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Abstract Il -DyP4, a dye - decolorizing peroxidase （DyP） from Irpex lacteus F17, has a strong ability to oxidise harmful aromatic compounds, implying application potential in the field of environmental protection. However, the low H2O2 stability of Il -DyP4 hinders its practical application. To improve the H2O2 stability of Il -DyP4, oxidation-sensitive amino acids including three Met, one Cys and ten Tyr residues were mutated to less easily oxidizable residues such as Leu, Val and Phe by site-specific mutagenesis. Mutation of the M207 site, located on the surface of the enzyme and far away from the haem group, improved H2O2 stability by 5.3-fold or more. In addition, Y234, also on the enzyme surface, was replaced with Phe and the Y234F mutant displayed 7.3-fold increased H2O2 stability. Furthermore, mutants M207V and Y234F were selected for the decolorization of various types of synthetic dyes, revealing high decolorization activities, especially for M207V with enhanced catalytic activity. The stable DyP mutant M207V has the potential for decolorization of industrial dye wastewater.
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