Figure 3.

Structure and physical chemical properties of lipids. Stick diagram of the carbon backbone of lipids with R substituting for the long hydrocarbon portion of fatty acids. Phospholipids found normally in E. coli are in the top row. Foreign lipids that have been introduced into E. coli mutants lacking phosphatidylethanolamine are in the bottom row. The charge nature of the lipid headgroups is noted. Depending on fatty acid composition, solvent, and temperature, those lipids that assume nonbilayer organization in solution are indicated in contrast to those lipids that only form bilayer structures.