Gas-phase hydrogen/deuterium exchange as a molecular probe for the interaction of methanol and protonated peptides

Gard, Eric E.; Green, M. Kirk; Bregar, Jennifer; Lebrilla, Carlita B.

doi:10.1016/1044-0305(94)85003-8

Cited by 112 publications

(98 citation statements)

References 30 publications

(49 reference statements)

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“…Of the reagents listed here, exchange reactions with ND 3 are the most facile and are thought to occur through an onium ion or tautomer mechanism [13]. D 2 O is generally the slowest reagent and exchange occurs through the relay mechanism in which D 2 O inserts into a proton bridge between two heteroatoms, or the flip-flop mechanism (for carboxylic acid functional groups) [13,14]. The onium ion mechanism is unlikely with D 2 O given its low gas phase basicity.…”

Section: Introductionmentioning

confidence: 99%

Fragmentation of doubly-protonated peptide ion populations labeled by H/D exchange with CD3OD

Herrmann

Kuppannan

Wysocki

2006

International Journal of Mass Spectrometry

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Doubly-protonated bradykinin (RPPGFSPFR) and an angiotensin III analogue (RVYIFPF) were subjected to hydrogen/deuterium (H/D) exchange with CD 3 OD in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. A bimodal distribution of deuterium incorporation was present for bradykinin after H/D exchange for 90 s at a CD 3 OD pressure of 4 × 10 −7 Torr, indicating the existence of at least two distinct populations. Bradykinin ion populations corresponding to 0-2 and 5-11 deuteriums (i.e., D 0 , D 1 , D 2 , D 5 , D 6 , D 7 , D 8 , D 9 , D 10 , and D 11 ) were each monoisotopically selected and fragmented via sustained off-resonance irradiation (SORI) collision-induced dissociation (CID). The D 0 -D 2 ion populations, which correspond to the slower exchanging population, consistently require lower SORI amplitude to achieve a similar precursor ion survival yield as the faster-reacting (D 5 -D 11 ) populations. These results demonstrate that conformation/ protonation motif has an effect on fragmentation efficiency for bradykinin. Also, the partitioning of the deuterium atoms into fragment ions suggests that the C-terminal arginine residue exchanges more rapidly than the N-terminal arginine. Total deuterium incorporation in the b 1 /y 8 and b 2 /y 7 ion pairs matches very closely the theoretical values for all ion populations studied, indicating that the ions of a complementary pair are likely formed during the same fragmentation event, or that no scrambling occurs upon SORI. Deuterium incorporation into the y 1 /a 8 pseudo-ion pair does not closely match the expected theoretical values. The other peptide, doubly-protonated RVYIFPF, has a trimodal distribution of deuterium incorporation upon H/D exchange with CD 3 OD at a pressure of 1 × 10 −7 Torr for 600 s, indicating at least three distinct ion populations. After 90 s of H/D exchange where at least two distinct populations are detected, the D 0 -D 7 ion populations were monoisotopically selected and fragmented via SORI-CID over a range of SORI amplitudes. The precursor ion survival yield as a function of SORI amplitude falls into two distinct behaviors corresponding to slower-and faster-reacting ion populations. The slower-reacting population requires larger SORI amplitudes to achieve the same precursor ion survival yield as the faster exchanging population. Total deuterium incorporation into the y 2 /b 5 ion pairs matches closely the theoretical values over all ion populations and SORI amplitudes studied. This result indicates the y 2 and b 5 ions are likely formed by the same mechanism over the SORI amplitudes studied.

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Section: Introductionmentioning

confidence: 99%

Fragmentation of doubly-protonated peptide ion populations labeled by H/D exchange with CD3OD

Herrmann

Kuppannan

Wysocki

2006

International Journal of Mass Spectrometry

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“…H /D exchange (HDX) is one of the most popular techniques for the structural elucidation of biomolecules in mass spectrometry and has been widely implemented for both solution [1][2][3][4] and gas phase studies [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In solution, the extent of HDX can be directly related to the solvent accessibility of amino acid residues in proteins.…”

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confidence: 99%

“…However, in the gas phase there are many structural parameters apart from the surface availability that affect the HDX rates, as illustrated in a recent HDX study on ion-mobilityselected charge states of bovine ubiquitin [17]. Systematic studies on small peptide systems showed that the difference in proton affinity of the biomolecules and deuterated donor reagent plays a crucial role in the HDX mechanism [7][8][9][10]19]. Beauchamp and coworkers [9] suggested that lower basicity reagents, such as D 2 O and CH 3 OD, proceed via a "relay" mechanism [20] for protonated peptides, while the higher basicity ND 3 reagent gives rise to an "onium" mechanism [21].…”

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confidence: 99%

Observation of zwitterion formation in the gas-phase H/D-exchange with CH₃OD: Solution-phase structures in the gas phase

Polfer

Dunbar

2007

J. Am. Soc. Mass Spectrom.

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Infrared spectroscopy of gas-phase singly deuterated [Trp ϩ K] ϩ (formed by H/D exchange with CH 3 OD) shows that some (ϳ20%) kinetically stable zwitterionic (ZW) conformer is formed, based on the diagnostic antisymmetric CO stretch of the deprotonated carboxylate moiety, as (CO 2 Ϫ ), at 1680 cm Ϫ1 . A majority of the deuterated [Trp ϩ K] ϩ is found to be in the charge solvation (CS) conformation, with deuterium exchange occurring on both the acid and amino groups, which is consistent with H/D scrambling. Interestingly, H/D exchange with the more basic ND 3 reagent did not result in the stabilization of a kinetically stable zwitterion, although it is not clear yet what causes this observation. The result for CH 3 OD shows that H/D exchange can in fact alter the structure of the analyte and, hence, care needs to be taken when interpreting gas-phase H/D exchange studies. Moreover, this result shows the possibility of forming solution-phase structures that are thermodynamically disfavored in the gas phase, thus opening a new area of study. (HDX) is one of the most popular techniques for the structural elucidation of biomolecules in mass spectrometry and has been widely implemented for both solution [1][2][3][4] and gas phase studies [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In solution, the extent of HDX can be directly related to the solvent accessibility of amino acid residues in proteins. However, in the gas phase there are many structural parameters apart from the surface availability that affect the HDX rates, as illustrated in a recent HDX study on ion-mobilityselected charge states of bovine ubiquitin [17]. Systematic studies on small peptide systems showed that the difference in proton affinity of the biomolecules and deuterated donor reagent plays a crucial role in the HDX mechanism [7][8][9][10]19]. Beauchamp and coworkers [9] suggested that lower basicity reagents, such as D 2 O and CH 3 OD, proceed via a "relay" mechanism [20] for protonated peptides, while the higher basicity ND 3 reagent gives rise to an "onium" mechanism [21]. In the case of amino acids cationized by an alkali metal ion rather than a proton, polar deuterating ligands such as D 2 O can exchange via a similar relay mechanism involving charge solvation-zwitterion (CS-ZW) isomerization [18]. Modeling of observed HDX processes and quantum chemical calculations of the potential surfaces have made a strong circumstantial case that ZW structures are traversed in many cases during HDX with basic partners like D 2 O, CH 3 OD, and ND 3 [14,16,18]. Nevertheless, computations also generally indicate that the bare ZW is sufficiently disfavored energetically that its equilibrium presence in the M ϩ /amino acid would be negligible [22,23].Here, we show unambiguous spectroscopic evidence that bare ZW can in fact be kinetically trapped as a result of the HDX of [Trp ϩ K] ϩ with CH 3 OD. Infrared multiple-photon dissociation (IR-MPD) spectroscopy of metal-tagged amino acids and peptides has already been shown to be a powerful probe for CS ...

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“…Mass spectrometry is well suited for the detection of deuterium uptake because the analyte peak shifts by one mass unit for each deuterium incorporated (for ϩ1 charge state). H/D exchange with D 2 O or CD 3 OD as the exchange reagent is commonly accepted to proceed via the relay mechanism [54,55]. In this mechanism, the exchange reagent forms a complex with the peptide and a proton is transferred to the exchange reagent while a deuteron is transferred to a separate site on the peptide.…”

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confidence: 99%

Computational investigation and hydrogen/deuterium exchange of the fixed charge derivative tris(2,4,6-Trimethoxyphenyl) phosphonium: Implications for the aspartic acid cleavage mechanism

Herrmann

Wysocki

Vorpagel

2005

J. Am. Soc. Mass Spectrom.

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Aspartic acid (Asp)-containing peptides with the fixed charge derivative tris(2,4,6-trimethoxyphenyl) phosphonium (tTMP-P ϩ ) were explored computationally and experimentally by hydrogen/deuterium (H/D) exchange and by fragmentation studies to probe the phenomenon of selective cleavage C-terminal to Asp in the absence of a "mobile" proton. Ab initio modeling of the tTMP-P ϩ electrostatic potential shows that the positive charge is distributed on the phosphonium group and therefore is not initiating or directing fragmentation as would a "mobile" proton. Geometry optimizations and vibrational analyses of different Asp conformations show that the Asp structure with a hydrogen bond between the side-chain hydroxy and backbone carbonyl lies 2.8 kcal/mol above the lowest energy conformer. In reactions with D 2 O, the phosphonium-derived doubly charged peptide (H ϩ )P ϩ LDIFSDF rapidly exchanges all 12 of its exchangeable hydrogens for deuterium and also displays a nonexchanging population. With no added proton, P ϩ LDIFSDF exchanges a maximum of 4 of 11 exchangeable hydrogens for deuterium. No exchange is observed when all acidic groups are converted to the corresponding methyl esters. Together, these H/D exchange results indicate that the acidic hydrogens are "mobile locally" because they are able to participate in exchange even in the absence of an added proton. Fragmentation of two distinct (H ϩ )P ϩ LDIFSDF ion populations shows that the nonexchanging population displays selective cleavage, whereas the exchanging population fragments more evenly across the peptide backbone. This result indicates that H/D exchange can sometimes distinguish between and provide a means of separation of different protonation motifs and that these protonation motifs can have an effect on the fragmentation. (J Am Soc Mass Spectrom 2005, 16, 1067-1080

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Gas-phase hydrogen/deuterium exchange as a molecular probe for the interaction of methanol and protonated peptides

Cited by 112 publications

References 30 publications

Fragmentation of doubly-protonated peptide ion populations labeled by H/D exchange with CD3OD

Fragmentation of doubly-protonated peptide ion populations labeled by H/D exchange with CD3OD

Observation of zwitterion formation in the gas-phase H/D-exchange with CH₃OD: Solution-phase structures in the gas phase

Computational investigation and hydrogen/deuterium exchange of the fixed charge derivative tris(2,4,6-Trimethoxyphenyl) phosphonium: Implications for the aspartic acid cleavage mechanism

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Gas-phase hydrogen/deuterium exchange as a molecular probe for the interaction of methanol and protonated peptides

Cited by 112 publications

References 30 publications

Fragmentation of doubly-protonated peptide ion populations labeled by H/D exchange with CD3OD

Fragmentation of doubly-protonated peptide ion populations labeled by H/D exchange with CD3OD

Observation of zwitterion formation in the gas-phase H/D-exchange with CH3OD: Solution-phase structures in the gas phase

Computational investigation and hydrogen/deuterium exchange of the fixed charge derivative tris(2,4,6-Trimethoxyphenyl) phosphonium: Implications for the aspartic acid cleavage mechanism

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Observation of zwitterion formation in the gas-phase H/D-exchange with CH₃OD: Solution-phase structures in the gas phase