Collision induced dissociation tandem mass spectrometry (CID-MS/MS) of glycolipids with special interest to sulfoquinovosyldiacylglycerols (SQDGs) (1,2) was employed for a detailed study of their fragmentation, clarifying some controversial aspects of previous investigations on these compounds. Losses of neutral fatty acids from the acyl side chains (i.e. [M−H−RxCOOH]−, x =1,2) were found to prevail over ketene losses or generation of long-chain fatty acid (FA) anions [RxCOO]−, x =1,2). The chain length, degree of unsaturation and positional distribution of the FAs attached to the primary (sn1) and secondary (sn2) hydroxyl groups of the glycerol moiety were established for all SQDG species identified in a sample extract of spinach leaves. The systematically observed preferential loss of FAs from the sn1 position of the glycerol backbone was exploited for the regiochemical assignment of the investigated species (3). The prevailing presence of a 16:0 (i.e., palmitic) acyl chain on the glycerol sn2 position of SQDGs suggests a prokaryotic path as the main route for their biosynthesis in spinach leaves (4). We envision that the versatility of this CID MS/MS approach, with ability to establish the regiochemistry of the acyl chains of SQDGs, will enable the systematic investigation of photosynthetic plants, algae, cyanobacteria, purple sulfur and non-sulfur bacteria with broad implications within and beyond the realm of sulfolipids and their involvement in membrane structures and cell communication.
Tandem mass spectrometry of sulphur-containing glycolipids: a step forward towards the regiochemical assignment of fatty acid acyl chains
BIANCO, Giuliana;Filomena Lelario;CATALDI, Tommaso
2012-01-01
Abstract
Collision induced dissociation tandem mass spectrometry (CID-MS/MS) of glycolipids with special interest to sulfoquinovosyldiacylglycerols (SQDGs) (1,2) was employed for a detailed study of their fragmentation, clarifying some controversial aspects of previous investigations on these compounds. Losses of neutral fatty acids from the acyl side chains (i.e. [M−H−RxCOOH]−, x =1,2) were found to prevail over ketene losses or generation of long-chain fatty acid (FA) anions [RxCOO]−, x =1,2). The chain length, degree of unsaturation and positional distribution of the FAs attached to the primary (sn1) and secondary (sn2) hydroxyl groups of the glycerol moiety were established for all SQDG species identified in a sample extract of spinach leaves. The systematically observed preferential loss of FAs from the sn1 position of the glycerol backbone was exploited for the regiochemical assignment of the investigated species (3). The prevailing presence of a 16:0 (i.e., palmitic) acyl chain on the glycerol sn2 position of SQDGs suggests a prokaryotic path as the main route for their biosynthesis in spinach leaves (4). We envision that the versatility of this CID MS/MS approach, with ability to establish the regiochemistry of the acyl chains of SQDGs, will enable the systematic investigation of photosynthetic plants, algae, cyanobacteria, purple sulfur and non-sulfur bacteria with broad implications within and beyond the realm of sulfolipids and their involvement in membrane structures and cell communication.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
