Publications by authors named "Kevin A Douglass"
On the role of a direct interaction between protein ions and solvent additives during protein supercharging by electrospray ionization mass spectrometry.
Eur J Mass Spectrom (Chichester)
October 2015
The addition of certain reagents during the electrospray ionization mass spectrometry of proteins can shift the protein ion signal charge-state distributions (CSDs) to higher average charge states, a phenomenon known as 'supercharging'. The role of reagent gas-phase basicity (GB) during this process was investigated in both the negative and positive ion modes. Reagents with known or calculated GBs were added individually in equimolar amounts to protein solutions which were subsequently electrosprayed for mass spectrometry analysis.
View Article and Find Full Text PDFArticle Synopsis
- A new manual method is proposed for predicting the highest intensity charge states (HICS) of denatured proteins generated by electrospray ionization, focused on the proteins' amino acid sequences.
- This method identifies groupings of basic or acidic amino acids to assess the likelihood of charge states, noting that at least three noncharged residues should separate charged amino acids for optimal prediction.
- The approach is cost-effective and can yield predictions closely aligned with experimental data, although it may fall short for some proteins due to factors like the disulfide bond conformational inflexibility.
Article Synopsis
- DESI-MS is a method that simplifies sample preparation and has been effective for analyzing macromolecules like proteins, but it struggles with larger proteins over 25 kDa.
- The study explores why larger proteins (up to 66 kDa) show decreased sensitivity in DESI-MS, finding that issues like incomplete dissolution and clustering of proteins can hinder their detection.
- Alternatives to traditional spray desorption methods are suggested to improve protein analysis, addressing the limitations identified in the study.
Spray desorption collection (SDC) and reflective electrospray ionization (RESI) were used to independently study the desorption and ionization processes that together comprise desorption electrospray ionization (DESI). Both processes depend on several instrumental parameters, including the nebulizing gas flow rate, applied potential, and source geometries. Each of these parameters was optimized for desorption, as represented by the results obtained by SDC, and ionization, as represented by the results obtained by RESI.
View Article and Find Full Text PDFInvestigating the role of adducts in protein supercharging with sulfolane.
J Am Soc Mass Spectrom
March 2012
The supercharging effect of sulfolane on cytochrome c (cyt c) during electrospray ionization mass spectrometry (ESI-MS) in the absence of conformational effects was investigated. The addition of sulfolane on the order of 1 mM or greater to denaturing solutions of cyt c results in supercharging independent of protein concentration over the range of 0.1 to 10 μM.
View Article and Find Full Text PDF