Water-soluble receptors for cyclic-AMP and their use for evaluating phosphate-guanidinium interactions

Article abstract of DOI:10.1021/ja00087a013

A water-soluble receptor for adenosine derivatives was synthesized for the study of molecular recognition in aqueous solution. The modular receptor makes use of hydrophobic interactions, Watson-Crick and Hoogsteen hydrogen-bonding, and a phosphate-guanidinium electrostatic interaction to bind cyclic adenosine monophosphates. Measured binding affinities of 2′,3′-cAMP are-3.65 and -3.26 kcal/mol at 51 and 501 mM ionic strength, respectively (H₂O/D₂O solution at 10 °C, pH 6.0). The phosphate-guanidinium interaction in this system is estimated to contribute on average 0.6 kcal/mol (51 mM ionic strength) and 0.3 kcal/mol (501 mM ionic strength) to binding. The maximum value of a phosphate-guanidinium electrostatic interaction is estimated to be 2.4 kcal/mol in water.