Kevin Aart Douglass

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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(More)
BACKGROUND There is continued and significant debate regarding the salient etiologies associated with graft loss and racial disparities in kidney transplant recipients. METHODS This was a longitudinal cohort study of all adult kidney transplant recipients, comparing patients with early graft loss (<5 years) to those with graft longevity (surviving graft(More)
ion. It has also been postulated that compounds can undergo direct Penning ionization with excited plasma species such as helium metastable atoms. Different classes of analytes will preferentially ionize through different mechanisms. For instance, many polar analytes will produce spectra consisting of strictly protonated molecular ions, MH + , indicating(More)
Desorption electrospray ionization mass spectrometry (DESI-MS) requires little to no sample preparation and has been successfully applied to the study of biologically significant macromolecules such as proteins. However, DESI-MS and other ambient methods that use spray desorption to process samples during ionization appear limited to smaller proteins with(More)
A simple, manual method for predicting the highest intensity charge states (HICS) of denatured protein ions generated by electrospray ionization based on inspection of the proteins' amino acid sequence is proposed. The HICS is accurately predicted by identifying groupings of nearby basic amino acids in the positive mode or acidic amino acid residues in the(More)
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.(More)
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(More)
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