Martini lipids details

Martini lipids follow the general Martini philosophy. Each coarse-grained (CG) bead represents ~4 heavy atoms and based on its underlying atoms and associated overall polarity, hydrophobicity, and charge it is assigned to one of Martini’s predefined bead types (e.g. P1, P2, C1, C2, Qa, Qd, ..). The bead type determines the non-bonded levels of interactions, while bonded interactions (bonds, angles, dihedrals) between beads in the same molecule are normally tuned based on reference atomistic simulations. For more information on Martini philosophy and parameterization see:

This general building block strategy aims to increase flexibility and transferability of the force field but not to exactly match the atomistic behavior of a given molecule/lipid. This means that each CG lipid can represent a range of atomistic lipids. For Martini lipids mapping and naming schema, see Table 1.

Table 1 | Lipid fatty acid nomenclature.

One letter names Bead assignment Corresponding to atomistic tails Examples of corresponding fatty acid names
C C C04:0-C06:0 C04:0 butyryl - C06:0 hexanoyl
T CC C08:0-C10:0 C08:0 octanoyl - C10:0 decanoyl
L CCC C12:0-C14:0 C12:0 lauric acid - C14:0 myristoyl
P CCCC C16:0-C18:0 C16:0 palmitic acid - C18:0 stearoyl
B CCCCC C20:0-C22:0 C20:0 arachidoyl - C22:0 behenoyl
X CCCCCC C24:0-C26:0 C24:0 lignoceroyl - C26:0 hexacosanoyl
Y CDC C12:1-C14:1(9c) C14:1(9c) myristoleoyl
O CDCC C16:1-C18:1(9c) C16:1(9c) palmitoleic acid, C18:1(9c) oleic acid
V CCDC C16:1-C18:1(11c) C16:1(11c), C18:1(11c) cis-vaccenic acid, C18:1(12c)
G CCDCC C20:1-C22:1(11c) C20:1(11c) gondoic acid, C22:1(11c), C22:1(13c) erucoyl
N CCCDCC C24:1-C26:1(9c) C24:1(9c) nervonic acid, C26:1(9c)
I CDDC C16:2-C18:2(9-12c) C18:2(9c,12c) linoleic acid
F CDDD C16:3-C18:3(9-15c) C18:3(9c,12c,15c) octadecatrienoyl
E CCDDC C20:2-C22:2(11-16c) C20:2(11c,14c) eicosadienoic acid, C22:2(13c,16c) docosadienoic acid
Q CDDDC C20:3-C22:3(5-14c) C20:3(5c,8c,11c) mead acid, C20:3(8c,11c,14c) dihomo-gamma-linolenic acid
A DDDDC C20:4-C22:5(4-16c) C20:4(5c,8c,11c,14c) arachidonic acid, C22:5(4c,7c,10c,13c,16c) docosapentaenoic acid
U DDDDD C20:5-C22:6(4-19c) C22:6(4c,7c,10c,13c,16c,19c) docosahexaenoic acid
R DDDDDD C24:6-C26:6(6-21c) C24:6(6c,9c,12c,15c,18c,21c) nisinic acid
J TCCC C16:1-C18:1(3t) C16:1(3t) trans-3-hexadecanoic acid
Pa TCC C(d16:1)-C(d18:1) Sphingosine C16 palmitic acid - C18 stearoyl with a trans double bond
Ba TCCC C(d20:1)-C(d22:1) Sphingosine C20 arachidoyl - C22 behenoyl with a trans double bond
Xa TCCCC C(d24:1)-C(d26:1) Sphingosine C24 lignoceroyl - C26 hexacosanoyl with a trans double bond

Each CG bead represents ~4 carbon atoms, therefore, the underlying atomistic mapping is not unique ranges and a few examples are given for each case. The C beads represent a saturated carbon chain, the D beads have 1-2 cis double bounds, and the T beads have a trans double bound. D stands for Di and is used for lipids tails with two of the same fatty acids, e.g. DPPC has two P tails and DOPC has two O tails. aThese tails are for sphingosine lipids and have one C bead less as a few of the first fatty acid carbons are part of the AM1 linker bead.


A large number of lipids have been parameterized for Martini and their description and examples of use can be found in their respective publication, such as:

Additionally, for each lipid a description, a short parameterization section, and relevant references are provided on each lipid’s webpage and in their topology file. For most of the available Martini lipid topologies an initial coordinate file is provided as well as an image for quick reference; these images try to follow the color schema shown in Figure 1.


 

Martini-lipid

Figure 1 | Martini lipid layout and figure colors.