MMG-1 tails display a more upright orientation parallel to the bilayer normal compared to MMG-6 in non-interdigitated systems. Previous MD simulation work with emollients and disaturated phosphatidylcholines (PC) in the gel phase has exemplified the link between molecular geometry and the overall membrane structure and properties such as tail tilt. For the case of emollients and disaturated PCs, the headgroup size or branching of the tails can result in energetically unfavorable distances between the molecules, and increased tail tilt is required to achieve optimal tail packing. Similarly, the larger tail tilt of MMG-6 possibly serves to maintain an optimal tail packing distance, despite the larger tail splay near the glycerol moiety. Interestingly, tilt angles have been suggested to increase only up to a certain threshold until the bilayer interdigitates, at least in the case of alcohol-induced interdigitation of phospholipids; 50 coarse-grained simulations of Kranenburg et al., did not, however, show an increase in the tilt angle, 51 but this is likely to be due to the relatively large degree of coarse-graining. Therefore, it is possible that MMG-6 interdigitates when the tail tilt alone is not sufficient to maximize the van der Waals interactions. However, the enthalpic penalty of changing from a tilted tail configuration to that observed in the interdigitated state (Figure ) may counteract this.