Haloacetate halidohydrolase II specified by a plasmid pUOl was purified from haloacetateassimilating Moraxella sp. B. The purification procedures included protamine treatment, ammoniumsulfate fractionation, and column chromatographies with DEAE-cellulose, hydroxyapatite and Bio-gel P-150, resulting in a 200-fold purification. The purified enzyme was homogeneousby criteria of ultracentrifugation and disc electrophoresis. The molecular weight estimated by Sephadex G-100 gel filtration was 43,000, and it was 26,000 by SDS-polyacrylamide gel electrophoresis.The sedimentation coefficient s% w was 4. 1 S, and the isoelectric point was pH5.2. The amino acid composition was also estimated.The enzyme catalyzed the dehalogenation of monochloro-, monobromo-and monoiodoacetate, but not monofluoroacetate. 2,2-Dichloroacetate and 2-chloropropionate were slightly dehalogenated, but trichloroacetate and 3-chloropropionate were not. The enzymewas very sensitive to inhibition with thiol reagents.

A strain of Moraxella sp. capable of assimilating fluoroacetate (FA) as the sole source of carbon was isolated. It was resistant to mercuric chloride and antibiotics, such as penicillin G and kanamycin. Mercury reductase and haloacetate halidohydrolase were found in the cell-free extract of the organism. Two kinds of halidohydrolase were found on purification by DEAE-cellulose column chromatography; one was active for FA and chloroacetate (CA) (halidohydrolase 1), and the other was active for CAbut not FA (halidohydrolase 2). Twotypes of cured strain were obtained by mitomycin C; type I lost halidohydrolase 2, whereas type II became sensitive to mercuric chloride and lost halidohydrolase 1 and 2. On electrophoresis of plasmid on agarose gel, a plasmid band was observed in a wild strain and a shorter band in type I. However, no band was observed in type II. Transferring of the plasmid by conjugation from a wild cell to a type II cell gave an exconjugant which possessed halidohydrolase 1 and 2 and became resistant to mercury. These results indicate that both halidohydrolase 1 and 2 and also mercury reductase are determined by the plasmid in the organism.

No abstract

Haloacetate halidohydrolase II specified by a plasmid pUOI was purified from haloacetateassimilating Moraxella sp. B. The purification procedures included protamine treatment, ammonium sulfate fractionation, and column chromatographies with DEAE-cellulose, hydroxyapatite and Bio-gel P-150, resulting in a 200-fold purification. The purified enzyme was homogeneous by criteria of ultracentrifugation and disc electrophoresis. The molecular weight estimated by Sephadex G-I00 gel filtration was 43,000, and it was 26,000 by SDS-polyacrylamide gel electrophoresis. The sedimentation coefficient sgo,w was 4.1 S, and the isoelectric point was pH 5.2. The amino acid composition was also estimated. The enzyme catalyzed the dehalogenation of monochloro-, mono bromo-and monoiodoacetate, but not monofiuoroacetate. 2,2-Dichloroacetate and 2-chloropropionate were slightly dehalogenated, but trichloroacetate and 3-chloropropionate were not. The enzyme was very sensitive to inhibition with thiol reagents.