17th International Mass Spectrometry Conference :: Prague, 2006
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|Presentation date:||Mon, Aug 28, 2006|
|Presentation time:||14:30 – 16:00|
Rosa Viner1, Vladimir Tyurin2, Andrew Amoscato2, Hulya Bayir2, Patrick Kochanek2, Ken Miller1, Valerian E. Kogan21 Thermo Electron Corporation, San Jose, United States
Correspondence address: Rosa Viner, Thermo Electron Corporation, 355 River Oaks Parkway, San Jose, 95134 United States.
Keywords: MALDI; MS/MS, Structure Determination; Oxidation; Phospholipids.
Novel aspect: Chracteization of phospholipid peroxidation products by MALDI MS.
Apoptosis is the major contributor to acute brain injury as well as neurodegenerative diseases. Two anionic phospholipids – cardiolipin (CL) in mitochondria and phosphatidylserine (PS) in plasma membrane – have recently been shown to undergo peroxidative metabolism and participate in execution of apoptotic program and act as signaling molecules. Therefore, structural characterization of different molecular species of CL and PS and their oxidation products is essential. Using the FinniganTM LTQTM and LTQTM Orbitrap hybrid mass spectrometer with vMALDITM source we performed analysis of different molecular species of CL and PS isolated by 2D-HPLC of lipid extracts acquired from mitochondrial/synaptosomal fractions of normal rat brain with those obtained from animals exposed to Controlled Cortical Impact (CCI). The high resolution and accuracy of full MS spectra combined with low-energy MSn-spectra of the [M-H]– or [M+H]+ ions provide complete identification and structural information for PS and CL characterization. We found that CLs are represented by a rich spectrum of at least 12 different molecular species containing a variety of fatty acid residues (from C14:0 to C22:6). Importantly, significant content of polyunsaturated molecular species of CL makes them susceptible to peroxidation. Several modified species of CL were identified. In addition, accumulation of oxidized and monolyso-CL species, containing primarily fatty acid residue C22:5 was detected in CCI samples. In contrast to CL, PS displayed a relatively uniform pattern of molecular species with one dominating form – C16:0, C22:6. Notably, brain trauma caused significant oxidation of this PS species. MS analysis revealed the formation of several oxygenation products (+OOH, +2OOH). Thus, our results have shown that phospholipid peroxidation products can be successfully detected and characterized in brain tissue by MALDI MS analysis. Further work will establish the variety and contribution of these products in regulation of apoptotic signaling.