Association Constants of Guanine Oligomers with Alkali Metal Ions Studied by Atmospheric Pressure Droplet IR-Laser Ablation Mass Spectrometry

Abstract

Guanine (G) molecules form a stable tetramer with a metal ion, G-quartet. We observed the G-quartet by atmospheric pressure droplet IR-laser ablation mass spectrometry, which enables us to analyze the abundance of chemical species in solutions. We estimated association constants of Gn and M+ (M+ = Li+, Na+, and K+) from intensities of G1-5H+ and G1-4M+ in the obtained mass spectra. The larger association constants of G4 than those of Gn (n ≠ 4) indicate G-quartets' stability.