A fluorimetric study of the interaction of C.I. Solvent Red 24 with haemoglobin

The interaction between bovine haemoglobin and C.I. Solvent Red 24 was investigated by UV/vis absorption, fluorescence, resonance light-scattering spectra, synchronous fluorescence as well as three-dimensional fluorescence spectra techniques at pH 7.4. The dye effectively quenched the intrinsic fluorescence of bovine haemoglobin via static quenching. The process of dye to bovine haemoglobin was spontaneous, the related changes in enthalpy and entropy being 1.78 kJ mol−1, 81.58 J mol−1 K−1 respectively, according to the van't Hoff equation, indicating that hydrophobic interaction played a major role in stabilizing the complex. Synchronous fluorescence spectroscopy and three-dimensional fluorescence spectra showed that the structure of the tyrosine residue environments was altered by the dye which interacted at the α1β2 interface of the bovine haemoglobin molecule.