Recent developments in the ion/ion chemistry of high‐mass multiply charged ions

Abstract. Non-dissociative charge reduction, typically considered to be an unwanted side reaction in electron transfer dissociation (ETD) experiments, can be enhanced significantly in order to reduce the charge state of intact protein complexes to as low as 1+ on a commercially available Q-IM-TOF instrument. This allows for the detection of large complexes beyond 100,000 m/z, while at the same time generating top-down ETD fragments, which provide sequence information from surface-exposed parts of the folded structure. Optimization of the supplemental activation has proven to be crucial in these experiments and the charge-reduced species are most likely the product of both proton transfer (PTR) and non-dissociative electron transfer (ETnoD) reactions that occur prior to the ion mobility cell. Applications of this approach range from deconvolution of complex spectra to the manipulation of charge states of gas-phase ions.

Section: Resultsmentioning

confidence: 95%

Extensive Charge Reduction and Dissociation of Intact Protein Complexes Following Electron Transfer on a Quadrupole-Ion Mobility-Time-of-Flight MS

Lermyte

Williams

Brown

et al. 2015

“…Ion/ion reactions have been used to study the primary structure of biopolymers through processes such as electron-transfer dissociation (ETD), to manipulate charge states, and to form novel ion types which may not be available directly from ESI [17,18]. Ion/ion reactions can be generally categorized into three types: charge-transfer (including proton and electron-transfer), complex formation, and metal cation exchange.…”

mentioning

confidence: 99%

Gas-phase ion/ion reactions of transition metal complex cations with multiply charged oligodeoxynucleotide anions

Barlow

Hodges

Xia

et al. 2008

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Multiply deprotonated hexadeoxyadenylate anions, (A 6 ϪnH) nϪ , where n ϭ 3-5, have been subjected to reaction with a range of divalent transition-metal complex cations in the gas phase. The cations studied included the bis-and tris-1,10-phenanthroline complexes of Cu II , Fe II , and Co II , as well as the tris-1,10-phenanthroline complex of Ru II . In addition, the hexadeoxyadenylate anions were subjected to reaction with the singly charged Fe III and Co III N,N=-ethylenebis(salicylideneiminato) complexes. The major competing reaction channels are electron-transfer from the oligodeoxynucleotide anion to the cation, the formation of a complex between the anion and cation, and the incorporation of the transition-metal into the oligodeoxynucleotide. The latter process proceeds via the anion/cation complex and involves displacement of the ligand(s) in the transition-metal complex by the oligodeoxynucleotide. Competition between the various reaction channels is governed by the identity of the transition-metal cation, the coordination environment of the metal complex, and the oligodeoxynucleotide charge state. In the case of the divalent metal phenanthroline complexes, competition between electron-transfer and metal ion incorporation is particularly sensitive to the coordination number of the reagent metal complexes. Both electron-transfer and metal ion incorporation occur to significant extents with the bis-phenanthroline ions, whereas the trisphenanthroline ions react predominantly by metal ion incorporation. To our knowledge this work reports the first observations of the gas-phase incorporation of multivalent transition-metal cations into oligodeoxynucleotide anions and represents a means for the selective incorporation of transition-metal counter-ions into gaseous oligodeoxynucleotides. [6 -8] have allowed the formation of gas-phase ions of biopolymers, including oligodeoxynucleotides (ODNs), making these ions amenable to study by mass spectrometry. Like peptides and proteins, ODNs are amphoteric, [9] allowing formation of either positively or negatively charged ions. Formation of negatively charged oligonucleotides is quite facile using ESI and, as a result, negatively charged ODN ions have been the most widely studied [9]. Oligodeoxynucleotide ions with bound metals formed by MALDI or ESI, especially those containing transition metals, have shown fragmentation behavior, which is distinct and complementary to that of ions devoid of metals [6 -8].The study of the interaction of transition metals with DNA is of critical importance, given the variety of roles such interactions fulfill. Transition-metal complexes display nuclease activity and consequently complexes such as (methidium-propyl-EDTA)iron(II) have been utilized as footprinting agents [10]. Ruthenium(II) complexes have been extensively examined as spectroscopic probes of local DNA structure [11,12]. The mechanism of action of the chemotherapeutic agent cisplatin involves binding to DNA to prevent replication [13][14][15]. Mass spectrometry has been u...

“…Both the polarity and the magnitude of the charge associated with an ionized biomolecule play important roles in the use of tandem mass spectrometry for the identification and structural characterization of the biomolecule from which the ions were derived. Ion/ion reactions provide efficient means for manipulating the identities of gas-phase ions after their initial formation [3,4], including altering ion polarity and absolute charge. Applications of charge manipulation via ion/ ion reactions include: mixture analysis [5][6][7][8], especially with the application of the "ion parking" technique for gas-phase concentration and charge state purification [9], the formation of ions that cannot be directly produced by ESI for subsequent tandem mass spectrometry studies [10], and the reduction of the product ion charge states to singly and doubly charged so as to simplify the interpretation of product ion spectra [11][12][13][14][15][16].…”

mentioning

confidence: 99%

Pulsed dual electrospray ionization for In/In reactions

Xia

Liang

McLuckey

2005

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116

A pulsed dual electrospray ionization source has been developed to generate positive and negative ions for subsequent ion/ion reaction experiments. The two sprayers, typically a nano-electrospray emitter for analytes and an electrospray emitter for reagents, are positioned in a parallel fashion close to the sampling orifice of a triple quadrupole/linear ion trap tandem mass spectrometer (Sciex Q TRAP). The potentials applied to each sprayer are alternately pulsed so that ions of opposite polarity are generated separately in time. Ion/ion reactions take place after ions of each polarity are sequentially injected into a high-pressure linear ion trap, where axial trapping is effected by applying an auxiliary radio frequency voltage to the end lenses. The pulsed dual electrospray source allows optimization of each sprayer and can be readily coupled to any spray interface with no need for instrument modifications, provided the potentials required to transmit the ion polarity of interest can be alternated in synchrony with the emitter potentials. Ion/ion reaction examples such as charge reduction of multiply charged protein ions, charge inversion of peptides ions, and protein-protein complex formation are given to illustrate capabilities of the pulsed dual electrospray source in the study of gas-phase ion/ion chemistry. T he advent of electrospray ionization (ESI) mass spectrometry has revolutionized the analysis of many biologically important macromolecules [1,2]. Both the polarity and the magnitude of the charge associated with an ionized biomolecule play important roles in the use of tandem mass spectrometry for the identification and structural characterization of the biomolecule from which the ions were derived. Ion/ion reactions provide efficient means for manipulating the identities of gas-phase ions after their initial formation [3,4], including altering ion polarity and absolute charge. Applications of charge manipulation via ion/ ion reactions include: mixture analysis [5][6][7][8], especially with the application of the "ion parking" technique for gas-phase concentration and charge state purification [9], the formation of ions that cannot be directly produced by ESI for subsequent tandem mass spectrometry studies [10], and the reduction of the product ion charge states to singly and doubly charged so as to simplify the interpretation of product ion spectra [11][12][13][14][15][16]. Electron-transfer ion/ion reactions have recently been described as a means of inducing structurally informative dissociation, giving rise to cleavages analogous to those noted in electron capture dissociation [17][18][19][20][21]. In this regard, ion/ion reactions play a role as a probe of primary structure.Electrodynamic ion traps, either a quadrupole ion trap or a linear ion trap (LIT), are particularly useful reaction vessels for ion/ion reactions because of their ability to store oppositely-charged ions simultaneously [22] as well as their ion isolation and MS n functionalities [23]. Most ion/ion reaction studies involving m...