Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS3 experiments
Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS3 experiments
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DOI：
10.1007/s00726-016-2286-0
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发表时间：
2016-12-01
期刊：
影响因子：
3.5
通讯作者：
Tabet, Jean-Claude
中科院分区：
文献类型：
--
作者：
Boukerche, Toufik Taalibi;Alves, Sandra;Tabet, Jean-Claude
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 MS3 experiments. 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 C (n) H(2n-1) and C (n) H(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 MS (n) experiments.
