Reaction of nucleic acid bases with the mercury electrode: determination of submicromolar concentrations of pyrimidine bases by means of cathodic stripping voltammetry

Abstract

Pyrimidine bases commonly occurring in nucleic acids i.e. cytosine, uracil and thymine and further pyrimidine derivatives such as 5-methylcytosine, 5-hydroxymethylcytosine, isocytosine, uracil-6-carboxylic acid (orotic acid), 5-amino-2,4-dioxypyrimidine, 2-amino-4,6-dioxypyrimidine and 4-amino-2,6-dioxypyrimidine and thio derivatives and halogen derivatives of uracil and cytosine were analyzed by means of cathodic stripping voltammetry (CSV). As compared with most of the sulphur-containing substances the deposition potential optima of the pyrimidine derivatives (not containing sulphur) were substantially narrower and shifted to more positive potentials. Cytosine, thymine and uracil can be determined by means of differential pulse CSV at concentrations of the order of magnitude 10^-7 - 10^-8 mol/l. Nucleosides and nucleotides derived from the pyrimidine bases are inactive and do not substantially interfere with the determination of bases. Bases can be determined even in an excess of DNA and proteins.