Cold-Adapted Bacterium Haloalkane Dehalogenase from a Biochemical Characterization of a Novel

aloalkane dehalogenases (HLDs) (EC 3.8.1.5) are enzymes thatcatalyzethehydrolysisofacarbon-halogenbondinhalogenatedaliphatic hydrocarbons, releasing a corresponding alcohol, a halideion,andaprotonasthereactionproducts(17).HLDscatalyzereac-tionsofgreatenvironmentalandbiotechnologicalsignificance.Theyhavepotentialapplicationsinbioremediation(33),biosensing(4,6),decontamination of warfare agents (30), synthesis of optically purecompounds(29, 35),cellularimaging,andproteinanalysis(25,27).The effective use of biocatalysts in these applications requires avail-ability of enzymes with specific properties under process conditions(5).Isolationofnovelenzymesfromextremophilicmicroorganismsrepresents an effective approach for obtaining biocatalysts with de-sired properties (34). The requirement of low temperature for se-lected practical applications of HLDs prompted us to explore thedomainofpsychrophilicproteins(7).ToidentifyHLDswithpotentiallypsychrophilicproperties,we performed sequence database searches. We used six HLDfamily members—LinB (26), DhaA (23), DhlA (21), DmbB(19), DrbA (20), and DmbC (20)—as queries for the PSI-BLAST (1) search against the nr database of NCBI (February2009version)(32).PSI-BLASTwasconductedwiththe