Abstract
Here, incorporation of secondary amine by genetic code expansion was used to expand the potential protein templates for artificial enzyme design. Pyrrolysine analogue containing a D-proline could be stably incorporated into proteins, including the multidrug-binding LmrR and nucleotide-binding dihydrofolate reductase (DHFR). Both modified scaffolds were catalytically active, mediating transfer hydrogenation with a relaxed substrate scope. The protein templates played a distinctive role in that, while the LmrR variants were confined to the biomimetic BNAH as the hydride source, the optimal DHFR variant favorably used the pro-R hydride from NADPH for reactions. Due to the cofactor compatibility, the DHFR secondary amine catalysis could also be coupled to an enzymatic recycling scheme. This work has illustrated the unique advantages of using proteins as hosts, and thus the presented concept is expected to find uses in enabling tailored secondary amine catalysis.
Transferability of N-terminal mutations of pyrrolysyl-tRNA synthetase in one species to that in another species on unnatural amino acid incorporation efficiency
