Despite the breadth of literature examples available for the application of HHDHs in asymmetric catalysis, these enzymes come with some limitations, which have thus far prevented their wider application in (chemo-)enzymatic synthesis. Chief among these is their relatively specific substrate scope, which typically only includes terminal epoxides. As such, the scarcity of HHDHs for the conversion of sterically demanding internal epoxides limits the chemical space accessible with these enzymes. Since the catalytic promiscuity of HHDHs varies immensely between their different subtypes , the identification of new, catalytically promiscuous HHDHs is of current interest for the development of new asymmetric biocatalytic processes.