Spectroscopic Properties Of Heavy Metal Ions With Keyhole Limpet Hemocyanin Interactions

Hemocyanin is a kind of respiratory proteins in mollusks. It’s significant to study theinteraction bwteen heavy metal ion and keyhole hemocyanin. It can provide the mechanism ofheavy metal toxic effects on proteins. In this paper, UV-vis absorption spectra, fluorescencespectra and cyclic voltammetry were used in the study of interaction between heavy metal ionsincluding Hg（II）, Cd（II）, Cu（II）, Pb（II） and keyhole hemocyanin from the marine molluskMegathura-crenulata.Chapter1, Review. In this chapter, it reviewed the study of hemocyanin and heavy metalelments. The methods of heavy metal elements and proteins actions were introduced respectively.Chapter2, Fluorescence study on the interaction of keyhole limpet hemocyanin with Hg （II）ion. By the study of UV-vis spectra, the change of hemocyanin conformational was found by theincreasing absorption in210nm wavelength with increase Hg （II） contention in the solution.Fluorescence quenching spectrometry was applied to investigate the mechanism of the interaction,and the result revealed that at pH=7.4tris （hydroxymethyl） aminomethane buffered saline thefluorescence of KLH decreased evidently with the addition concentration of Hg （II）. According tothe plot of Stern-Volmer, the constants Ksv and Kq at298K were8.04×10⁴and8.04×10¹²respectively. It was proved that the process of interaction between Hg （II） and KLH is a staticquenching. Meanwhile, the binding constant and the binding number are1.53×10⁴L/mol and0.9053. At differ temperatures, the binding constants changes and thermodynamic permanents ΔH,ΔG and ΔS confirmed a hydrophobic reaction between Hg （II） and KLH. Moreover, UV-visabsorption and synchronous fluorescence proved all the result above. In the cyclic voltammetrystudy, Hg （II） ion oxidation current amount decreased.Chapter3, A study on the interaction of keyhole limpet hemocyanin with Cd （II） ion byFluorescence spectrum. By the results of UV-vis spectra, a little change of hemocyaninconformational was found in210nm wavelength with increase Cd （II） ion contention.Fluorescence quenching spectrometry was applied to survey the mechanism of the interaction, andthe result revealed that the fluorescence of KLH decreased evidently by the addition concentrationof Cd （II） ion. According to the plot of Stern-Volmer, the constants Ksv and Kq at298K were7.82×10⁴and7.82×10¹²respectively. It was demonstrated that the process of interaction betweenCd （II） and KLH is a static quenching. The binding constant is4.76×106L/mol and the bindingnumber was1.3268at room temperature. At differ temperatures, the binding constants changesand corresponding thermodynamic permanents ΔH, ΔG and ΔS confirmed the mainly react is a hydrogen bonding or van der Waals react. Moreover, UV-vis absorption and synchronousfluorescence proved all the result above. In the cyclic voltammetry study, Cd （II） ion oxidationcurrent amount decreased.Chapter4, Fluorescence study on the interaction of keyhole limpet hemocyanin with Cu （II）ion. By the study of UV-vis spectra, the evident change of hemocyanin conformational was foundby the increasing absorption in210nm wavelength. Fluorescence quenching spectrometrydemonstrated the mechanism of the interaction, and the fluorescence of KLH decreased markedlywith the addition concentration of Cu （II） ion. According to the plot of Stern-Volmer, the constantsKsv and Kq were4.15×10⁴and4.15×10¹². It was proved that the process of interaction betweenCu （II） and KLH is a static quenching. The binding constant and the binding number were6.62×10³L/mol and0.9053at298K. At differ temperatures, the binding constants changes andthermodynamic permanents ΔH, ΔG and ΔS proved a hydrophobic interaction. In the cyclicvoltammetry study, Cu （II） ion oxidation current amount increased.Chapter5, A study on the interaction of keyhole limpet hemocyanin with Pb （II） ion byFluorescence spectrum. With increase Pb （II） ion contention, the evident change of hemocyaninconformational was found especially by the increasing absorption in210nm wavelength by theUV-vis spectra. Fluorescence quenching spectrometry was applied to investigate the mechanism ofthe interaction, and the result revealed that the fluorescence of KLH decreased evidently.According to the plot of Stern-Volmer, the constants Ksv and Kq were3.57×10⁴and3.57×10¹²respectively. It was demonstrated that the interaction is a static quenching. The binding constantand the binding number were2.66×10⁴L/mol and0.9669respectively. At differ temperatures,according to the binding constants change and thermodynamic permanents ΔH, ΔG and ΔS, itproved that it is a hydrogen bonding or van der Waals reaction. In the cyclic voltammetry study,Pb （II） ion oxidation current amount decreased remarkablely.Chapter6, Summary and prospect. It summarized the contents of the primary chapters inUV-vis spectra, fluorescence spectra and electrochemical methods. According to the results, itcompared the differences among Hg （II）, Cd （II）, Cu （II） and Pb （II）, and summarized the regularpatterns.