Base stacking interactions of L-histidine and thyrotropin-releasing hormone with adenosine-5′-monophosphate

Abstract

The selective recognition of particular mononucleotides by certain proteins or enzymes must involve direct interactions between the nucleotides and individual amino acyl residues. The participation of ammo acyl sidechains in localized electrostatic or hydrogen bonding interactions with nucleic acid components is much better understood [ 1,2] than their involvement in delocalized phenomena such as hydrophobic or base stacking interactions. Tryptophan and related indole derivatives [3-91 as well as tyrosine and related phenol derivatives [IO12 ] have been shown to interact with purine nucleotides in aqueous solution. However, there is no experimental evidence that histidine is able to undergo such stacking, although the complex involvement of histidine in proton transfer reactions is well investigated [ 131. We report here a ‘H NMR study which confirms the involvement of histidine and of the histidinecontaining tripeptide TRH in a specific complex with the base moiety of adenine nucleotides.