Negative Ion Electrospray Mass Spectrometry of Deoxyribonucleotide Monophosphates

✍ Scribed by H. Hernández

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 775 KB
• Volume: 10
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(199609)10:12<1543::aid-rcm704>3.0.co;2-u

✦ Synopsis

Rd. Leicester LEI 9HN. I JK

Negative ion electrospray ionization mass spectrometry has been applied to the four standard nucleotides found in DNA. The particular effect of source parameters on the spectra obtained using a pneumaticallyassisted electrospray source is described. 'In-source' collision-induced dissociation (CID), brought about by an increase in the source cone voltage, caused extensive fragmentation, to yield structurally-signifiant fragments. From a comparison of the 'in-source' CID spectra, it was apparent that the 3'-monophosphates underwent fragmentation more readily than the 5-monophosphates. Tandem mass spectra (MS/MS) were similar to those obtained by 'in-source' CID and were compared with MS/MS spectra reported in the literature using fast-atom bombardment ionization, and sector and ion-trap analysers. Differences between the MS/MS techniques were apparent in that the relative intensities of base and m/z 195 (ribose phosphate) fragments were greater in the data reported here.

Cone voltage is also important, together with control of the capillary voltage, in the formation of doubly charged ions, [M -2H]'-, for all the nucleotides studied, although the extent to which these ions form has been found to be dependent 00 the nucleobase and the position of the phosphate group. The possible influence of base pK, values is evaluated with respect to the doubly charged ions.