title: Gas-phase transformation of phosphatidylcholine cations to structurally informative anions via ion/ion chemistry.
abstract: Gas-phase transformation of synthetic phosphatidylcholine (PC) monocations to structurally informative anions is demonstrated via ion/ion reactions with doubly deprotonated 1,4-phenylenedipropionic acid (PDPA). Two synthetic PC isomers, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (PC(16:0/18:1)) and 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine (PC(18:1/16:0)), were subjected to this ion/ion chemistry. The product of the ion/ion reaction is a negatively charged complex, [PC + PDPA - H](-). Collisional activation of the long-lived complex causes transfer of a proton and methyl cation to PDPA, generating [PC - CH3](-). Subsequent collisional activation of the demethylated PC anions produces abundant fatty acid carboxylate anions and low-abundance acyl neutral losses as free acids and ketenes. Product ion spectra of [PC - CH3](-) suggest favorable cleavage at the sn-2 position over the sn-1 due to distinct differences in the relative abundances. In contrast, collisional activation of PC cations is absent of abundant fatty acid chain-related product ions and typically indicates only the lipid class via formation of the phosphocholine cation. A solution phase method to produce the gas-phase adducted PC anion is also demonstrated. Product ion spectra derived from the solution phase method are similar to the results generated via ion/ion chemistry. This work demonstrates a gas-phase means to increase structural characterization of phosphatidylcholines via ion/ion chemistry.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States.
authors.forename: John R
authors.initials: JR
authors.lastname: Stutzman
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blanksby
authors.forename: Scott A
authors.initials: SA
authors.lastname: McLuckey
mesh_terms: D005740:Gases / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
chemical_list: D005740:Gases; D007477:Ions; D010713:Phosphatidylcholines; C034973:1-oleoyl-2-palmitoylphosphatidylcholine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine