Ion mobility spectrometry (IMS) coupled to mass spectrometry (MS) has become a powerful analytical tool in a number of chemical areas, from probing the gas-phase structures of native proteins and protein complexes, to the analysis of complex mixtures of peptides. The work presented here aims to incorporate chemical reactions prior to or during IMS experiments to either increase analytical capabilites (e.g. improved sensitivity, peak capacity, or confidence of assignment) or to provide additional, complementary information in a given analysis.
The first set of experiments focuses on the use of 18-crown-6 (18C6) ether as an electrospray solution additive to generate noncovalent complexes with tryptic peptide ions. Ions can be analyzed in one-dimensional IMS as complexes, or in IMS-IMS separations; the latter experiment utilizing the difference in mobility of ions in their complexed and “naked” forms. Loss of 18C6 adducts causes shifts in mobility greater than observed between different conformations of peptides and doubles the total peak capacity of IMS-IMS separations.
A second set of experiments focuses on gas-phase reactivity of protein ions. Exposure of [M+11H]11+ ions of ubiquitin to D2O vapor reveals a millisecond timescale structural transition which occurs spontaneously at 300 K. The results of these experiments has provided insights to interpret the differences observed in hydrogen/deuterium exchange measurements across different laboratories and instruments.
Lastly, results are reported for a small tripeptide library designed to generate ion mobility shift reagents for saccharide analysis. Truncated sequences that mimic the nonadjacent residues of a recognition protein’s binding cleft appear to retain sufficient affinity as to be analytical useful. Examination of disaccharide isomers suggests that complex formation is sensitive to both the sequence of the peptide reagent and to saccharide structure (both linkage- and ring-type).
|Advisor:||Clemmer, David E.|
|Commitee:||Dragnea, Bogdan, Jacobson, Stephen C., Jarrold, Martin F.|
|School Location:||United States -- Indiana|
|Source:||DAI-B 72/10, Dissertation Abstracts International|
|Subjects:||Analytical chemistry, Biochemistry|
|Keywords:||Gas-phase structures, Ion mobility spectrometry, Isotopic exchange, Mass spectrometry, Native proteins, Noncovalent complexes, Peptides|
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