大米蛋白与米渣蛋白对镉结合能力的对比研究

目的:比较大米蛋白和米渣蛋白对镉的结合能力,探究蛋白对镉的结合机理。方法:通过蛋白对镉的结合试验、镉的脱除试验,比较两种蛋白对镉的结合能力,并用粒径仪、圆二色光谱仪(CD)、红外光谱仪(FTIR)、扫描电子显微镜(SEM)、X射线光电子能谱分析仪(XPS)等仪器分析蛋白与镉的结合机理。通过掩蔽蛋白羧基、氧化巯基后再对镉结合的试验,验证蛋白的羧基及巯基对镉结合的重要性。结果:米渣蛋白对镉的最大结合量为12.08 mg/g,被结合的镉120 min后脱除率达到最大,大米蛋白对镉的最大结合量为8.85 mg/g,被结合的镉60 min后脱除率达到最大。掩蔽蛋白羧基后,两种蛋白对镉的结合量较羧基掩蔽前均下降18%;氧化巯基后,大米蛋白和米渣蛋白较巯基被氧化前对镉的结合量分别下降40%和50%。SEM观察出,蛋白结合镉后发生聚集现象。结论:与大米蛋白相比,米渣蛋白对镉的结合能力更强。此外,两种蛋白对镉的结合不仅是简单的物理吸附作用,蛋白中的巯基和羧基对镉的结合也具有重要作用。

Comparison of the Binding Ability to Cadmium between Rice Protein and Rice Dreg Protein

Objective: To compare the binding ability to cadmium of rice protein and rice dreg protein,and investigate the binding mechanism of protein to cadmium.Methods: The binding ability of proteins was compared by the binding amounts of two proteins to cadmium and the degree of removing cadmium bounded to protein.The size analyzer,circular dichroism spectrometer( CD),infrared spectrometer( FTIR),scanning electron microscope( SEM) and X-ray photoelectron spectroscopy( XPS) were used to analyze the binding mechanism of protein to cadmium.The importance of carboxyl and sulfhydryl groups of proteins to cadmium binding was verified by the cadmium binding test after masking carboxyl and sulfhydryl groups of proteins.Results:The maximum binding amount of rice dreg protein to cadmium was 12.08 mg/g,and the removal rate reached the maximum after 120 min. The maximum binding amount of rice protein to cadmium was 8.85 mg/g,and the combined cadmium was removed after 60 min.After masking the carboxyl group of protein,the binding amount of cadmium to both proteins decreased by18% compared with before masking.After oxidation of sulfhydryl group,the binding amount of rice protein and rice dreg protein to cadmium decreased by 40% and 50%,respectively,compared with that before oxidation of sulfhydryl group. The SEM morphology observed that protein aggregated after binding to cadmium.Conclusion: Compared with rice protein,rice dreg protein had strong binding ability to cadmium.In addition,the binding of the two proteins to cadmium was not only a simple physical adsorption,but also the sulfhydryl and carboxyl groups in the protein played an important role in the binding of cadmium.