Spectroscopic and molecular docking studies on the interaction between N-acetyl cysteine and bovine serum albumin

The interaction between N-acetyl cysteine (NAC) and bovine serum albumin (BSA) was investigated by UV-vis, fluorescence spectroscopy, and molecular docking methods. Fluorescence study at three different temperatures indicated that the fluorescence intensity of BSA was reduced upon the addition of NAC by the static quenching mechanism. Binding constant (K-b) and the number of binding sites (n) were determined. The binding constant for the interaction of NAC and BSA was in the order of 10(3) M-1, and the number of binding sites was obtained to be equal to 1. Enthalpy (H), entropy (S), and Gibb's free energy (G) as thermodynamic values were also achieved by van't Hoff equation. Hydrogen bonding and van der Waals force were the major intermolecular forces in the interaction process and it was spontaneous. Finally, the binding mode and the binding sites were clarified using molecular docking which were in good agreement with the results of spectroscopy experiments. (c) 2015 Wiley Periodicals, Inc. Biopolymers 103: 638-645, 2015.