Publications

• Dichloromethane dehalogenase with improved catalytic activity isolated from a fast-growing dichloromethane-utilizing bacterium.

  Scholtz R., Wackett L.P., Egli C., Cook A.M., Leisinger T.

  A methylotrophic bacterium, denoted strain DM11, was isolated from groundwater and shown to utilize dichloromethane or dibromomethane as the sole carbon and energy source. The new isolate grew at the high rate of 0.22 h-1 compared with 11 previously characterized dichloromethane-utilizing bacteria ... >> More

  A methylotrophic bacterium, denoted strain DM11, was isolated from groundwater and shown to utilize dichloromethane or dibromomethane as the sole carbon and energy source. The new isolate grew at the high rate of 0.22 h-1 compared with 11 previously characterized dichloromethane-utilizing bacteria (micromax, 0.08 h-1). The dichloromethane dehalogenase from strain DM11 (group B enzyme) was purified by anion-exchange chromatography. It was shown to be substantially different from the set of dichloromethane dehalogenases from the 11 slow-growing strains (group A enzymes) that had previously been demonstrated to be identical. The Vmax for the group B enzyme was 97 mkat/kg of protein, some 5.6-fold higher than that of the group A enzymes. The group A dehalogenases showed hyperbolic saturation with the cosubstrate glutathione, whereas the group B enzyme showed positive cooperativity in glutathione binding. Only 1 of 15 amino acids occupied common positions at the N termini, and amino acid contents were substantially different in group A and group B dehalogenases. Immunological assays demonstrated weak cross-reactivity between the two enzymes. Despite the observed structural and kinetic differences, there is potentially evolutionary relatedness between group A and group B enzymes, as indicated by (i) hybridization of DM11 DNA with a gene probe of the group A enzyme, (ii) a common requirement for glutathione in catalysis, and (iii) similar subunit molecular weights of about 34,000. << Less

  J. Bacteriol. 170:5698-5704(1988) [PubMed] [EuropePMC]

• Dichloromethane dehalogenase of Hyphomicrobium sp. strain DM2.

  Kohler-Staub D., Leisinger T.

  Dichloromethane dehalogenase, a highly inducible glutathione-dependent enzyme catalyzing the conversion of dichloromethane into formaldehyde and inorganic chloride, was purified fivefold with 60% yield from Hyphomicrobium sp. strain DM2. The electrophoretically homogeneous purified enzyme exhibite ... >> More

  Dichloromethane dehalogenase, a highly inducible glutathione-dependent enzyme catalyzing the conversion of dichloromethane into formaldehyde and inorganic chloride, was purified fivefold with 60% yield from Hyphomicrobium sp. strain DM2. The electrophoretically homogeneous purified enzyme exhibited a specific activity of 17.3 mkat/kg of protein. Its pH optimum was 8.5. The enzyme was stable at -20 degrees C for at least 6 months. A subunit molecular weight of 33,000 was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Gel filtration of native dichloromethane dehalogenase yielded a molecular weight of 195,000. Subunit cross-linking with dimethyl suberimidate confirmed the hexameric tertiary structure of the enzyme. Dichloromethane dehalogenase was highly specific for dihalomethanes. Its apparent Km values were 30 microM for CH2Cl2, 15 microM for CH2BrCl, 13 microM for CH2Br2, 5 microM for CH2I2, and 320 microM for glutathione. Several chlorinated aliphatic compounds inhibited the dichloromethane dehalogenase activity of the pure enzyme. The Ki values of the competitive inhibitors 1,2-dichloroethane and 1-chloropropane were 3 and 56 microM, respectively. << Less

  J Bacteriol 162:676-681(1985) [PubMed] [EuropePMC]