Microbial hydrolytic haloalkane dehalogenases catalyze the cleavage of halogen-carbon bonds of a variety of aliphatic halogenated compounds, including a broad range of chlorinated (C2 –C6 ) and brominated (C2 –C8 ) alkanes, with water as the sole co-substrate, resulting in the production of halide ions, protons, and alcohols (1 ,2 ). Based primarily on substrate specificity and sequence homology, these enzymes have been classified into two general classes that are represented by the enzymes fromXanthobacter autotrophicusGJ10 andRhodococcus rhodochrous(3 ). The study of these enzymes has been motivated largely by their potential use in waste treatment, bioremediation and industrial biocatalysis (4 ,5 ). A substantial amount of mechanistic and structural information is available for these enzymes (6 –9 ).
