A mechanistic perspective on bacterial metabolism of chlorinated methanes |
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| Authors: | Lawrence P. Wackett Michael S. P. Logan Frank A. Blocki Cai Bao-li |
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| Affiliation: | (1) Department of Biochemistry, University of Minnesota, 55108 St. Paul, MN, USA;(2) Institute for Advanced Studies in Biological Process Technology, University of Minnesota, 55108 St. Paul, MN, USA;(3) Institute of Molecular Biology, Nankai University, Tianjin, People's Republic of China |
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| Abstract: | Chlorinated methanes are important environmental pollutants, which can be metabolized by bacteria. The biotransformation of chlorinated methanes by bacteria has been shown to be due either to gratuitous metabolism (cometabolism) or their use as a source of carbon and energy. The reactions which result in carbon-halogen bond cleavage include substitutive, reductive, oxygenative, and gem-elimination mechanisms. Certain methylotrophic bacteria can use dichloromethane as a source of carbon and energy. Dichloromethane dehalogenase catalyzes the first substitutive reaction in this metabolism. The enzyme shows a 1010-fold rate enhancement over the reaction of the bisulfide anion with dichloromethane in water. Pseudomonas putida G786 synthesizes cytochrome P-450CAM which catalyzes the gratuitous reduction of chlorinated methanes. These studies with purified enzymes are beginning to reveal more detailed mechanistic features of bacterial chlorinated methane metabolism.Abbreviations DNA deoxyribonucleic acid - kcat catalytic first order rate constant for an enzyme catalyzed reaction - KM Michaelis constant for an enzyme catalyzed reaction - MNDO modified neglect of diatomic overlap - PIMA pattern induced multialignment - DCMD dichloromethane dehalogenase |
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| Keywords: | chloromethanes chlorofluoromethanes mechanisms bacteria dehalogenation biodegradation |
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