Abstract

Protein cavities can offer highly versatile and engineerable environments for hosting new catalytic sites. However, only a narrow range of functional elements are available to enzyme designers when building new active sites, meaning that many important modes of reactivity are not accessible. Here I will discuss our efforts to overcome these limitations, by encoding new catalytic elements into proteins as non-canonical amino acid side chains. This approach has allowed us to build enzymes with new functions and reactivity modes that were previously inaccessible with protein catalysts. Significantly as our catalyst are genetically encoded, their activities and selectivities can be optimized using directed evolution workflows adapted to an expanded amino acid alphabet. We are optimistic that this integration of enzyme design, genetic code expansion and laboratory evolution can provide a versatile strategy for creating enzymes with catalytic functions not accessible to nature.