X-ray absorption spectra of nucleotides (AMP, GMP, and CMP) in liquid water solutions near the nitrogen K-edge

The X-ray absorption of nucleotides (adenosine-5′-monophosphate, guanosine 5′-monophosphate, and cytidine 5′-monophosphate) are measured in both water solutions and thin solid films at X-ray energies near the nitrogen K-edge in the ‘water-window’ region. Each spectrum corresponds to the selective excitation of a nucleobase site in a nucleotide, and thus has features similar to the spectrum of the corresponding nucleobase. An additional new peak in the energy region of the nitrogen 1s → π* resonance is observed for each nucleotide. No significant difference between the water solutions and thin solid films is found, which might be attributable to the hydrophobic properties of a nucleobase in a nucleotide.