Work

Digital Ion Trap Isolation and Mass Analysis of Macromolecular Analytes with Multiply Charged Ion Attachment

Year: 2024

Type: article

Abstract: Multiply charged ions produced by electrospray ionization (ESI) of heterogeneous mixtures of macromolecular analytes under native conditions are typically confined to relatively narrow ranges of mass-to-charge ( m / z ) ratio, often with extensive overlap. This scenario makes charge and mass assignments extremely challenging, particularly when individual charge states are unresolved. An ion/ion reaction strategy involving multiply charged ion attachment (MIA) to the mixture components in a narrow range of m / z can facilitate charge and mass assignment. In MIA operation, multiply charged reagent ions are attached to the analyte ions of opposite polarity to provide large m / z displacements resulting from both large changes in mass and charge. However, charge reduction of the high m / z ions initially generated under native ESI conditions requires the ability to isolate high m / z ions and to analyze even higher m / z product ions. Digital ion trap (DIT) operation offers means for both high m / z ion isolation and high m / z mass analysis, in addition to providing conditions for the reaction of oppositely charged ions. The feasibility of conducting MIA experiments in a DIT that takes advantage of high m / z ion operation is demonstrated here using a tandem 2D-3D DIT instrument. Proof-of-concept MIA experiments with cations derived from β-galactosidase using the 20– charge state of human serum immunoglobulin G (IgG, ∼149 kDa) as the reagent anion are described. MIA experiments involving mixtures of ions derived from the E. coli. ribosome are also described. For example, three components in a mixture of 70S particles (>2.2 MDa) were resolved and assigned with masses and charges following an MIA experiment involving the 20– charge state of human serum IgG.

Source: Journal of the American Society for Mass Spectrometry

DOI: 10.1021/jasms.4c00292

Authors: Liangxuan Fu, Nicholas R. Ellin, Nicolas J. Pizzala, Erick G. Baez Bolivar, Scott A. McLuckey

Institution: Purdue University West Lafayette

Language: English

Topic: Mass Spectrometry Techniques and Applications

Subfield: Spectroscopy

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funders: National Institutes of Health, National Institute of General Medical Sciences

Awards: G1443944208, G1801581537, Gas-phase Bio-conjugation in the Tandem Mass Spectrometry of Peptides Proteins