木瓜蛋白酶水解对β-酪蛋白膜的形态和黏弹性的影响

Effects of Papain Hydrolysis of β-casein Layer on Morphology and Viscoelasticity

目的:评价木瓜蛋白酶水解对牛β-酪蛋白(β-CN)膜表面形态和黏弹性的影响。方法:将β-CN通过自组装固定于芯片表面,采用消散因子石英晶体微天平(quartz crystal microbalance with dissipation,QCM-D)测量β-CN膜能量消散因子(ΔD)和频率(ΔF)和黏弹性变化。β-CN膜水解前后的表面形态变化通过原子力显微镜(atomic force microscopy,AFM)表征。结果:伴随着酶浓度提高,残余的β-CN膜的黏弹性增加(P<0.05)。AFM图像显示水解后残余的β-CN膜的厚度和粗糙度均降低。结论:木瓜蛋白酶水解β-酪蛋白β-CN膜的反应具有浓度依赖性特征;水解反应使膜变得较薄而光滑,且更加紧凑和较硬。

Objetive： To evaluate the effect of papain hydrolysis of bovine β-casein layer on their morphology and viscoelasticity. Method： β-CN was immobilized on the sensor surface by self-assembled monolayers. The shift in energy dissipation factor （△D）, frequency （△F） and viscoelasticity of β-CN layer were measured by a quartz crystal microbalance with dissipation （QCM-D）. The morphologic changes of β-CN layers before and after hydrolysis were characterized by atomic force microscopy （AFM） imaging. Results： Our results show that the AD decreased with increasing enzyme concentration, which suggests that the viscoelasticity of remaining β-CN layers increased after hydrolysis （P〈0.05）. AFM imaging shows that the thickness and roughness of remaining β-CN layers on the gold surface diminished after hydrolysis. Conclusion： The hydrolysis of β-CN layer has a characteristic of the concentration-dependence of papain. The remaining β-CN layers became thinner and smoother as well as more compact and stiffer due to hydrolytic reaction.