Title: 446 — Electrochemical examination of nucleoside interaction Adenosine—guanosine and cytidine—guanosine
Abstract: The adsorption at the solution/mercury electrode interface of guanosine, adenosine and cytidine alone and in guanosine-adenosine and guanosine-cytidine mixtures was examined for pH 4.0 and 7.2 solutions at 25 and 40°C; the principal index used was the a.c. polarographic quadrature current component. All of the nucleosides are adsorbed at the 1.0 mM and lower concentrations examined. There is evidence at 25°C for:o(a)the self-association of uncharged adsorbed guanosine;(b)formation at pH 4 of a 2: 1 guanosine-adenosine complex, which is at least partially positively charged, is more stable than the self-associated guanosine and associates in the adsorbed state;(c)formation at pH 7.2 of a similar 2:1 but uncharged guanosine-adenosine complex;(d)formation of a probably positively charged 1:1 guanosine-cytidine complex, which adsorbs and associates at pH 4 and of a similar neutral complex at pH 7.2 the self-association of uncharged adsorbed guanosine; formation at pH 4 of a 2: 1 guanosine-adenosine complex, which is at least partially positively charged, is more stable than the self-associated guanosine and associates in the adsorbed state; formation at pH 7.2 of a similar 2:1 but uncharged guanosine-adenosine complex; formation of a probably positively charged 1:1 guanosine-cytidine complex, which adsorbs and associates at pH 4 and of a similar neutral complex at pH 7.2 Association of the adsorbed species is not seen at 40°C. The controlling factor in determining the differential capacitance at the interface is generally the presence of the most surface-active species, guanosine.