title: Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS3experiments.
abstract: Lipidomics calls for information on detected lipids and conjugates whose structural elucidation by mass spectrometry requires to rationalization of their gas phase dissociations toward collision-induced dissociation (CID) processes. This study focused on activated dissociations of two lipoamino acid (LAA) systems composed of N-palmitoyl acyl coupled with aspartic and glutamic acid mono ethyl esters (as LAA(*D)and LAA(*E)). Although in MS/MS, their CID spectra show similar trends, e.g., release of water and ethanol, the [(LAA(*D/*E)+H)-C2H5OH]+product ions dissociate via distinct pathways in sequential MS3experiments. The formation of all the product ions is rationalized by charge-promoted cleavages often involving stepwise processes with ion isomerization into ion-dipole prior to dissociation. The latter explains the maleic anhydride or ketene neutral losses from N-palmitoyl acyl aspartate and glutamate anhydride fragment ions, respectively. Consequently, protonated palmitoyl acid amide is generated from LAA(*D),whereas LAA(*E)leads to the [*E+H-H2O]+anhydride. The former releases ammonia to provide acylium, which gives the CnH(2n-1)and CnH(2n-3)carbenium series. This should offer structural information, e.g., to locate either unsaturation(s) or alkyl group branching present on the various fatty acyl moieties of lipo-aspartic acid in further studies based on MSnexperiments.
authors: IPCM UMR-CNRS 8232, University Paris VI (UPMC), Paris, France.|Université Oran 1 Ahmed Ben-Balla, Oran, Algeria.|MetaToul-Lipidomic, MetaboHUB, I2MC INSERM U1048, Toulouse, France.
authors: Toufik Taalibi
authors: TT
authors: Boukerche
authors: IPCM UMR-CNRS 8232, University Paris VI (UPMC), Paris, France.
authors: Sandra
authors: S
authors: Alves
authors: MetaToul-Lipidomic, MetaboHUB, I2MC INSERM U1048, Toulouse, France.
authors: Pauline
authors: P
authors: Le Faouder
authors: IPCM UMR-CNRS 8232, University Paris VI (UPMC), Paris, France.|CEA, iBiTec-S, SPI, LEMM, MetaboHUB, Gif Sur Yvette, France.
authors: Anna
authors: A
authors: Warnet
authors: MetaToul-Lipidomic, MetaboHUB, I2MC INSERM U1048, Toulouse, France.
authors: Justine
authors: J
authors: Bertrand-Michel
authors: LCOMM Université de Mustafa Stambouli, Mascara, Algeria.
authors: Mohamed
authors: M
authors: Bouchekara
authors: Université Oran 1 Ahmed Ben-Balla, Oran, Algeria.
authors: Mohammed
authors: M
authors: Belbachir
authors: IPCM UMR-CNRS 8232, University Paris VI (UPMC), Paris, France. jean-claude.tabet@courriel.upmc.fr.|CEA, iBiTec-S, SPI, LEMM, MetaboHUB, Gif Sur Yvette, France. jean-claude.tabet@courriel.upmc.fr.
authors: Jean-Claude
authors: JC
authors: Tabet
mesh_terms: D000812:Anhydrides; D001224:Aspartic Acid / Q000737:chemistry*; D005019:Ethyl Ethers / Q000737:chemistry; D018698:Glutamic Acid / Q000031:analogs & derivatives / Q000737:chemistry*; D006865:Hydrogenation; D007477:Ions / Q000737:chemistry; D008055:Lipids / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D014867:Water / Q000737:chemistry
chemical_list: D000812:Anhydrides; D005019:Ethyl Ethers; D007477:Ions; D008055:Lipids; C528491:glutamate anhydride; D014867:Water; D001224:Aspartic Acid; D018698:Glutamic Acid
keywords: ESI/MS n; Ion–dipole; N-fatty-acyl amino-acid; Regioselectivity