Publications by authors named "K James Durbin"
Individual ion mass spectrometry (IMS) is the Orbitrap-based extension of the niche mass spectrometry technique known as charge detection mass spectrometry (CDMS). While traditional CDMS analysis is performed on in-house-built instruments such as the electrostatic linear ion trap, IMS extends CDMS analysis to Orbitrap analyzers, allowing charge detection analysis to be available to the scientific community at large. IMS simultaneously measures the mass-to-charge ratios (m/z) and charges (z) of hundreds to thousands of individual ions within one acquisition event, creating a spectral output directly into the mass domain without the need for further spectral deconvolution.
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- Antibody-drug conjugates (ADCs) are a new type of treatment that merge the effectiveness of toxic drugs with the precision of antibodies, but their complex structure makes analysis challenging.
- The use of middle-down mass spectrometry (MD MS) faces issues with spectral congestion, which can hide important fragment ions that reveal drug attachment sites.
- Proton transfer charge reduction (PTCR) is introduced to simplify these spectra, allowing for a more effective investigation of ADCs and improving the identification of drug localization compared to traditional methods.
Improving Top-Down Sequence Coverage with Targeted Fragment Matching.
J Am Soc Mass Spectrom
December 2024
Top-down mass spectrometry (TDMS) of intact proteins and antibodies enables direct determination of truncations, sequence variants, post-translational modifications, and disulfides without the need for any proteolytic cleavage. While mass deconvolution of top-down tandem mass spectra is typically used to identify fragment masses for matching to candidate proteoforms, larger molecules such as monoclonal antibodies can produce many fragment ions, making spectral interpretation challenging. Here, we explore an alternative approach for proteoform spectral matching that is better suited for larger protein analysis.
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- Overexpression of BCL-X, an antiapoptotic protein, leads to drug resistance and disease progression in various cancers, making it an attractive target for selective inhibitors.
- Initial selective BCL-X inhibitors were effective in preclinical models but caused serious cardiovascular toxicity in higher species, prompting the development of safer alternatives using antibody-drug conjugates.
- The antibody-drug conjugate AM1-15 showed promise by inhibiting tumor growth without causing cardiovascular issues, though it did present other toxicities that were addressed in the modified AM1-AAA, which is now part of the first clinical trial for a selective BCL-X-targeting drug.
Modern mass spectrometry technology allows for extensive sequencing of the ~ 25 kDa subunits of monoclonal antibodies (mAbs) produced by IdeS proteolysis followed by disulfide bond reduction, an approach known as middle-down mass spectrometry (MD MS). However, the spectral congestion of tandem mass spectra of large polypeptides dramatically complicates fragment ion assignment. Here, we report the development and benchmark of an MD MS strategy based on the combination of different ion fragmentation techniques with proton transfer charge reduction (PTCR) to simplify the gas-phase sequencing of mAb subunits.
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