Electrospray ionization mass spectrometric study of thallium complexes with nucleosides

Abstract

The complexes between Tl+, K+, and nucleosides were studied by using electrospray ionization mass spectrometry. It was found that for complexes of 1:1 stoichiometry, thallium complexes with cytidine were the most abundant and thallium complexes with guanosine were the second most abundant ones. The relative abundances of cytidine–Tl+ to cytidine–K+ complexes depended on stoichiometry (at higher stoichiometry the potassium complexes were more abundant). In other words, the relative affinity of Tl+ and K+ to form cytidine complexes depends on the stoichiometry of the formed complexes. Guanosine–Tl+ complexes were more abundant than guanosine–K+ complexes, irrespective of stoichiometry. Both guanosine tetramer and mixed cytidine/guanosine tetramer were more abundant when they were stabilized by thallium than potassium. Therefore, Tl+ may affect the K+ stabilization of these tetramers.