Voltammetric behaviors of wheat-germ agglutinin on a chitin-modified carbon-paste electrode

The voltammetric behavior of wheat-germ agglutinin (WGA) on a chitin-modified carbon-paste electrode (CPE) was investigated using glucose labeled with an electroactive compound. WGA usually consists of two subunits, each with two binding sites for sugars. WGA was immobilized on the electrode surface by selective binding to a N-acetylglucosamine residue of chitin. Because glucose also combines with WGA, the glucose was coupled with electroactive daunomycin to evaluate the binding. When a WGA-labeled glucose complex was formed, the electroactive moiety became electroinactive. The binding caused a decrease in the peak current of the labeled glucose. In a measurement of only daunomycin used as a label, the peak current in a solution with WGA was similar to that in a solution without WGA. Therefore, it is clear that the labeled glucose was held in the remaining binding site of WGA on the electrode surface. Thus, a CPE modified with chitin would be powerful as a reaction field between sugar and lectin.