Haloalkane dehalogenases: Biotechnological applications

Haloalkane dehalogenases (EC 3.8.1.5) are alfa/beta-hydrolases cleaving a carbon-halogen bond in more than hundred halogenated aliphatic and cyclic compounds. Due to interesting chemistry, broad substrate specificity and high robustness, the members of this enzyme family have been employed in several practical applications: (i) biocatalytic preparation of optically pure building-blocks for organic synthesis, (ii) recycling of by-products from chemical processes, (iii) bioremediation of toxic environmental pollutants, (iv) decontamination of warfare agents, (v) biosensing of environmental pollutants, and (vi) protein tagging for cell imaging and protein analysis. The review discusses these applications in the context of biochemical properties of individual enzymes, when nine out of seventeen characterized enzymes possess properties suitable for practical applications. Further exploration of haloalkane dehalogenases in biotechnologies will require additional research to solve the limiting factors, such as low expression, product inhibition, insufficient enzyme selectivity, low affinity and catalytic efficiency towards selected substrates, or instability in the presence of organic co-solvents. These limitations will be overcomed by the methods of protein engineering, while the new enzymes will be continuously isolated from organisms colonizing diverse environments.