Electrochemical Analysis of Guanine Base in the Yeast Cell

The cellular harm or mutation results from the indirect reaction through reactive oxygen species (ROS) generated by ultraviolet (UV) ray or direct reaction (such as cyclobutane pyrimidine dimmer (CPD) and 6-4 photoproduct). The amount of intracellular guanine nucleotide irradiated by the 0-80 J/m2 UV-C (254 nm) was measured by means of cyclic voltammetry (CV). The oxidation current peak of intracellular guanine nucleotide was observed. The current peak which reflects the concentration of intracellular guanine base decreased to about 80% of initial value with 80 J/m2 of UV-irradiation. The concentration of guanine nucleotide could be estimated from the oxidation peak current in CV. Moreover, formation of 8-oxodG was estimated by the increase in the mutation frequency from UV-irradiated cells of base excision repair deficient strain. It was shown that the decrease in the peak current is due to the oxidation of the guanine base. This analytical method is useful for the elucidation of the oxidation mechanism of the cell and biological tissues.