Analytical Sciences

A MutS Protein-immobilized Au Electrode for Detecting Single-base Mismatch of DNA

Aishan HAN,* Tohru TAKARADA,** Taiki SHIBATA,* Masamichi NAKAYAMA,* and Mizuo MAEDA*^,**

*Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
**Bioengineering Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

A novel electrochemical biosensor was developed to detect gene mutation by using a DNA-mismatch binding protein: MutS from Escherichia coli. The MutS protein was immobilized onto an Au-electrode surface via complex formation between a histidine tag of the MutS protein and a thiol-modified nitrilotriacetic acid chemically adsorbed on the Au-electrode surface. When a target double-stranded DNA having a single-base mismatch was captured by the MutS protein on the electrode, some electrostatic repulsion arose between polyanionic DNA strands and anionic redox couple ions. Consequently, their redox peak currents on a cyclic voltammogram with the Au electrode drastically decreased, depending on the concentration of the target DNA, according to the redox couple-mediated artificial ion-channel principle. By using this assay, one can detect all types of single-base mismatch and single-base deletion.

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