Table 1.
Details on peak annotation during MS data analysis
| Assigned deoxySLs | Composition (upon reaction with C175-XX) | m/z | Tolerance ± error |
|---|---|---|---|
| doxCer(16:1)/dox(DH)Cer(16:2) | H76 C42 D4 O2 N5 | 690.6556 | 7 ppm |
| doxCer(16:0)/dox(DH)Cer(16:1) | H78 C42 D4 O2 N5 | 692.6717 | 7 ppm |
| dox(DH)Cer(16:0) | H80 C42 D4 O2 N5 | 694.6866 | 7 ppm |
| doxCer(18:3)/dox(DH)Cer(18:4) | H76 C44 D4 O2 N5 | 714.6542 | 7 ppm |
| doxCer(18:1)/dox(DH)Cer(18:2) | H80 C44 D4 O2 N5 | 718.6853 | 7 ppm |
| doxCer(18:0)/dox(DH)Cer(18:1) | H82 C44 D4 O2 N5 | 720.7031 | 7 ppm |
| dox(DH)Cer(18:0) | H84 C44 D4 O2 N5 | 722.7158 | 7 ppm |
| doxCer(20:0)/dox(DH)Cer(20:1) | H86 C46 D4 O2 N5 | 748.7341 | 7 ppm |
| dox(DH)Cer(20:0) | H88 C46 D4 O2 N5 | 750.7482 | 7 ppm |
| doxCer(22:4)/dox(DH)Cer(22:5) | H82 C48 D4 O2 N5 | 768.7075 | 7 ppm |
| doxCer(22:3)/dox(DH)Cer(22:4) | H84 C48 D4 O2 N5 | 770.7141 | 7 ppm |
| doxCer(22:1)/dox(DH)Cer(22:2) | H88 C48 D4 O2 N5 | 774.7447 | 7 ppm |
| doxCer(22:0)/dox(DH)Cer(22:1) | H90 C48 D4 O2 N5 | 776.7642 | 7 ppm |
| dox(DH)Cer(22:0) | H92 C48 D4 O2 N5 | 778.7804 | 7 ppm |
| doxCer(24:2)/dox(DH)Cer(24:3) | H90 C50 D4 O2 N5 | 800.7664 | 7 ppm |
| doxCer(24:1)/dox(DH)Cer(24:2) | H92 C50 D4 O2 N5 | 802.7819 | 7 ppm |
| doxCer(24:0)/dox(DH)Cer(24:1) | H94 C50 D4 O2 N5 | 804.7975 | 7 ppm |
| dox(DH)Cer(24:0) | H96 C50 D4 O2 N5 | 806.8134 | 7 ppm |
| doxCer(26:1)/dox(DH)Cer(26:2) | H96 C52 D4 O2 N5 | 830.8122 | 7 ppm |
| doxCer(26:0)/dox(DH)Cer(26:1) | H98 C52 D4 O2 N5 | 832.8264 | 7 ppm |
| dox(DH)Cer(26:0) | H100 C52 D4 O2 N5 | 834.8369 | 9 ppm |
| Cer(a18:1) [internal standard] | H80 C44 D4 O3 N5 | 734.6804 | 7 ppm |
Peaks corresponding to the expected masses of alkyne doxCer/dox(DH)cer species after click-reaction with azido-C175-XX compounds were screened for both in MS1 and MS2 scans. A species was positively identified only, if the peak corresponding to the characteristic neutral loss was additionally detected in the MS2 scan. The intensity of the latter peak was used for all subsequent calculations. Ceramide nomenclature: dox denotes a 1-deoxy-17-alkynylsphingoid base backbone. DH indicates the dihydrogenation of the latter, followed by a description of the N-acylated fatty acid in brackets (a indicates the alkynyl moiety at the terminal end, the first digit corresponds to the number of carbon atoms and the second to the number of double bonds, separated by a colon).