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，构建了覆盖蛋白质/生物材料薄膜的电极。利用甲壳素和胶原蛋白作为细胞表面的替代物，具有较高的生物相容性。利用生物材料中质子化官能团与负电荷蛋白之间的静电相互作用，固定化了具有分子识别功能的蛋白。在几丁质膜覆盖的电极上，尝试评价链霉亲和素（pI 5.0）与生物素的结合。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，通过保持链霉亲和素与生物素结合位点的电极活性部分，LB的峰值电流降低。相比之下，只有标签的电极响应没有变化。结果表明，LB与链霉亲和素结合在几丁质膜表面固定化。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。甘露糖蛋白A （cona）是一种凝集素，可识别甘露糖部分。因此，制备了具有电活性化合物的甘露糖。Con A标记的甘露糖在覆盖Con A/胶原膜的电极上结合，使标记甘露糖的峰值电流降低。另一方面，标记半乳糖和标记葡萄糖的峰值电流没有下降。因此，将Con A固定在甲壳素膜表面，实现了对其结合的监测。因此，生物聚合物作为蛋白质-配体结合的反应场是强大的。这一概念可应用于蛋白质与木质素结合的传感器设计。

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.