Intramolecular Association of 1,N6-Ethenoadenylyl-(3'-->5')-1,N6-ethenoadenosine (εApεA). A Comparison of Intramolecular Stacking Equilibrium Quotients Estimated by Different Methods

Article abstract of DOI:10.1021/ja00537a026

Two approaches were taken to determine the intramolecular stacking equilibrium quotients in aqueous solution at 25 deg C for 1,N⁶-ethenoadenylyl-(3'-->5')-1,N⁶-ethenoadenosine (εApεA), one involving measurements of the temperature dependence of the ultraviolet absorption spectrum and the other, measurements of the ionization constants of εApεA and the component monomers.The values estimated by these two alternative methods are in agreement with the previous finding based on fluorescence techniques, strongly indicating the validity of the so-called "two-state model" for the intramolecular stacking equilibrium system of εApεA.These values of the equilibrium quotient for the intramolecular stacking association of εApεA are also compared with that for the corresponding intermolecular association.