DEPROTONATION ENERGETICS OF SOME NUCLEOSIDES IN WATER FROM EMF-MEASUREMENTS

The deprotonation constants of uridine (K-1 and K-2), thymidine (K-1 a nd K-2), cytidine (K-1 and K-2), guanosine (K-1, K-2, and K-3), and xa nthosine (K-1, K-2, and K-3) have been obtained in water from EMF meas urements of Harned-Ehler type cells comprising H-2 and Ag-AgI electrod es at different temperatures, The pK values were substituted in the te mperature equation: pK = AT(-1) + B + CT and A, B, and C were obtained by the method of least squares. Related thermodynamic quantities viz. Delta G(0), T Delta S-0, and Delta H-0 were obtained from coefficient s A, B, and C of the respective nucleosides.