ENZYMATIC DESULFURIZATION OF DIBENZOTHIOPHENE BY A CELL-FREE SYSTEM OF RHODOCOCCUS-ERYTHROPOLIS D-1

The enzymatic desulfurization of dibenzothiophene (DBT) to 2-hydroxybi phenyl (2-HBP) was detected in extracts of Rhodococcus erythropolis D- 1 grown on DBT as a sole source of sulfur. In the dialyzed cell-free e xtracts, NADH was absolutely required for the activity. DBT desulfuriz ation proceeded linearly with the reaction time, and stoichiometric am ounts of 2-HBP were finally formed. The activity was stimulated by inc reasing the protein and NADH concentrations up to 5 mg ml(-1) and 5 mM , respectively, when 0.1 mM DBT was present in the reaction mixture.