halidohydrolases

Halidohydrolases are a class of enzymes that catalyze the hydrolysis of bonds in halogenated organic or inorganic compounds. The term derives from the Greek root *halide*, meaning salt, and *hydrolase*, a hydrolase that acts on halide-containing substrates. These enzymes play a key role in the degradation of halogenated pollutants, such as chlorinated solvents, brominated flame retardants, and organophosphate pesticides. By cleaving carbon–halogen or carbon–oxygen bonds, halidohydrolases transform toxic molecules into less harmful or more easily metabolizable forms, thereby contributing to bioremediation efforts in contaminated environments.

Biochemically, halidohydrolases belong to several enzyme families, including haloalkane dehalogenases, haloacetate dehalogenases, and haloperoxidases. They typically function as hydrolases, oxidoreductases, or lyases, depending on the specific reaction. Their active sites often contain metal ions such as iron, manganese, or zinc that facilitate the stabilization of reaction intermediates. Many halidohydrolases exhibit broad substrate specificity, allowing them to act on a range of halogenated structures. However, some enzymes have evolved remarkable selectivity, targeting specific halopropyl groups or chlorinated hydrocarbons.

The distribution of halidohydrolases is widespread across bacteria, fungi, and some archaea. In soil and sediment microbial communities, these enzymes are frequently upregulated in response to halogenated compounds, reflecting adaptive mechanisms to xenobiotic stress. Genetic studies indicate that the genes encoding halidohydrolases are often organized in operons with regulatory elements, transporters, and cofactor biosynthesis pathways. Horizontal gene transfer has been implicated in the spread of halidohydrolase genes among bacterial species.

In applied settings, engineered halidohydrolases are employed in wastewater treatment, underground plume cleanup, and industrial processes that require the dehalogenation of synthetic intermediates. Advances in protein engineering and directed evolution have improved the thermal stability, catalytic efficiency, and substrate range of these enzymes, making them attractive tools for environmental biotechnology.