LAUSR

Oxidative stress has been linked to several inflammatory diseases; this may be due to oxidative damage to biomolecules. Oxidized phospholipids have been shown to be related to several pathophysiological pathways, as antigens or ligands, and more recently through protein modification creating protein-phospholipid adducts. The literature on protein-phospholipid adducts is sparse, although this type of protein modification could be of interest as potential biomarkers for disease. The aim of this project is to study the formation of these adducts, using both intact protein and bottom-up mass spectrometry techniques. For this work, two model proteins were modified with pentanal, a saturated breakdown product of phospholipid oxidation and a model for phospholipid aldehydes, and the adducts stabilized by reduction and analysed by ESI MS. The modified proteins were also subjected to SDS-PAGE, in-gel tryptic digestion, and LC-MSMS analysis. The results of the top-down and bottom-up analysis show the presence of pentanal adducts, and identified the sequence of the modified peptides. The mass shifts observed were consistent with the formation of Schiff's base adducts, and only modifications to lysine were observed. Product ions that might be useful as diagnostic ions for the modification were identified. Future work will investigate adduct formation using oxidized phospholipids.