Engineering of Rare Earth Binding Proteins for Greener Extractions

Rare earth elements (REEs) are a group of metals with a vast range of applications including electric motors, lasers, GPS, and batteries. Unfortunately, extraction and separation of REEs has considerable negative environmental impacts due to the use of large amounts of acidic and organic solvents. Separation of REEs is further complicated by the highly similar chemical and physical properties of REEs and their relatively low abundance compared to other metals such as calcium and magnesium. To date, no synthetic molecules have demonstrated selectivity within REEs. Recently, a protein known as LanModulin (LanM) was discovered that has markedly high affinity for REEs, even in the presence of millimolar concentrations of calcium. We hypothesized that LanM and other metal-binding proteins could serve as a starting point to engineer proteins with high selectivity for select REEs. We have begun dissecting the fundamental forces of REE-binding in LanM using computational and experimental efforts. The metal binding affinity of individual domains of LanM has been investigated via UV/Vis spectroscopy. We will leverage our results to design improved variants with high selectivity for specific REEs. These LanM analogues will be deployed to develop greener methods for REE extraction and allow for new sources of REEs (such as electronic waste) to be utilized.