An artificial aldolase has been optimized using an ultrahigh-throughput microfluidic screening assay. The evolved enzyme exhibits excellent stereoselectivity and broad substrate scope. Structural studies suggest that a Lys-Tyr-Asn-Tyr catalytic tetrad, which emerged during directed evolution, is responsible for the >109 rate enhancement achieved by this catalyst.
Emergence of a catalytic tetrad during evolution of a highly active artificial aldolase