Spectrophotometric studies on the interaction between myricetin and lysozyme in the absence or presence of Cu2+or Fe3+

The binding of myricetin to lysozyme (Lys) in aqueous solution was investigated by fluorescence spectroscopy, ultraviolet–visible absorption spectroscopy (UV) and circular dichroism (CD) spectra under physiological conditions. There are also many metal ions present in body, thus the research about the effect of metal ions on the interaction of drugs with proteins is crucial. In this study, we have investigated the effect of both familiar metal ions Cu2+ and Fe3+ on the interaction between myricetin and Lys by using spectroscopy technique at pH 7.40, for the first time. Spectrophotometric observations are rationalized in terms of a static quenching process in a static quenching way. The cause of showing upward curvy patterns in Stern–Volmer plots was analyzed. The binding constants and binding sites of myricetin with Lys with or without Cu2+ and Fe3+ at different concentrations of myricetin were calculated. UV/vis measurements on the enzymatic activity of Lys with or without Cu2+ in the absence or presence of myricetin indicated that the interaction between myricetin and Lys led to a reduction in the activity of Lys. Furthermore, the effect of pH on the binding constant of myricetin with Lys was also examined.