| Abstract: | Polyadenylic acid forms both 1 : 1 and 2 : 1 complexes with 3-methylxanthine under appropriate conditions. While the binding isotherms for formation of these complexes are typical of strongly cooperative processes, their melting profiles are anomalous and indicate that intermediate species are present during the thermal dissociation process. Theobromine and theophylline do not form complexes with polyadenylic acid under similar conditions, and they do not hydrogen-bond very strongly with 9-ethyludenine in chloroform solution. |
