Spectroscopic study on the interaction between [Hg(SCN)4]2− and hemoglobin

The interaction between [Hg(SCN)4]2− and hemoglobin (Hb) under conditions that simulate a physiological environment was investigated by UV–vis spectroscopy, fluorescence spectroscopy, resonance Rayleigh scattering (RRS) spectroscopy and circular dichroism (CD) spectroscopy. The results obtained from the change of UV–vis and CD spectra, the quenching of Hb fluorescence and the enhancement of RRS intensity proved that a 10:1 type complex was formed between [Hg(SCN)4]2− and Hb. The possible mechanism suggested for the interaction was that ten Hg(SCN)4]2− anions entered the four subunits of a Hb molecule to react with some residues to form an adduct by coordination and electrostatic forces. The coordination of [Hg(SCN)4]2− with Trp was the major cause of the fluorescence quenching of Hb.