Ditopic binding of nucleotides by heptakis(6-hydroxyethylamino-6-deoxy)-β-cyclodextrin

Abstract
The potential of heptakis(6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor capable of electrostatic interaction and hydrogen bonding by its amino side-chains, together with inclusion in its hydrophobic cavity, has been assessed for nucleotides as guest molecules. The interaction of 1 with adenosine-5′-triphosphate (ATP) and adenosine-5′-monophosphate (AMP) has been studied by potentiometry in water. Exceptionally strong binding is observed for fully protonated 1 with ATP4– (K = 1010 M–1) relative to AMP2– (K = 106 M–1), consistent with stronger electrostatic interaction with the former. Binding of AMP and p-nitrophenyl phosphate is of the same order of magnitude, while the complexes formed with ribose-5-phosphate are much weaker. The NMR changes observed upon addition of the nucleotides to 1 confirm interaction with the amino sites, together with inclusion in the cyclodextrin cavity.
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