Inosine octamer stabilized by alkali earth metal cations - as studied by electrospray ionization mass spectrometry.

By using electrospray ionization mass spectrometry, inosine was found to be able to form an octamer stabilized by alkali earth metal cation, namely Ca(2+), Sr(2+) and Ba(2+), of which the most stable is that stabilized by Ca(2+) (ion I8+Ca). It was established that 9-methylhypoxanthine (M) did not form an analogical octamer, since ion M8+Ca was not detected. On the other hand, 9-methylhypoxanthine can form "mixed" octamers together with inosine (ions InMm+Ca, n + m = 8, were detected).