VOLTAMMETRIC STUDIES OF THE ADSORPTION AND CONFORMATION OF POLYRIBOCYTIDYLIC ACID AT THE MERCURY-ELECTRODE SURFACE

The adsorption and interfacial behaviour of polyribocytidylic acid (poly-C) was studied by phase sensitive ac voltammetry and single-sweep voltammetry. The two helical conformations of poly-C were investigated as a function of various parameters such as pH, adsorption potential, temperature and the nature of the anions of supporting electrolyte. The adsorbed acid form of poly-C undergoes an opening of the double helix because the electric field at the charged interface renders some of cytosine moieties accessible for reduction. The limiting value of the surface concentration of poly-C indicates that the adsorption occurs via the base residues attached to the nucleotide chain. The results are compared with the similar adsorption behaviour of polyriboadenylic acid (poly-A) and DNA.