The relative conformation simplicity of these chains compared to peptides makes them ideal for testing minima search algorithms and potential function models for biomolecules. The n -alkanes and their derivatives are also predicted to exhibit tertiary structures, as found in proteins. There has been much recent interest in the structure and dynamics of unbranched hydrocarbon chains. Saturated and partially unsaturated hydrocarbon chains, either by themselves or attached to other functional groups such as in a fatty acid, are an important component of various organic polymers, detergents, and self-assembled monolayers. In addition, they make up the hydrophobic ends of phospholipids that form the lipid bilayers of cellular membranes and aid in the anchoring of proteins to these membranes.
Phospholipids containing alkene-like functional groups are also important.
Two examples of these are shown below. The one on the left is phosphatidylcholine containing a cis double bond in one of the fatty acid chains. The ability to determine the number of conformers and their energy and structure is critical to the accurate modeling of systems containing hydrocarbon chains. At present the complete investigation of the conformers of the longer chains is not possible by ab initio electronic structure theory so that molecular modeling must be used with empirical force fields. Complete theoretical enumeration of the conformers for a given size chain is limited by computer speed to the sampling of approximately 15 dihedral angles, i.e., C 17 H 36 for an n -alkane.