Extradiol dioxygenases are known to oxidatively cleave aromatic pollutants, such as catechol. DfdB is an extradiol dioxygenase whose activity on substituted catechols has not been studied. Catechols and other aromatic hydrocarbons are a by-product of coal conversion, coal tar chemical production and other coal industries and are found in the air and wastewater surrounding these facilities. As catechol substrates are possible human carcinogens, their potential breakdown by DfdB is a significant area of interest. Ultimately, this research aims to define the conditions under which DfdB breaks down catechol substrates most efficiently and characterize the products of this bioremediation pathway. To accomplish this goal, the enzyme kinetics of DfdB were measured with varying concentrations of catechol substrates using Ultraviolet-Visible (UV-vis) Spectroscopy, and initial rates of reaction were calculated. Upon analysis, the data suggests that DfdB experiences concentration-dependent substrate inhibition, which has been noted for other extradiol dioxygenases. By measuring kinetic profiles for a variety of substituted catechols, we have better defined the characteristics of DfdB as a potential bioremediation catalyst. This information will be leveraged to improve the utility of this catalyst broadly for synthesis and bioremediation.
