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目的运用荧光光谱法研究镉离子(Cd2+)与人血清白蛋白在不同温度、浓度下的相互作用。方法温度为298 K、304 K、310 K、314 K时,在HSA中逐步加入Cd2+,分别测定各条件下HSA及混合样品的荧光光谱。结果随着Cd2+浓度的增大,HSA发射峰略有红移,荧光强度降低;随着温度增高,HSA猝灭程度加大;温度从298 K升至310 K时,KSV逐步减小,结合常数、结合位点逐步增大,而当温度升高至314 K时,结合常数、结合位点数反而下降;反应中的焓变ΔH>0、熵变ΔS>0且吉布斯自由能变ΔG<0。结论 Cd2+对HSA荧光猝灭机制可能为静态猝灭和动态猝灭同时存在。温度升高至310 K时,Cd2+与HSA的作用增强,两者之间的作用力主要为疏水作用,而到314 K时则表现出动态猝灭的特征。
Objective To study the interaction of Cd2 + and human serum albumin at different temperature and concentration by fluorescence spectroscopy. When the temperature was 298 K, 304 K, 310 K, 314 K, Cd2 + was added into HSA step by step. The fluorescence spectra of HSA and mixed samples were measured under different conditions. Results With the increase of Cd2 + concentration, the emission peak of HSA slightly red-shifted and the fluorescence intensity decreased. With the increase of temperature, the quenching degree of HSA increased. When the temperature increased from 298 K to 310 K, KSV decreased gradually and the binding constant , And the binding sites increased gradually. When the temperature was increased to 314 K, the binding constants decreased but the enthalpy change ΔH> 0, entropy change ΔS> 0 and Gibbs free energy ΔG < 0. Conclusion The fluorescence quenching mechanism of HSA by Cd2 + may be static quenching and dynamic quenching simultaneously. When the temperature is increased to 310 K, the interaction between Cd2 + and HSA is enhanced. The interaction between Cd2 + and HSA is mainly hydrophobic, while the dynamic quenching is shown at 314 K.