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Collision‐induced Dissociation of Polyprotonated Oligonucleotides Produced by Electrospray Ionization
Author(s) -
Ni Jinsong,
Mathews Michael A. A.,
McCloskey James A.
Publication year - 1997
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(199704)11:6<535::aid-rcm898>3.0.co;2-p
Subject(s) - phosphodiester bond , chemistry , protonation , oligonucleotide , dissociation (chemistry) , deprotonation , electrospray ionization , mass spectrometry , stereochemistry , mass spectrum , collision induced dissociation , thymine , photochemistry , ion , tandem mass spectrometry , organic chemistry , dna , rna , biochemistry , chromatography , gene
The efficient production of polyprotonated oligonucleotides, studied at n ≤ 19, occurs from water/propan‐2‐ol solutions over an ammonium acetate concentration range between 2.5 and 40 m M and a pH range from 5 to 11. Average charge‐state levels observed were approximately half of those found in mass spectra of polyanionic oligonucleotides, reflecting differences in sites of ionization: heterocyclic bases for protonation and phosphodiester backbone for deprotonation. Collision‐induced dissociation mass spectra show three principal reaction paths: ( 1 ) release of protonated bases, with abundances dictated largely by base proton affinity; ( 2 ) phosphodiester chain cleavage at C3′—O3′ indicative of sequence in the 3′ → 5′ direction; and ( 3 ) chain cleavage concomitant with base loss giving furan‐type ions indicative of sequence in the 5′ → 3′ direction, analogous to reactions of polyanionic oligonucleotides. Thymine residues undergo very little protonation, resulting in characteristic absence of phosphodiester cleavage on the 3′ side of T sites, producing mass‐ladder gaps representing dinucleotides. © 1997 John Wiley & Sons, Ltd.