Electrochemical study on the interaction between biological molecules

为了评估蛋白质与其配体之间的结合事件，构建了覆盖有蛋白质/生物材料膜的电极。甲壳素和胶原具有良好的生物相容性，可作为细胞表面的替代物。利用生物材料中的质子化官能团与带负电荷的蛋白质之间的静电相互作用，将具有分子识别功能的蛋白质固定化，并在甲壳素膜电极上测定了链霉亲和素（pI5.0）-生物素的结合。当用链霉亲和素修饰的电极在含有电活性化合物标记的生物素的溶液中孵育时，由于电极活性部分保持在链霉亲和素与生物素的结合位点，LB的峰电流降低。相反，只有标签的电极响应没有变化。结果表明，LB膜与链霉亲和素结合固定在甲壳素膜表面，利用胶原膜研究了凝集素与糖的相互作用。凝集素与糖的结合与生理过程有关。伴刀豆球蛋白A（ConA）是凝集素的一种，识别甘露糖部分。因此，制备了具有电活性化合物的甘露糖。用ConA/胶原膜修饰的电极与ConA标记的甘露糖结合，使标记的甘露糖峰电流降低。另一方面，未观察到标记半乳糖和标记葡萄糖的峰电流降低。因此，ConA被固定在甲壳素膜表面，并实现了结合的监测。因此，生物聚合物是强大的蛋白质-配体结合的反应场。这一概念将被应用于设计传感器，评估蛋白质-lignd结合在体内。

To evaluate binding event between protein and its ligand, an electrode covered with a protein/biomaterial film was constructed. Chitin and collagen, which have a high biocompatibility, were used as a substitute of cell surface. The protein having molecular recognition function was immobilized on the basis of electrostatic interaction between the protonated functional group in the biomaterial and the negative charged protein.Evaluation of streptavidin(pI 5.0)-biotin binding was attempted at an electrode covered with chitin film. When the electrode modified with streptavidin was incubated in a solution containing biotin labeled with an electroactive compound, the peak current of LB decreased by holding of the electrode active moiety in the binding site of streptavidin to biotin. In contrast, the electrode response of only label did not change. The result showed that the LB combined with streptavidin immobilized on chitin film surface.Using collagen film, investigation of lectin-sugar interaction was carried out. The lectin-sugar binding relates to physiological process. Concanavalin A (Con A), which is one of lectins, recognizes mannose moiety. Therefore, mannose with an electroactive compound was prepared. Con A-labeled mannose binding at an electrode covered with Con A/collagen film made the peak current of labeled mannose decrease. On the other hand, the decrease of peak current of labeled galactose and labeled glucose was not observed. Thus, Con A was immobilized on the chitin film surface, and monitoring of the binding was achieved.Consequently, the biopolymers are powerful as a reaction field for a protein-ligand binding. This concept would be applied to design of sensor that evaluates the protein-lignd binding in vivo.