Artificial Metalloenzyme Design with Unnatural Amino Acids and Non-Native Cofactors

There are 20 proteinogenic amino acids and a limited number of cofactors naturally available to build enzymes. Genetic codon expansion enables us to incorporate more than 200 unnatural amino acids into proteins using cell translation machinery, greatly expanding structures available to protein chemists. Such tools enable scientists to mimic the active site of an enzyme to tune enzymatic activity, anchor cofactors, and immobilize enzymes on electrode surfaces. Non-native cofactors can be incorporated into the protein through covalent or noncovalent interactions, expanding the reaction scope of existing enzymes. The review discusses strategies to incorporate unnatural amino acids and non-native cofactors and their applications in tuning and expanding enzymatic activities of artificial metalloenzymes.