpy (Delta H), entropy (Delta S) and Gibb's free energy (Delta G) changes were calculated by the van't Hoff equation and these data showed that hydrogen bonds and Van der Waals contacts were the main binding force in HSA-CAR and BSA-CAR systems. Binding distance (r) between HSA-CAR and BSA-CAR were calculated by the Forster (fluorescence resonance energy transfer (FRET)) method. FTIR absorption studies showed that the secondary structure was changed according to the interaction of HSA/BSA and CAR. Results determined by molecular docking were in agreement with thermodynamic and FRET data and confirmed that the binding mechanism of Carvedilol to HSA and BSA is different. (C) 2016 Published by Elsevier B.V.