A systematic study on the effect of histidine position and fragment ion size on the formation of bn ions

Miladi, Mahsan; Zekavat, Behrooz; Munisamy, Sharon M.; Solouki, Touradj

doi:10.1016/j.ijms.2012.02.024

Cited by 13 publications

(10 citation statements)

References 45 publications

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“…For example, the peak width of the later AT profile (which is generated from the additive sum of three individual IM profiles, as discussed in detail below) is much broader than the early AT conformer (which corresponds to a single isomer). 76 …”

Section: Resultsmentioning

confidence: 99%

Determination of ion mobility collision cross sections for unresolved isomeric mixtures using tandem mass spectrometry and chemometric deconvolution

Harper

Neumann

Stow

et al. 2016

Analytica Chimica Acta

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Ion mobility (IM) is an important analytical technique for determining ion collision cross section (CCS) values in the gas-phase and gaining insight into molecular structures and conformations. However, limited instrument resolving powers for IM may restrict adequate characterization of conformationally similar ions, such as structural isomers, and reduce the accuracy of IM-based CCS calculations. Recently, we introduced an automated technique for extracting “pure” IM and collision-induced dissociation (CID) mass spectra of IM overlapping species using chemometric deconvolution of post-IM/CID mass spectrometry (MS) data [J. Am. Soc. Mass Spectrom., 2014, 25, 1810–1819]. Here we extend those capabilities to demonstrate how extracted IM profiles can be used to calculate accurate CCS values of peptide isomer ions which are not fully resolved by IM. We show that CCS values obtained from deconvoluted IM spectra match with CCS values measured from the individually analyzed corresponding peptides on uniform field IM instrumentation. We introduce an approach that utilizes experimentally determined IM arrival time (AT) “shift factors” to compensate for ion acceleration variations during post-IM/CID and significantly improve the accuracy of the calculated CCS values. Also, we discuss details of this IM deconvolution approach and compare empirical CCS values from traveling wave (TW)IM-MS and drift tube (DT)IM-MS with theoretically calculated CCS values using the projected superposition approximation (PSA). For example, experimentally measured deconvoluted TWIM-MS mean CCS values for doubly-protonated RYGGFM, RMFGYG, MFRYGG, and FRMYGG peptide isomers were 288.8 Å2, 295.1 Å2, 296.8 Å2, and 300.1 Å2; all four of these CCS values were within 1.5% of independently measured DTIM-MS values.

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Section: Resultsmentioning

confidence: 99%

Determination of ion mobility collision cross sections for unresolved isomeric mixtures using tandem mass spectrometry and chemometric deconvolution

Harper

Neumann

Stow

et al. 2016

Analytica Chimica Acta

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“…"Raw data" peak width measurement is included in the software to emulate manual measurement of peak widths for comparison purposes. "Gaussian fitted" first fits the mobility data to a Gaussian distribution, such as previously reported [44], and returns two values, µ (i.e., peak centroid or AT) and σ (i.e., standard deviation), where σ is subsequently used to calculate the FWHH using equation 1 [50]:…”

Section: Im_fit Graphical User Interfacementioning

confidence: 99%

“…Although each of the aforementioned techniques can facilitate characterization of IMunresolved species (i.e., ions with similar CCSs), most approaches [37,[39][40][41][42][43] require isolation and subsequent fragmentation of ions at m/z values that are suspected to correspond to multiple IM-unresolved components. Previously, we showed that plots of IM profiles' full widths at halfheights (FWHHs) vs IM arrival times (ATs) could be used to determine peak purity [44]. The original technique, however, was time consuming because FWHH and AT for each IM profile had to be manually measured and plotted, therefore reducing the method's utility for highthroughput analysis.…”

Section: Introductionmentioning

confidence: 99%

Automated peak width measurements for targeted analysis of ion mobility unresolved species

Brantley

Pettit

Harper

et al. 2016

Analytica Chimica Acta

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Peak broadening in ion mobility (IM) is a relatively predictable process and abnormally broad peaks can be indicative of the presence of unresolved species. Here, we introduce a new ion mobility peak fitting (IM_FIT) software package for automated and systematic determination of traveling wave ion mobility (TWIM) unresolved species. To identify IM unresolved species, the IM_FIT software generates a trend line by plotting ions' mobility peak widths as a function of their arrival times. Utilizing user-defined thresholds, IM_FIT allows for automated and rapid detection of ions that deviate from the peak width trend line. To demonstrate the advantages of IM_FIT for automated detection of IM unresolved species, IM-mass spectrometry (IM-MS) data from a sample mixture containing polypropylene glycol and multiple peptides were analyzed. A total of 14 out of the 34 observed singly-charged IM peaks above 5% relative abundance (i.e., signal-to-noise ratios above ∼200) were tagged as potentially co-eluting ions by IM_FIT. Subsequently, the 14 IM peaks tagged as potentially unresolved (presumably, peaks corresponding to co-eluting compounds), were further analyzed by automated IM deconvolution (AIMD), liquid chromatography-IM-MS (LC-IM-MS), and/or ultra-high resolution mass spectrometry. Using the aforementioned techniques, more than 85% of the tagged IM peaks (12 out of 14) were confirmed to contain co-eluting ions. As an additional new finding, IM_FIT facilitated the discovery of an unexpected sequence-scrambled y-type fragment ion.

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“…In ESI experiments, ions were generated using an Analytica ESI source (Analytica of Branford, Inc., Branford, CT, USA) equipped with an in‐house‐built spraying setup . The ion spray was generated by applying ~4 kV (with respect to ground) on the stainless steel needle of a 100‐μL SGE syringe (SGE Inc., Austin, TX, USA).…”

Section: Experimental and Theoreticalmentioning

confidence: 99%

Efficient injection of low-mass ions into high magnetic field Fourier transform ion cyclotron resonance mass spectrometers

Zekavat

Szulejko

LaBrecque

et al. 2013

Rapid Commun. Mass Spectrom.

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A systematic study on the effect of histidine position and fragment ion size on the formation of bn ions

Cited by 13 publications

References 45 publications

Determination of ion mobility collision cross sections for unresolved isomeric mixtures using tandem mass spectrometry and chemometric deconvolution

Determination of ion mobility collision cross sections for unresolved isomeric mixtures using tandem mass spectrometry and chemometric deconvolution

Automated peak width measurements for targeted analysis of ion mobility unresolved species

Efficient injection of low-mass ions into high magnetic field Fourier transform ion cyclotron resonance mass spectrometers

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