reported by Tawfik and coworkers using a 5,7-dichloro Kemp substrate, as well as 1.2•10 5 M -1 s -1 obtained by computational design using a minimalist approach using the HG3 eliminase as a starting scaffold while incorporating key mutations from the HG3 evolutionary trajectory towards HG3.17 into the design process towards the new Kemp eliminase, HG4. 100 This is significant because our crystal structures show that, unlike other Kemp eliminases such as HG3 or KE07, in the present case it was possible to obtain significant enhancements in catalytic activity without the need for major structural reorganization of the active site.