Partial purification, stereospecificity and stoichiometry of three dehalogenases from aRhizobiumspecies

A fast-growing species of Rhizobium that utilized 2,2-dichloropropionate (2,2DCP) and d,l-2-chloropropionate (dl-2CP) as sole sources of carbon and energy was shown to contain three inducible dehalogenases. These enzymes differed in their substrate specificities: dehalogenase II degraded 2,2DCP, d- and l-2CP, monochloroacetate (MCA) and dichloroacetate (DCA) whilst dehalogenase I showed activity only towards l-2CP and DCA. Dehalogenase III liberated halide from d-2CP and MCA. This is the first report of a dehalogenase acting solely on the d-isomer of a haloalkanoate. All three dehalogenases inverted the isomeric configuration during dehalogenation, forming d(−) and l(+) lactate from l- and d-2CP, respectively.