Interaction of polyadenylic acid with the mercury electrode.

Interactions of polyadenylic acid with the mercury electrode were followed by means of direct current (d.c.), alternating current (a.c.), and pulse polarography. It was ascertained that the electrode reaction of polyadenylic acid did not differ significantly from the reaction of its monomeric components. In contrary to the latter reaction, the polarographic reduction of poly­ adenylic acid takes place only in the adsorbed state. Desorption of polyadenylic acid from the surface of the mercury electrode at negative potentials inhibits the reduction current. Due to this inhibition the d.c. polarographic curves of polyadenylic acid can have the shape of a single maxi­ mum or of a “double-wave”. A method was suggested for a rapid determination of diffusion coef­ ficients of single-stranded polyadenylic acid by means of d.c. polarography. A.c. polarographic measurements yielded data on the adsorption/desorption behaviour of polyadenylic acid, on the basis of which conclusions were made concerning the conformation of polyadenylic acid in solu­ tion. While relatively concentrated solutions of polyadenylic acid must be used in the d.c. and a.c. polarographic studies, a little as 10 —15 ng of polyadenylic acid can be determined by means of pulse polarography.