Engineering enzymes for oxidizing nitrobenzene

Researchers at the University of Connecticut used DNA shuffling and saturation mutagenesis to generate random mutants as a way to increase the oxidation rate and change the oxidation regiospecificity of nitro aromatics. Improved mutants were successfully produced. One of them produced 4-nitrocatechol 4.5-fold faster and another 20-fold faster than the wild type enzyme. Another mutant changed the regiospecificity of nitrobenzene from 28% of p-nitrophenol to 79%. Manipulation of the enzymes created an enzyme that produces 37% 4-nitrocatechol and 63% nitrohydroquinone from m-nitrophenol, while the original enzyme produced only 4-nitrocatechol. Still another variant formed p-cresol as the major product (93%) from toluene.