Differential pulse polarographic determination of adenylyl-(3′,5′)-guanosine and the effect of some transition metal ions

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Adenine oligonucleotides are compounds of great biological importance. Their electroreduction behaviour is important from both an analytical and a mechanistic view. The electrochemical behaviour at the mercury electrode was reviewed by Janik and Elving and co-workers [l-4]. A sensitive electroanalytical method is required for the quantitative determination of adenine oligonucleotides in biological systems. The polarographic behaviour of diand oligonucleotides was investigated extensively by various authors [2,3,5-91. They have clarified the electrochemical and adsorption behaviour of a series of adenine-, guanineand cytosine-based dinucleotides. The reduction products are similar to those of the free bases except as affected by the rates of intervening chemical reactions. Also, the adsorption effects of such compounds at the mercury electrode surface are very strong, suggesting the presence of more adsorption sites and possible ring interactions in the stacked configuration. Differential pulse polarography (DPP) has been used for the determination of some nucleic acid bases and their nucleosides and nucleotides at trace level concentrations [lo-141. DPP was applied also to the analytical determination of some cytosine dinucleotides and polycytidylic acid [12,15]. Recently, cathodic stripping voltammetry (CSV) has been used for the determination of some nucleic acid bases and other purine and pyrimidine derivatives at concentrations as low as 0.01-0.001 PM [9,16-181. The present work investigates the applicability of DPP for the quantitative trace determination of adenylyl-(3’S’)-guanosine (ApG) as a basis for analytical determination of adenine oligonucleotides. It shoud be mentioned that the binding sites, i.e. bases and phosphate groups of DNA and its components with respect to transition metal ion complexation, have been discussed previously [19-231. Recently, the interaction of some nucleic acid components (bases, nucleosides and