Proton magnetic resonance study of 8-(6-aminohexyl)-aminoadenosine 5′-monophosphate

The nucleotide 8-(6-aminohexyl)-amino adenosine 5′-monophosphate (8-AHA-AMP) has been investigated by 220-MHz proton magnetic resonance spectroscopy. The conformation and ionization state of the nucleotide have been determined. The anti-conformation about the glycosyl bond is the preferred form. The interaction between the hexyldiamino chain and the ribose moiety in this conformation gives rise to unusual ribosyl conformation results. The distribution of conformations about the glycosyl bond has little influence on the effectiveness of this nucleotide analog in the purification of dehydrogenases by affinity chromatography. The chemical shift dependence on pH has been carried out on 8-methylaminoadenosine 5′-monophosphate. The 8-aminoadenine ring is protonated at N1 (pK_α 5.0) and at N7 (pK_α 1.5) in acidic solutions. The protonation at N7 is apparently stabilized by a delocalization of charge onto the 8-amino group. The neutrality of the 8-aminoadenine ring at physiological pH is consistent with the effcient binding of the nucleotide by dehydrogenases. An improved method for the preparation of the 8-AHA-AMP is described.