Engineering De Novo Proteins for Rare Earth Element Extraction

We have recently identified a de novo protein, called S824, that selectively binds specific rare-earth elements. De novo proteins are not found in nature and drive specific protein folding as well as protein functions. S824 contains two REE binding sites that do not bind naturally occurring metal ions such as copper, zinc, or nickel. Thus, S824 serves as an ideal candidate for separating REEs out of waste streams which commonly contain less valuable metals such as Cu, Zn, and Ca. These separations of REE from effluent mining streams enables for higher recovery that would otherwise go to waste and provides an economic advantage to this type of separation.

This is why we hope to find an alternative solution with our de novo protein, S824. De novo proteins are easily modified without changing protein structure, enabling tunability to various REEs. This protein is being generated via BL21(DE3) component E. Coli cells, enabling scale-up for commercial use. Following protein purification, we measure binding using dialysis to remove excess REE, followed by ICP-MS. We demonstrate the ability of S824 to selectively bind terbium over other REEs, indicating a promising first step to a library of proteins capable of purifying individual REEs. Our hope is to have a reusable, environmentally friendly solution for extracting these rare earth metals without the environmental or monetary downsides.