Rate of acyl migration in lysophosphatidylcholine (LPC) is dependent upon the nature of the acyl group. Greater stability of sn-2 docosahexaenoyl LPC compared to the more saturated LPC species
Fig 2
Identification of the regioisomers of LPC from the product ion spectra.
The product ion spectra were obtained for the early eluting (peak 1) and late eluting (peak 2) isomers of each LPC as described in Methods. The intensity of the molecular ion as percentage of that of phosphocholine ion (m/z 184) differentiates the two regioisomers, with the sn-1 acyl isomer showing much higher percent of molecular ion [17]. The relative intensities of the molecular ion, expressed as percent of phosphoryl choline ion (m/z 184.1) for the various LPCs are as follows: 16:0 LPC (4.7% for peak 1 and 65.5% for peak 2); 18:1 LPC (3.7% for peak 1 and 44.8% for peak 2); .20:4 LPC (10.2% for peak 1 and 60.5% for peak 2); 22:6 LPC (15.3% for peak 1, and,172% for peak 2). In addition, the choline fragment ion (m/z 104.1) is completely absent from the sn-2 acyl isomers, but was prominently present in all the sn-1 acyl isomers.