Enzyme thermostability is a property of great importance in the era of designed biocatalysts. While enzymes are capable of catalyzing reactions with exquisite specificity and selectivity, they are often limited by insufficient stability. Improvements in enzyme activity through protein engineering often come at the cost of reduced stability. This is likely a result of both natural drift and a tradeoff that often exists between activity and stability for many single residue substitutions (1 ). However, as exemplified by thermophilic organisms (2 ,3 ) and demonstrated by laboratory evolution (4 –6 ), it is often possible to improve enzyme stability without sacrificing activity. Thus, enzyme thermostability is an attractive optimization target in bioengineering.
