Enzymatic dehalogenation of pentachlorophenol by extracts from Arthrobacter sp. strain ATCC 33790.

Arthrobacter sp. strain ATCC 33790 was grown with pentachlorophenol (PCP) as the sole source of carbon and energy. Crude extracts, which were prepared by disruption of the bacteria with a French pressure cell, showed no dehalogenating activity with PCP as the substrate. After sucrose density ultracentrifugation of the crude extract at 145,000 x g, various layers were found in the gradient. One yellow layer showed enzymatic conversion of PCP. One chloride ion was released per molecule of PCP. The product of the enzymatic conversion was tetrachlorohydroquinone. NADPH and oxygen were essential for this reaction. EDTA stimulated the enzymatic activity by 67%. The optimum pH for the enzyme activity was 7.5, and the temperature optimum was 25 degrees C. Enzymatic activity was also detected with 2,4,5-trichlorophenol, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, and 2,3,4,5-tetrachlorophenol as substrates, whereas 3,4,5-trichlorophenol, 2,4-dichlorophenol, 3,4-dichlorophenol, and 4-chlorophenol did not serve as substrates

Purification and characterization of 2-halocarboxylic acid dehalogenase II from Pseudomonas spec. CBS 3.

2-Halocarboxylic acid dehalogenase 2 from Pseudomonas spec. CBS 3 (EC 3.8.1.2), which had been cloned in E. coli Hb 101 was purified to elec- trophoretic homogeneity from crude extracts of E. coli Hb 101 clone 1164. Ammonium sulfate fractionation and three subsequent chromatographic purification steps vielded a pure enzyme in a 230-fold enrichment. The relative molecular masses as determined by gelfiltration on Superose 12 and SDS-polyac-rylamide gel electrophoresis were 64000 Da for the holoenzyme and 29000 Da for the subunit. The isoelectric point, determined by isoelectric focusing, was at pH 6.2. Substrate spezificity towards chlorinated and brominated substrates was limited to short chain monosubstituted 2-halocarboxylic acids. Fluorocompounds were not converted. The reaction proceeded best at a pH above 9.5 and at a reaction temperature of 40-45 Grad C

SIMPLIFIED DETECTION OF BIOLOGICAL HALOGENATION AND DEHALOGENATION WITH A HALIDE SENSOR

Flow injection analysis of halides with a halide selective electrode is a sensitive method to follow changes of halide concentrations which accompany biological halogenation and dehalogenation reactions. Less than 10 picomole chloride or 2 picomole bromide can be detected. At low halide concentrations the halide concentration and the potential change correlate linearily