Amphipatic molecules affect the kinetic profile of Pseudomonas putida chlorocatechol 1,2-dioxygenase

Dioxygenases are nonheme iron enzymes that biodegrade recalcitrant compounds, such as catechol and derivatives, released into the environment by modern industry. Intradiol dioxygenases have attracted much attention due to the interest in their use for bioremediation, which has demanded efforts towards understanding their action mechanism and also how to control it. The role of unexpected amphipatic molecules, observed in crystal structures of intradiol dioxygenases, during catalysis has been poorly explored. We report results obtained with the intradiol enzyme chlorocatechol 1,2-dioxygenase (1,2-CCD) from Pseudomonas putida subjected to delipidation. The delipidated enzyme is more stable and shows more cooperative thermal denaturation. The kinetics changes from Michaelis-Menten to a cooperative scheme, indicating that conformational changes propagate between monomers in the absence of amphipatic molecules. Furthermore, these molecules inhibit catalysis, yielding lower v(max) values. To the best of our knowledge, this is the first report concerning the effects of amphipatic molecules on 1,2-CCD function.