However the conjugation of a polar group with glucuronic acid can only occur after the glucuronic acid has been activated. II reaction is sulfate conjugation. As with glucuronic acid, the sulfate needs to be activated before the reaction with the substrate can take place. Glutathione conjugation eventually results in the formation of Mercapturic acids. These reactions take place with a wide variety of substances, which often have a reactive group, such as a halogen atom.
Examples are the conjugations of dichloronitrobenzene and bromocyclohexane with glutathione.
These substances eventually form mercapturic acids and are excreted. Epoxides can also be metabolized to mercapturic acids by glutathione conjugation. The mercapturic acid formation proceeds via a number of reactions. Benzene metabolism, with the reactive intermediate benzene epoxide, again serves as a good example. This enzyme is responsible for the detoxification of epoxides by hydration.