Sought after for their paramagnetic qualities, rare earth elements are used in a multitude of modern technology particularly as batteries and magnets. These elements which consist of the lanthanide series in addition to yttrium and scandium are challenging to recover from mines and difficult to recycle, but because of their use in green energy technology, there are growing efforts to use bio-inspired separation methods to recover these critical materials. Experimental researchers have identified some protein and peptide sequences with promising initial results, but there has been limited exploration of this space via physics based molecular modeling techniques. Techniques like molecular dynamics (MD) simulations can provide a wealth of knowledge that can be uncovered by analyzing structure, dynamics, and energetics of key events like ion binding. This presentation is a computational investigation of the lanthanide binding protein Lanmodulin. We determine the equilibrium structure and dynamics of Lanmodulin as a function of ion binding and use enhanced sampling methods such as metadynamics to determine ion binding free-energies and related quantities. By comparing to previously measured Kd values, we also assess the feasibility of modeling the lanthanide oxidation state in water as it interacts with protein binders.
