期刊
JOURNAL OF MASS SPECTROMETRY
卷 48, 期 2, 页码 205-215出版社
WILEY-BLACKWELL
DOI: 10.1002/jms.3149
关键词
sulfoquinovosyldiacylglycerols; plant sulfolipids; tandem MS; collision-induced dissociation; spinach leaves; regiochemistry
资金
- Ministero dell'Universita, dell'Istruzione e della Ricerca, MIUR (Italy) [2009KW27KE_003]
- EU [2915/12]
A full characterization of sulfoquinovosyldiacylglycerols (SQDGs) in the lipid extract of spinach leaves has been achieved using liquid chromatography/electrospray ionization-linear quadrupole ion trap mass spectrometry (MS). Low-energy collision-induced dissociation tandem MS (MS/MS) of the deprotonated species [MH] was exploited for a detailed study of sulfolipid fragmentation. Losses of neutral fatty acids from the acyl side chains (i.e. [MHRCOOH]) were found to prevail over ketene losses ([MHR'CHCO]) or carboxylates of long-chain fatty acids ([RCOO]), as expected for gas-phase acidity of SQDG ions. A new concerted mechanism for RCOOH elimination, based on a charge-remote fragmentation, is proposed. The preferential loss of a fatty acids molecule from the sn-1 position (i.e. [MHR1COOH]) of the glycerol backbone, most likely due to kinetic control of the gas-phase fragmentation process, was exploited for the regiochemical assignment of the investigated sulfolipids. As a result, 24 SQDGs were detected and identified in the lipid extract of spinach leaves, their number and variety being unprecedented in the field of plant sulfolipids. Moreover, the prevailing presence of a palmitic acyl chain (16:0) on the glycerol sn-2 position of spinach SQDGs suggests a prokaryotic or chloroplastic path as the main route for their biosynthesis. Copyright (c) 2013 John Wiley & Sons, Ltd.
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