The Third Generation of Artificial Dye-Decolorizing Peroxidase Rationally Designed in Myoglobin

Approaches to degradation of industrial dyes are desirable, of which bioremediation is more favorable. In addition to the use of native enzymes, rational design of artificial enzymes provides an alternative approach. Meanwhile, few designs can achieve a catalytic activity comparable to that of native enzymes. We have previously designed two generations of artificial dye-decolorizing peroxidases (DyPs) in myoglobin (Mb) by introduction of Tyr43 and Trp138 in the heme pocket; however, the activity is moderate. To improve the activity of the artificial DyP, we herein designed a third generation by introduction of an additional Trp (P88W) to the protein surface, named F43Y/F138W/P88W Mb. The third generation of artificial DyP was shown to exhibit a catalytic efficiency exceeding that of various native DyPs and comparable to that of the most efficient native DyPs. Titration of reactive blue 19 (RB19) and molecular docking studies revealed crucial roles of Trp88 in substrate binding and oxidation, which acts as a catalytic site. This study not only provides clues for heme protein design but also suggests that the artificial DyP has potential applications for bioremediation in the future.