Collision Cross Sections of Proteins and Their Complexes: A Calibration Framework and Database for Gas-Phase Structural Biology

Bush, Matthew F.; Hall, Zoe; Giles, Kevin; Hoyes, John; Robinson, Carol V.; Ruotolo, Brandon T.

doi:10.1021/ac1022953

Cited by 712 publications

(1,171 citation statements)

References 42 publications

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“…Reference 1 based this conversion on Millikan's drag law for spheres in free molecule flow. Although unusual in protein studies, this assumption agrees well with other calculation methods [1,8,9]. Further qualitative support on the general issue of protein deformation upon electrospraying follows directly from Figure 1.…”

Section: Protein Deformation Upon Electrosprayingsupporting

confidence: 83%

Why do GroEL Ions Exhibit Two Gas Phase Conformers?

Mora

2012

J. Am. Soc. Mass Spectrom.

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The reasons for the existence of two gas phase conformers for electrosprayed ions of the large tetradecameric protein complex GroEL are considered. Key features are that: (1) both conformers extrapolate to very similar cross sections in the limit of zero charge; (2) both conformers supercharge above the maximum value permitted by the Rayleigh criterion; and (3) one of the conformers supercharges substantially more than the other. We hypothesize that the supercharging observed is associated to the approximately cylindrical shape of GroEL in aqueous solution, enabling accumulation of extra charge on either one or two of its bases when they intersect the evaporating drop surface. The two conformers would then correspond to cases when either one or the two bases of the cylinder carry extra charge. Apparently, the conformer symmetrically (doubly) supercharged on both ends is Coulombically stretched, therefore exhibiting a mobility different from the conformer asymmetrically supercharged only on one end. Several general consequences follow. First, non-spherical proteins may generally be charged above the usual Rayleigh limit. Second, we confirm the previously advanced but contentious notion that gas phase protein ions are readily compacted or stretched away from their crystal structure by capillary and Coulombic forces during the electrospraying process.

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Section: Protein Deformation Upon Electrosprayingsupporting

confidence: 83%

Why do GroEL Ions Exhibit Two Gas Phase Conformers?

Mora

2012

J. Am. Soc. Mass Spectrom.

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“…The charge states of ADH generated by native ESI (23+ to 26+) were used to calibrate the spectrum and CCS values were calculated using a logarithmic fit as described by Ruotolo and colleagues [49,50] …”

Section: Resultsmentioning

confidence: 99%

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

J. Am. Soc. Mass Spectrom.

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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.

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“…This relationship is used to determine K i and reduced mobilities, K 0,i , of C2-C8 and C12 anion-coordinated multimer species (see SI). Ω i of BK +1 , BK +2 , AT2 +1 , AT2 +2 , UB +7 , and UB +8 from [8,9] were used for mobility calibration of the ROMIAC. A linear relationship exists between φ * i and K −1 i , and…”

Section: Calibration Proceduresmentioning

confidence: 99%

“…Collisional cross-section values of BK +1 , BK +2 , AT2 +1 , AT2 +2 , UB +7 , and UB +8 from [8,9] were used in the mobility calibration of the ROMIAC. There is a linear relationship between φ * i and…”

Section: Calculations Reduced Mobility and Collisional Cross-sectionmentioning

confidence: 99%

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Ion Mobility-Mass Spectrometry with a Radial Opposed Migration Ion and Aerosol Classifier (ROMIAC)

et al. 2013

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The first application of a novel differential mobility analyzer, the radial opposed migration ion and aerosol classifier (ROMIAC), is demonstrated. The ROMIAC uses antiparallel forces from an electric field and a cross-flow gas to both scan ion mobilities and continuously transmit target mobility ions with 100% duty cycle. In the ROMIAC, diffusive losses are minimized, and resolution of ions, with collisional cross-sections of 200–2000 Å2, is achieved near the nondispersive resolution of ∼20. Higher resolution is theoretically possible with greater cross-flow rates. The ROMIAC was coupled to a linear trap quadrupole mass spectrometer and used to classify electrosprayed C2–C12 tetra-alkyl ammonium ions, bradykinin, angiotensin I, angiotensin II, bovine ubiquitin, and two pairs of model peptide isomers. Instrument and mobility calibrations of the ROMIAC show that it exhibits linear responses to changes in electrode potential, making the ROMIAC suitable for mobility and cross-section measurements. The high resolution of the ROMIAC facilitates separation of isobaric isomeric peptides. Monitoring distinct dissociation pathways associated with peptide isomers fully resolves overlapping peaks in the ion mobility data. The ability of the ROMIAC to operate at atmospheric pressure and serve as a front-end analyzer to continuously transmit ions with a particular mobility facilitates extensive studies of target molecules using a variety of mass spectrometric methods.

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Collision Cross Sections of Proteins and Their Complexes: A Calibration Framework and Database for Gas-Phase Structural Biology

Cited by 712 publications

References 42 publications

Why do GroEL Ions Exhibit Two Gas Phase Conformers?

Why do GroEL Ions Exhibit Two Gas Phase Conformers?

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

Ion Mobility-Mass Spectrometry with a Radial Opposed Migration Ion and Aerosol Classifier (ROMIAC)

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