Sugawara Kazuharu, Yugami Asako, Kadoya Toshihiko
Maebashi Institute of Technology, Gunma, Japan.
Anal Sci. 2012;28(3):251-5. doi: 10.2116/analsci.28.251.
The voltammetric detection of phosphoproteins was developed using a gallium(III) acetylacetonate-modified carbon paste electrode. Because phosphate groups of the protein interacted with the gallium(III) ion, the protein was accumulated on the electrode surface. A hexaammine ruthenium(III) ion, which combined with the functional groups, was used to monitor the interaction. When phosvitin and hexaammine ruthenium(III) ions were incubated in 0.1 M acetate buffer (pH 3.2), a reduction peak of hexaammine ruthenium(III) ion at the electrode decreased as the concentration of the protein increased. In contrast, an increase in the peak current was observed with a plain carbon paste electrode. These results were caused by a competitive reaction of the phosphate groups with the hexaammine ruthenium(III) and gallium(III) ions. In the presence of α-, β- and κ-caseins, the electrode response decreased due to the order of the numbers of phosphate groups. This method could be applied to the sensing of phosphoproteins at the 10(-10) M level.
