POLAROGRAPHY OF POLYNUCLEOTIDES - NONREDUCIBILITY OF DOUBLE-STRANDED POLY(GUANYLIC ACID) POLY(CYTIDYLIC ACID)

It has been shown that the thermally labile double-stranded polyribonucleotides poly(adenylic acid) · poly(uridylic acid) and poly(cytidylic acid) · poly(inosinic acid) produce differential pulse polarographic (DPP) peaks analogous to the DPP peak II of double-stranded deoxyribonucleic acid. On the other hand the thermally most stable poly(guanylic acid) · poly(cytidylic acid) is DPP inactive. The DPP inactivity of the latter double-stranded polynucleotide has been observed under a wide variety of conditions (pH, μ and temperature). A.c. polarographic and normal pulse polarographic measurements at DME and linear sweep voltammetry at HMDE have shown that the observed DPP inactivity of this polynucleotide may be connected with its desorption from the electrode at potentials more positive than those of DNA desorption. It has been assumed that this behaviour is caused by too small an amount of bases in poly(guanylic acid) · poly(cytidylic acid) primarily available for the interaction with the electrode surface. It has been demonstrated that DPP sensitively reflects formation of the double-stranded polyribunocleotides. In the case of poly(adenylic acid) · poly(uridylic acid) and poly(guanylic acid) · poly(cytidylic acid) it is possible to detect traces of single-stranded material in a double-stranded polynucleotide sample. © 1979 Elsevier Sequoia S.A.