Improving monooxygenase for aromatics systhesis

US-based researchers used gene shuffling and saturation mutagenesis to improve the toluene-o-xylene monooxyg enase (ToMO) enzyme from Pseudomonas stutzeri OX1. Nine new reactions of benzene, toluene, and nitrobenzene catalyzed by the enzyme were identified. The researchers created mutant enzymes that produced industrially important 4-methylresorcinol, methylhydroquinone, and 1,2,4-THB, which are not produced in detectable quantities by the wild type enzymes. The mutant enzymes also produced 2-nitrohydroquinone, 4-nitrocatechol, and 3-nitrocatechol from nitroaromatics at accelerated rates. Production of 4-nitrocatechol from p-nitrophenol increased by 4.5-20 times than that of the wild type ToMO.