Biomolecule analysis through gas phase ion/ion reactions and dissociation in linear ion trap instruments
Abstract
Electrodynamic ion traps have been used as reaction vessels for ion/ion reactions between positively and negatively charged ions. Ion/ion reactions implemented in a linear ion trap (LIT) is of greater interest because LITs have significantly higher trapping capability and dynamic range than three-dimensional (3D) ion traps. These reactions are useful in the gas phase characterization of biomolecules. Another very informative analytical tool is gas phase dissociation, which can be employed in conjunction of ion/ion reactions for a variety of bio-analytical applications. This dissertation discusses a few studies involving the use of ion/ion reactions and gas phase dissociation of biomolecules, such as new method development and chemistry investigation, for qualitative and quantitative analysis of proteins/peptides. The first part of this dissertation introduces a beam-type post-ion/ion reaction collisional activation method implemented on a triple quadrupole/linear ion trap system. By choosing an appropriate acceleration potential, a major increase in electron transfer dissociation (CID) yields and in peptide sequence coverage can be achieved with minimum disturbance from the collision induced dissociation (CID) of precursor ions and other product ions. Ion trap collisional activation behaviors of ETD products (c- and z·-type ions) were examined and are described in the second part of this thesis. The third part will discuss another new method that was developed on a quadrupole/time-of-flight (QqTOF) instrument with an increased duty cycle to obtain structural information from both ETD and CID data of tryptic peptides obtained in one single scan. Following this, electron transfer ion/ion reactions of iTRAQ labeled tryptic peptides for the quantitative analysis of proteins/peptides are described. Another new method implemented on the QqTOF system is reported in the dissertation, which enhanced ETD performance of relatively low charge state of tryptic peptides (with and without posttranslational modifications) by tailored broad-band activation with an increased duty cycle. Finally, demonstration of selective covalent bond formation in the gas phase via ion/ion reactions and subsequent dissociation will be stated for the first time.
Degree
Ph.D.
Advisors
McLuckey, Purdue University.
Subject Area
Analytical chemistry
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