The interaction between nitrite ion and bovine serum albumin (BSA), in an aqueous environment, was studied using spectroscopic methods, including fluorescence quenching technique, synchronous fluorescence, UV[BOND]Vis spectrophotometry and Resonance Rayleigh Scattering (RRS), and molecular docking technique. The experimental results showed that nitrite ion effectively quenched the intrinsic fluorescence of BSA with the static quenching. The ion-BSA binding constant was determined to be 3.69×103 L mol−1. As the results showed the stoichiometry of binding nitrite ion to BSA was 1 : 1. Furthermore the thermodynamic parameters and nature of the binding force were calculated. The negative ΔHo and ΔSo values of reaction between nitrite ion and BSA indicated the predominant forces in the ion-BSA interactions are hydrogen bonding interactions. Based on the Förster’s theory of non-radiative energy transfer, the binding distance between nitrite ion and the inner tyrosine and tryptophan residue of BSA were determined to be 2.16 nm. Furthermore binding site of this ion on BSA was carried out by molecular docking technique.
