CHARGE REDUCTION OF OLIGONUCLEOTIDE ANIONS VIA GAS-PHASE ELECTRON-TRANSFER TO XENON CATIONS

Multiply-charged anions derived from electrospray (ES) ionization of t he oligonucleotide 5'-d(GTCTTAGCGCTAAGAC)-3' have been subjected to el ectron transfer reactions with ionized xenon in a quadrupole ion frap and found to undergo minimal fragmentation, This observation stands in contrast with electron transfer to rare gases from anions of smaller oligonucleotides which have been shown to undergo extensive fragmentat ion, The present results are attributed to longer anion lifetimes for the larger oligonucleotide anions (following highly exothermic electro n transfer) which then allow for collisional cooling by the helium bat h gas, Reduction to singly charged anions with minimal fragmentation i s noted, indicating that xenon cations can be considered as a reagent for simplifying ES mass spectra of moderately sized oligonucleotides. The relative merits of the use of xenon cations in the quadrupole ion trap for this purpose is discussed. (C) 1997 by John Whey & Sons, Ltd. This paper was prepared under the-auspices of the US Government and i t is therefore not subject to copyright in the US.