title: Evaluation of oxidation and glyco-oxidation of 1-palmitoyl-2-arachidonoyl-phosphatidylserine by LC-MS/MS.
abstract: Phosphatidylserine (PS) is an aminophospholipid found mainly in the plasma membranes of all mammalians cells, playing important roles in biological processes such as apoptosis and cell signaling. Due to the presence of a free amine group, under hyperglycemic conditions, PS can undergo glycation reaction, which may increase the susceptibility to oxidation. However, far too little attention has been paid to glycation and oxidation of PS. In this work we studied the oxidation, glycation and glyco-oxidation of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phospho-l-serine (PAPS). PAPS and glycated PAPS were oxidized through a Fenton reaction and the oxidation products were monitored by ESI-MS in negative mode. Also, we developed a new sensitive liquid chromatography method coupled with tandem mass spectrometry (LC-MS/MS) to provide a complete profile of oxidized and glyco-oxidized PS. We were able to separate and identify several oxidation products of PAPS and glycated PAPS with modifications in unsaturated fatty acyl chain as long chain oxidation product (hydroxy and mono to tetra-hydroperoxy derivatives), and short chain products with a shortened fatty acyl chain with C5 and C8 length and aldehyde or carboxylic terminal. We have also observed oxidation products arising from structural changes in the serine polar head, which lead to oxidation products with an acetic acid terminal (glycerophosphoacetic acid derivatives) and lysoPS species. Oxidation of glycated PAPS gave rise to several products involving oxidative cleavages of the glucose moiety, mainly between C1 and C2 of the sugar unit. These oxidation products with different polar head groups have shown distinct neutral loss fragmentation patterns. Simultaneous oxidative modifications of the polar head and the fatty acyl chains were also observed. The findings from this study contribute to an ongoing effort to detect PS oxidation and glyco-oxidation products in biological systems.
authors.affiliation: Mass Spectrometry Centre, QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Maciel
authors.forename: Renata
authors.initials: R
authors.lastname: Faria
authors.forename: Deolinda
authors.initials: D
authors.lastname: Santinha
authors.forename: M Rosário M
authors.initials: MR
authors.lastname: Domingues
authors.forename: Pedro
authors.initials: P
authors.lastname: Domingues
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D006031:Glycosylation; D010084:Oxidation-Reduction; D010718:Phosphatidylserines / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D010718:Phosphatidylserines