Coupling Electrospray Corona Discharge and Ion Mobility Mass Spectrometry: from Peptides

Coupling Electrospray Corona Discharge and Ion Mobility Mass Spectrometry: From Peptides to Large Macromolecular Protein Complexes

Supporting Information

Iain D. G. Campuzano and Paul D. Schnier

Amgen, Department of Molecular Structure and Characterization, Thousand Oaks, CA, 91320, USA

Running title: Electrospray Corona Discharge: An Effective Method for Manipulating an Ion’s Charge

Corresponding author: Iain Campuzano, ; 805-313-5313

Figure S1. A computer aided design representation of the corona discharge probe (upper) and its orientation on the Waters nESI Z-Spray ion source (lower).

Figure S2. TWIM calibration curves used to generate ΩHe values for the charged reduced and non-charge reduced native pyruvate kinase complex. TWIM speeds were 190, 195 and 200 m/s. TWIM amplitude was ramped from 3-8 V. Drift-time (x-axis) measured in ms. The 190 m/s calibration curve has been labelled with the proteins and charge states used for calibration.

Figure S3. A comparison of the +2 charge state of ubiquitin produced by corona-discharge using medical grade air (upper spectrum) and N2 (lower spectrum).

Figure S4. Singly charged Glu-fibrinopeptide b isotope distribution produced upon corona discharge (-6000 V). The m/z value is consistent with [M+H]+ species and not the charge reduced radical cation species [M+2H]+•.

Figure S5. A comparison of the total ion current of a PEG10K infusion obtained with corona discharge on and off. The intensities of both chromatograms are linked via the vertical axis.

Figure S6. A comparison of mass spectra of native pyruvate kinase corona discharge activated (upper trace) and corona discharge deactivated (lower trace).

Figure S7. A comparison of TWIM arrival-time-distributions of pyruvate kinase charge states +35, +34, +33 and +32 with corona discharge activated and deactivated. ΩHe and σ values were derived from three TWIM measurements made at 3 different velocities; 190, 195 and 200 m/s. The TWIM amplitude was operated as a ramp 3-8 V. ATDs displayed from 190 m/s TWIM acquisition.

Table S1. Observed charge states and m/z values for all native protein complexes studied upon corona discharge activation.

Table S2. Native pyruvate kinase charge states (z), helium (ΩHe) collision cross-section values (Å2) produced up corona discharge. Standard deviation values (σ) are also reported as Å2 and were derived from three TWIM measurements made at 3 different TWIM velocities; 190, 195 and 200 m/s. The TWIM amplitude was operated as a ramp 3-8 V. ΩHe and σ values for charge states 23 to 14 are not displayed since they do not fall within the TWIM calibration range.

Table S3. TWIM derived ΩHe values for native pyruvate kinase (no charge reduction) and a comparison to RF-confining drift-tube derived values1. σ value (Å2) based on 3 TWIM measurements acquired at different TWIM velocities; 190, 195 and 200 m/s. The TWIM amplitude was operated as a ramp 3-8 V.

1. Bush, M. F.; Hall, Z.; Giles, K.; Hoyes, J.; Robinson, C. V.; Ruotolo, B. T. Anal. Chem. 2010, 82, 9557-9565.