Dear Editor, New tetrads formed by deprotonated guanosine molecules and stabilized by alkali earth metal cations, as studied by electrospray ionization mass spectrometry

摘要

From the biological point of view, a very important property of guanine is its ability to form a tetramer, called guanine tetrad, which is stabilized by alkali metal cations, sodium and potassium. Guanine or guanosine tetrads have been successfully analyzed by electrospray ionization mass spectrometry (ESI-MS).~([1-4]) Recently, Sravani et al.~([5]) have shown, by ESI-MS, that deoxyguanosine tetrad can be also stabilized by alkali earth metal cations, namely Ca~(2+), Sr~(2+) and Ba~(2+) (when two tetrads are stabilized by a metal cation we deal with an octamer~([5,6])). There are a few papers reporting the use of ESI-MS to study the complexes between pyrimidine bases (uracil, thymine, cytosine) and alkali earth metal cations, mainly Ca~(2+.[7-9]) Most of the complexes between the nucleobase and alkali earth metal cations involve neutral nucleobase molecules; however, uracil and thymine are also prone to form complexes as deprotonated molecules.~([9,10])