Developing and Testing of Lipid Force Fields with Applications to Modeling Cellular Membranes

The amphipathic nature of the lipid molecule (hydrophilic head and hydrophobic tails) enables it to act as a barrier between fluids with various properties and to sustain an environment where the processes critical to life may proceed. While computer simulations of biomolecules primarily investigate protein conformation and binding to drug-like molecules, these interactions often occur in the context of a lipid membrane. Chemical specificity of lipid models is essential to accurately represent the complex environment of the lipid membrane. This review discusses the development and performance of currently used chemically specific lipid force fields (FF) such as the CHARMM, AMBER, GROMOS, OPLS, and MARTINI families. Considerations in lipid FF development including lipid diversity, temperature dependence, phase behavior, and effects of atomic polarizability are considered, as well as methods and goals of parametrization. Applications of these FFs to complex and diverse models for cellular membranes are summarized. Lastly, areas for future development, such as efficient inclusion of long-range Lennard-Jones interactions (significant in transitions from polar to apolar media), accurate transmembrane dipole potential, and diffusion under periodic boundary conditions are considered.