Shorthand notation for Fatty Acyls (FA)
From LipidomicsWiki
Rules for the annotation
- Shorthand notation: FA number of C-atoms:number of double bonds.
- Functional groups, whose p'ositions in the acyl chain are not known', are shown after the number of double bonds separated by an underscore and followed by the number of groups if more than one.
- Proven positions of functional groups are shown after the number of double bonds (each type of functional group inside a separate pair of parentheses). Positions according to Δ-nomenclature are stated in front of the functional groups that are separated by a comma if more than one.
- Double bond position is indicated by a number according to Δ-nomenclature (geometry unknown), or a number followed by geometry (Z for cis, E for trans).
- Abbreviations for functional groups:
- OH for hydroxyl group.
- O for keto group (it is important to note that “O” before the number of carbons refers to an ether bond)
- Me for methyl branch.
- Order of functional groups: Double bonds - OH - O - Me.
Lipid class abbreviations
- Fatty Acyls - FA
Examples
| Chain type/functional groups | Lipid class level mass$ | Lipid species level§ | Fatty acyl level | LIPID MAPS Fatty acyl structure level |
|---|---|---|---|---|
| Straight-chain | FA (304) | FA 20:4 | FA 20:4 | FA 20:4(4Z,8Z,11Z,4Z) |
| | FA (282) | FA 18:1 | FA 18:1 | FA 18:1(9E) FA 18:1(9) $$ |
| Methyl branched | FA (312) | FA 20:0 | FA 16:0_Me4 | FA 16:0(3Me,7Me,11Me,15Me) |
| Hydroxy | FA (300) | | FA 18:0_OH | FA 18:0(9OH) |
| Keto | FA (200) | FA 12:0 | FA 11:0_O | FA 11:0(3O) |
$ m is the uncharged molecular mass
§ Annotation based on the assumption of a straight-chain fatty acid with no functional groups except double bond(s)
§§ Unknown geometry
