Study of interaction between protein and main active components in Citrus aurantium L. by optical spectroscopy

The interaction between flavonoids and proteins was investigated by fluorescence and absorption spectroscopy. The binding parameters of drugs with proteins were obtained according to the corrected fluorescence data by an improved calculation method. The ΔH, ΔS and ΔG obtained indicate that the van der Waals or hydrogen bond, electrostatic force and hydrophobic forces all play a role in the interaction of drugs with proteins. Based on Försterʹs theory, the binding average distance r between the protein and drug was evaluated and found to be less than 3 nm. The interaction of drug–metal ion complexes and proteins was also investigated.