Spectroscopic studies on the interaction of hypocrellin A and hemoglobin

The spectrophotometric and spectrofluorimetric studies revealed that hemoglobin (Hb) could interact with hypocrellin A, a photosensitizing drug used in photodynamic therapy. It was found that this kind of interaction can induce the conformational changes in Hb. In addition, based on fluorescence quenching titration and electron paramagnetic resonance spectroscopy results, the binding parameters, thermodynamic parameters are obtained. The quenching mechanism is also proposed.