A study of the electrochemical behavior of covalently mercurated uridine nucleotides

The electrochemical behavior of the covalently mercurated uridine triphosphate (UTP-HgX), mercurated uridine diphosphate (UDP-HgX), and mercurated uridine monophosphate (UMP-HgX) have been characterized with a hanging mercury drop electrode in aqueous medium with linear and cyclic voltammetry. The voltammetry of these compounds was found to contain two components: diffusional and surface effects. The diffusional component, seen in the form of a large diffusional wave, resulted from the two-electron reduction of the diffusing mercurated nucleotides with the production of the parent compound and metallic mercury. The surface component resulted from the electroactive nucleotide surface layer which self assembles on mercury electrode at open circuit. The Langmuir adsorption isotherm was found to describe this adsorption event the majority of the time. Multiple one-electron surface waves were present during the surface voltammetry. A mechanistic interpretation was provided. The specific mechanism depended on the complexation state of the mercury substituent. Both intramolecular phosphate complexation and chloride complexation were observed. Unique to the mercurated UMP, intermolecular complexation through the nitrogen of the pyrimidine ring was observed to occur resulting in polymerization which dramatically effected the surface voltammetry. From the mechanistic interpretation of the surface voltammetry, Quick Basic programs were constructed to calculate theoretical voltammograms for each mechanism. Calculated and experimental were compared.