Table 1.
Characterization of novel PG-based ARs and BPGs with representative fragmentation patterns observed (for abbreviations see text). Sequential losses of alkyl chains are shown together with fragmentation of the headgroup when remaining attached to the glycerol backbone containing a C20:0 chain. Values in brackets indicate loss from the most direct precursor, not from the parent ion; (*) denotes presence of unsaturation or OH-group in isoprenoidal chains, which were not exactly determined by MS2 spectra; **loss of OH-phytanyl chain and hexose from the headgroup; (***) loss of serine plus water from the headgroup with two chains still attached (see Figure 2). Fragments due to losses of alkyl chains are coded: underscored (fragment resulting from loss of an unsaturated chain), bold (fragment resulting from loss of C25 chain) and italics (fragment resulting from loss of a hydroxylated phytanyl chain). Additional losses of H2O occur in hydroxylated alkyl moieties, but are not specified here. All parent ions identified show Δm < 3 ppm; all fragments identified have Δm < 5 ppm. Δm = (m/z measured − m/z calculated)/m/z calculated.
| m/z | Chain characterization | Fragmentation due to losses of chains (loss of) | Headgroup attached to glycerol containing a C20:0 chain (loss of) | GPG fragment | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1st chain | 2nd chain | 3rd chain | 4th chain | C3H8O3 | PO2 | C3H8O3 | PO2 | |||||||
| PGPG-AR | 961.687 | C20:0 | C20:0 | — | — | 681.374 (280.3) | 589.326 (92.0) | |||||||
|
| ||||||||||||||
| PGPG-OH-AR | 977.682 | OH–C20:0 | C20:0 | — | — | 681.374 (296.3) | 589.326 (92.0) | 527.370 (62.0) | 435.324 (92.0) | 355.357 (62.0) | ||||
|
| ||||||||||||||
| OH BPG-1 | 1538.308 | OH–C20:0 | C20:0 | C20:0 | C20:0 | |||||||||
| 1526.214 | C20:3 | C20:3 | OH–C20:0 | C20:0 |
1251.948
(274.3) |
977.682
(274.3) |
||||||||
|
| ||||||||||||||
| diOH BPG-1 | 1554.303 | OH–C20:0 | OH–C20:0 | C20:0 | C20:0 | 1257.995 (296.3) | 961.687 (296.3) | |||||||
| 1544.224 | *OH–C20:0 | *OH–C20:0 | *C20:3 | *C20:2 | ||||||||||
|
| ||||||||||||||
| BPG-2 | 1581.199 (NH4 +) | *C25:5 | *C20:3 | *C20:3 | *C20:3 |
401.061
(1180.1) |
||||||||
|
| ||||||||||||||
| OH BPG-2 | 1598.308 | C25:5 | OH–C20:0 | C20:0 | C20:0 |
1257.995
(340.3) |
961.687 (296.3) | |||||||
| 1594.277 | C25:5 | C20:2 | OH–C20:0 | C20:0 |
1253.963
(340.3) |
977.682
(276.3) |
||||||||
| 1592.261 | C25:5 | C20:3 | OH–C20:0 | C20:0 |
1251.948
(340.3) |
977.682
(274.3) |
681.374 (296.3) | |||||||
| 1582.183 | C25:5 | C20:4 | C20:4 | OH–C20:0 |
697.369
(884.8) |
401.061 (296.3) | ||||||||
|
| ||||||||||||||
| diOH BPG-2 | 1624.381 | OH–C20:0 | OH–C20:0 | C25:0 | C20:0 | 1328.073 (296.3) | 1031.765 (296.3) | |||||||
| 1614.303 | C25:5 | OH–C20:0 | OH–C20:0 | C20:0 |
1273.990
(340.3) |
977.682 (296.3) | 681.374 (296.3) | 401.061 (280.3) | 589.326 (92.0) | 527.370 (62.0) | 435.324 (92.0) | 247.058 | ||
| 1608.256 | C25:5 | OH–C20:3 | OH–C20:0 | C20:0 |
1267.947
(340.3) |
977.682
(290.3) |
681.374 (296.3) | 589.326 (92.0) | 527.370 (62.0) | 435.324 (92.0) | 247.058 | |||
|
| ||||||||||||||
| OH BPG-3 | 1668.39 | *C25:5 | *C25:5 | *OH–C20:0 | *C20:0 | |||||||||
| OH BPG-3 | 1652.261 | C25:5 | C25:5 | C20:3 | OH–C20:0 |
1311.948
(340.3) |
1037.682
(274.3) |
697.369
(340.3) |
401.061 (296.3) | |||||
|
| ||||||||||||||
| diOH BPG-3 | 1684.381 | C25:5 | OH–C20:0 | OH–C20:0 | C25:0 |
1344.068
(340.3) |
1047.760 (296.3) | 751.452 (296.3) | ||||||
| 1676.318 | C25:5 | C25:4 | OH–C20:0 | OH–C20:0 |
1336.005
(340.3) |
933.677
(340.3) |
697.369 (296.3) | 401.061 (296.3) | ||||||
| 1674.303 | C25:5 | C25:5 | OH–C20:0 | OH–C20:0 |
1333.990
(340.3) |
933.677
(340.3) |
697.369 (296.3) | 401.061 (296.3) | ||||||
| 1670.271 | C25:5 | C25:4 | OH–C20:3 | OH–C20:0 |
987.630
(682.6) |
697.369
(290.3) |
401.061 (296.3) | |||||||
|
| ||||||||||||||
| Gly-BPG | 1776.355 | C25:5 | OH–C20:0 | OH–C20:0 | C20:0 |
1436.042
(340.3) |
1139.734 (296.3) | 681.373** (296.3 + 162.1) | ||||||
|
| ||||||||||||||
| Ser-BPG | 1701.335 | C25:5 | OH–C20:0 | OH–C20:0 | C20:0 |
1361.022
(340.3) |
1064.714 (296.3) | 959.671 (105.0)*** | ||||||