<p>Microorganisms that can utilise halogenated compounds as growth substrates produce enzymes that cleave carbon-halogen bonds and are commonly called dehalogenases. The hydrolytic dehalogenases catalyse a nucleophilic displacement reaction, with water as the sole co-substrate [<cite idref="PUB00000125"/>]. They are divided into haloalkane dehalogenases and haloacid dehalogenases (HAD). HADs belong to a large superfamily of hydrolases with diverse substrate specificity, which also includes epoxide hydrolases, phosphoglycolate phosphatases, histidinol phosphate phosphatases, nitrophenyl phosphatases and numerous other proteins [<cite idref="PUB00003337"/>]. </p>The mammalian soluble EHs may contain two evolutionarily distinct domains [<cite idref="PUB00001119"/>]. The N-terminal domain is similar to bacterial HADs; the C-terminal domain is similar to soluble plant EH, microsomal EH, and bacterial haloalkane dehalogenase.