科研之友
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摘要
The effect of Zn2+ on the interactions between Quercetin (Que), Myricetin (Myr), two typical naturally occurring biologically-active molecules, and bovine serum albumin (BSA) was investigated by means of fluorescence, infrared and ultraviolet spectroscopic methods. The fluorescence intensity of BSA decreased remarkably upon addition of both Que and Myr, respectively, exhibiting that each compound binds to BSA in aqueous solution. When appropriate amount of Zn2+ was added to the mixture of BSA and Que or Myr, the fluorescence of BSA decreased again accompanied by appreciable blue-shift of its maximum emission wavelength, among which the changes resulted by Myr are more noticeable than Que. The results indicate that Zn2+ can exert some effects on the interactions of both Myr and Que with BSA, and the effects are related to the number of the hydroxyl in B ring of the molecule. The quantitative calculation shows that the binding constant and the number of binding sites of both compounds decreases in the presence of Zn2+ of binds. The infrared spectrum and ultraviolet spectra indicate that Zn2+ binds to both Que and Myr, forming Zn2+ complex, respectively. The effect of Zn2+ on the interactions of Que, Myr with BSA in aqueous solution may be ascribed to the zinc complex formation. Increasing number of hydroxyl in B ring of the flavones-type compounds such as Que and Myr may increase their affinity to BSA. However, the presence of Zn2+ may decrease their binding ability.
