Molecular mechanics modeling of the adsorption of methionine on graphite

In this study we were modeling the adsorption of the amino acid methionine on a graphite surface using molecular mechanics calculations. We were employing two different force fields, namely MM+ and AMBER, and considering the molecule in its non-ionic and zwitterionic form. The surface was modeled as a single sheet of graphite. We found that each of the force fields delivers qualitative consistency with experimental results, but the AMBER force field with the parameter set of AMBER3 leads to the best quantitative agreement regarding adsorption energy, bonding energies and distances.