Table 1. Separation of lipids into groups based on their headgroup type or tail saturation.
The lipids are grouped into subtypes, depending on their headgroup type and tail saturation. Lipids are considered to be fully saturated, if they contain no double bonds in any of the tails. Lipids are considered to be monounsaturated, if they contain exactly one double bond in one or both of the tails. Lipids are considered to be polyunsaturated, if they contain at least two double bonds in one or both of the tails*.
| Group name | Abbrev. | Martini lipids |
|---|---|---|
| Phosphatidylcholines | PC | DAPC, DOPC, DPPC, OIPC, OUPC, PAPC, PEPC, PFPC, PIPC, POPC, PUPC |
| Phosphatidylethanolamines | PE | DAPE, DOPE, DUPE, OAPE, OIPE, OUPE, PAPE, PIPE, POPE, PQPE, PUPE |
| Sphingomyelins | SM | BNSM, DBSM, DPSM, DXSM, PBSM, PGSM, PNSM, POSM, XNSM |
| Gangliosides | GM | DBG1, DPG1, DXG1, PNG1, POG1, XNG1, DBG3, DPG3, DXG3, PNG3, POG3, XNG3, DBGS, DPGS, PNGS, POGS |
| Ceramides | CE | DBCE, DPCE, DXCE, PNCE, POCE, XNCE |
| Lysolipids | LPC | APC, IPC, OPC, PPC, UPC, IPE, PPE |
| Diglycerides | DAG | PODG, PIDG, PADG, PUDG |
| Phosphatidylserines | PS | DAPS, DOPS, DPPS, DUPS, OUPS, PAPS, PIPS, POPS, PQPS, PUPS |
| Phosphatidylinositols | PI | POPI, PIPI, PAPI, PUPI |
| Phosphatic acids | PA | POPA, PIPA, PAPA, PUPA |
| Phosphatidylinositol phosphates | PIP | PAP1, PAP2, PAP3, POP1, POP2, POP3 |
| Cholesterol | CHOL | CHOL |
| Fully saturated tails | FS | DPPC, DBSM, DPSM, DXSM, PBSM, DPPS, DBCE, DPCE, DXCE, PPC, PPE, DBG1, DPG1, DXG1, DBG3, DPG3, DXG3, DBGS, DPGS |
| Monounsaturated tails | MU | DOPC, POPC, DOPE, POPE, BNSM, PGSM, PNSM, POSM, XNSM, DOPS, POPS, POPI, POP1, POP2, POP3, POPA, PODG, PNCE, POCE, XNCE, OPC, PNG1, POG1, XNG1, PNG3, POG3, XNG3, PNGS, POGS |
| Polyunsaturated tails | PU | OIPC, OUPC, PAPC, PEPC, PFPC, PIPC, PUPC, OAPE, OIPE, OUPE, PAPE, PIPE, PQPE, PUPE, OUPS, PAPS, PIPS, PQPS, PUPS, PAPI, PIPI, PUPI, PAP1, PAP2, PAP3, PAPA, PIPA, PUPA, PADG, PIDG, PUDG, APC, IPC, UPC, IPE, DAPC, DUPE, DAPE, DAPS, DUPS |
The way in which lipids are grouped by tail saturation is different than in Ingólfsson et al., 2017, where the grouping is based on the total number of double bonds in both lipid tails. Here, the grouping is motivated by the role of lipid oxidation in electroporation, whereby lipid tails containing two or more double bonds are considerably more prone to oxidative damage than tails containing a single double bond. This is because bis-allylic hydrogens are much more easily abstracted by free radicals compared to allylic hydrogens (Reis and Spickett, 2012). Furthermore, membranes made of polyunsaturated lipids (by our definition) were found to be considerably more prone to poration/rupture by mechanical stretching compared to membranes made of lipids containing a single bond in one or both lipid tails (Olbrich et al., 2000). Thus, we consider that a lipid is polyunsaturated only if it contains at least one polyunsaturated tail.