CYCLIC VOLTAMMETRY WITH RNA-MODIFIED MERCURY-ELECTRODE

RNA was analyzed by means of cyclic voltammetry (CV) in combination wi th a hanging mercury drop electrode (HMDE) using conventional adsorpti ve stripping voltammetry (AdSV) and adsorptive transfer stripping volt ammetry (AdTSV) involving the RNA-modified electrode. The immobilizati on of RNA at HMDE is sufficiently stable and the RNA-modified electrod e can be used for analytical purposes. The immobilized tRNA produces a small faradaic cathodic peak CA (due to reduction of adenine and cyto sine residues) and an anodic peak G (due to guanine) if a neutral medi um containing ammonium ions is used as a background electrolyte. The p otentials of peaks CA and G correspond to those of DNA. Peak G can be used for the determination of RNA and DNA in the mixture if RNA is spe cifically hydrolyzed by ribonuclease A and AdTS CV is performed before and after the enzymatic hydrolysis. The presence of RNase and of the RNA hydrolysate in the analyzed preparation does not interfere with th e analysis, which enables AdTS CV to be performed directly with the hy drolyzed sample without any purification or separation steps. In a wea kly alkaline background electrolyte tRNA produces a cathodic peak at - 1.36 V/SCE which differs by almost 100 mV from the more negative peak of DNA, thus providing the possibility of monitoring RNA and DNA signa ls in the mixture. Submicrogram amounts of RNA and DNA in a mixture ca n easily be analyzed in both neutral and alkaline media.