- Stagliano, Michael C.
- Graduate Program:
- Doctor of Philosophy
- Document Type:
- Date of Defense:
- September 07, 2010
- Committee Members:
- Mark Maroncelli, Dissertation Advisor/Co-Advisor
Mark Maroncelli, Committee Chair/Co-Chair
Alan James Benesi, Committee Member
James Bernhard Anderson, Committee Member
Douglas D Archibald, Committee Member
A Daniel Jones, Committee Member
- Lipid Fragmentation
- As recognition of the importance of the role of lipids in human biology, chemical signaling, and plant defense mechanisms becomes more prevalent, new rapid methods for identification, detection, and quantification are needed. Chapter 2 reports a new method for filtering mass spectrometric data using the percent hydrogen of a compound. To demonstrate the utility of the data filter, it was used to accelerate bioactive compound discovery by directing biological assays toward anticipated neutral lipids. Through the use of accurate mass measurements from time-of-flight (TOF) mass spectrometry (MS) and fragment ion masses generated using nonselective collision-induced dissociation (CID), a previously unknown lipid activator of constitutive androstane receptor 2 (CAR2) was identified as di(2-ethylhexyl) phthalate (DEHP). Chapter 3 advances the ability of mass spectrometry to selectively detect isomers, using a rapid ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for distinguishing two dioctyl phthalate esters, di(2-ethylhexyl) phthalate and di-n-octyl phthalate (DNOP). Elution of the lipid standards is achieved in a 5 minute chromatography run and multiple reaction monitoring (MRM) tandem mass spectrometry methods yield data for quantification. In Chapter 4, a MS/MS method is developed upon existing technologies to determine the relative ratios of isomeric phosphatidylethanolamine (PE) lipids in Arabidopsis thaliana extracts. After demonstrating the ability of the method to distinguish between isomers, the fragmentation behavior of PE lipids was investigated. Commercially available PE standards, along with custom, in-house synthetic standards were subjected to collision-induced dissociation at various collision cell potentials to determine the effects of double bonds and head group modification on sn-1 compared to sn-2 position fragmentation. Results indicate that PE lipid fragmentation can be directed by both of the aforementioned modifications, resulting in a shift from sn-1 to sn-2 position fragmentation and formation of the corresponding fatty acid ion. The methods described in this dissertation serve to decrease the complexity of mass spectral data sets, increase the ability to discover and quantify novel small molecule metabolites, and enhance the understanding of lipid fragmentation behavior.