Investigation on the interaction of the toxicant, gentian violet, with bovine hemoglobin

Gentian violet (GV) is a well-known triarylmethane dye that is used in aquacultural, industrial and medicinal fields. But concerns in growing number have been paid to its potential health problems to human beings and its hazardous effects to environment. Herein, the toxic interaction of GV with bovine hemoglobin (BHb) was investigated by a series of spectroscopic methods and molecular modeling method. The fluorescence emission profile exhibited a remarkable quenching upon addition of GV to the buffered aqueous solution of BHb and the analysis of results revealed the dominant role of static quenching mechanism in GV–BHb interaction. The negative ΔH and positive ΔS values demonstrated that the electrostatic interactions mainly stabilized this toxicantprotein complex. Synchronous fluorescence, UV–Vis absorption and CD spectroscopic studies proved that the conformational change of BHb was induced by GV’s combination. Molecular modeling studies exhibited the binding mode of GV–BHb complex and the detailed information of related driving forces. During the 1H nuclear magnetic resonance spectra (1H NMR) study, the chemical shift perturbation and spin–lattice relaxation times of different protons were further used to investigate the interaction of GV with BHb and the results indicated that GV bound orientationally to BHb.