Subramanian S, Sampath S
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, India.
Biomacromolecules. 2007 Jul;8(7):2120-8. doi: 10.1021/bm0701999. Epub 2007 Jun 14.
Adsorption characteristics of zein protein on hydrophobic and hydrophilic surfaces have been investigated to understand the orientation changes associated with the protein structure on a surface. The protein is adsorbed by a self-assembly procedure on a monolayer-modified gold surface. It is observed that zein shows higher affinity toward hydrophilic than hydrophobic surfaces on the basis of the initial adsorption rate followed by quartz crystal microbalance studies. Reflection absorption infrared (RAIR) spectroscopic studies reveal the orientation changes associated with the adsorbed zein films. Upon adsorption, the protein is found to be denatured and the transformation of alpha-helix to beta-sheet form is inferred. This transformation is pronounced when the protein is adsorbed on hydrophobic surfaces as compared to hydrophilic surfaces. Electrochemical techniques (cyclic voltammetry and impedance techniques) are very useful in assessing the permeability of zein film. It is observed that the zein moieties adsorbed on hydrophilic surfaces are highly impermeable in nature and act as a barrier for small molecules. The topographical features of the deposits before and after adsorption are analyzed by atomic force microscopy. The protein adsorbed on hydrophilic surface shows rod- and disclike features that are likely to be the base units for the growth of cylindrical structures of zein. The thermal stability of the adsorbed zein film has been followed by variable-temperature RAIR measurements.
为了解玉米醇溶蛋白在表面的取向变化及其与蛋白质结构的关系，对其在疏水和亲水表面的吸附特性进行了研究。该蛋白质通过自组装过程吸附在单层修饰的金表面。通过石英晶体微天平研究的初始吸附速率发现，玉米醇溶蛋白对亲水表面的亲和力高于疏水表面。反射吸收红外（RAIR）光谱研究揭示了与吸附的玉米醇溶蛋白膜相关的取向变化。吸附后，发现蛋白质发生变性，并推断α-螺旋向β-折叠形式转变。与亲水表面相比，当蛋白质吸附在疏水表面时，这种转变更为明显。电化学技术（循环伏安法和阻抗技术）在评估玉米醇溶蛋白膜的渗透性方面非常有用。观察到吸附在亲水表面的玉米醇溶蛋白部分本质上是高度不可渗透的，并且对小分子起到屏障作用。通过原子力显微镜分析吸附前后沉积物的形貌特征。吸附在亲水表面的蛋白质呈现出棒状和盘状特征，这可能是玉米醇溶蛋白圆柱形结构生长的基本单元。通过变温RAIR测量跟踪吸附的玉米醇溶蛋白膜的热稳定性。
