P 130 - Oxidative metabolism of phosphatidylethanolamines predicted by electrochemistry-mass spectrometry

Abstract

Phosphatidylethanolamines (PEs) are a major class of phospholipids in cellular membranes and lipoproteins. Oxidation of PEs generates products exerting a vast number of biological functions, not totally unveiled yet. In vitro biomimetic models have been used to identify oxidized PEs and to develop analytical strategies for their targeted in vivo detection. Most models are based on radical oxidation, but the oxidative metabolism of PE also relies on controlled reactions catalyzed by enzymes as lipoxygenase (LOX), which can be mimicked by electrochemical (EC) oxidation. In this study, three PE standards were oxidized using an EC flow-through cell as a biomimetic model of oxidative injury. The oxidation products were identified by on-line EC-electrospray ionization mass spectrometry (ESI-MS and MS/MS). Long chain and short chain oxidation products were identified as modifications in the sn-2 acyl chain, whereas the oxidation pattern was dependent on the unsaturation level. Some of these oxidized species have already been observed during the modification of PEs driven by radical oxygen species (ROS), and among these products it was possible to characterize the oxidized isomers synthesized by 15-LOX in human immune cells. This EC-MS platform was, therefore, able to mimic the oxidative metabolism of PEs mediated by both ROS and enzymes.