(467f) Understanding Cerium Binding Affinity in Lanmodulin Derived Peptides

The re-processing of industrial waste streams and recovery of rare earth elements (REEs) is desired for a green and circular economy. There is an urgent need to identify efficient separation methods that recycle REEs from the waste streams and provide a steady, domestic source of these elements. Among several approaches that have been proposed, bio-based strategies have been given extensive attention due to several technical and environmental advantages such as high selectivity, high regeneration, fast kinetics, eco-friendly chemicals, and low cost. In the present work, we designed two peptides derived from the EF hand loop I of lanmodulin and assessed their binding affinity for the cerium (III) ion. Both experimental and simulation techniques are used to explore the binding potential of these novel peptides and investigate the underlying molecular mechanisms.

Here, we present the preliminary results from circular dichroism (CD) analysis of two peptide sequences with cerium ions at different molar ratios. The results indicate that there is a change in the conformation of the peptides upon cerium loading and thus, provide an indication for binding. The CD results are fitted to a binding model to estimate the dissociation constant (Kd). Isothermal titration calorimetry (ITC) is utilized to confirm the dissociation constant in solution and obtain thermodynamic understanding. Molecular simulations techniques have become important tools in the interpretation of the experimental results and provide insight at an atomic and molecular scale. Therefore, we used Molecular Dynamics (MD) simulation methods to perform a configurational analysis of the peptide-cerium ion complex in water. Several atomic-scale analyses are performed to corroborate experimental results including radius of gyration, radial distribution functions, water coordination in the binding site, and intermolecular interactions. Finally, the dissociation constant of surface-bound peptides is measured using quartz crystal microbalance with dissipation (QCM-D). Overall, the results from the experiment and simulation confirm that the designed peptides have a strong affinity for cerium ions and have the potential to be used in future separation technologies.