Individual stages of bacterial dichloromethane degradation mapped by carbon and chlorine stable isotope analysis
| Autor: | M. L. Torgonskaya, Stéphane Vuilleumier, Hans H. Richnow, Steffen Kümmel, Yuri A. Trotsenko, A. M. Zyakun, Kestutis S. Laurinavichius |
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| Rok vydání: | 2017 |
| Předmět: |
Environmental Engineering
chemistry.chemical_element 010501 environmental sciences Photochemistry complex mixtures 01 natural sciences chemistry.chemical_compound Dichloromethane dehalogenase Kinetic isotope effect Chlorine Environmental Chemistry cardiovascular diseases 0105 earth and related environmental sciences General Environmental Science Dichloromethane Dehalogenase Glutathione Transferase Carbon Isotopes Methylene Chloride Bacteria Chemistry Stable isotope ratio 010401 analytical chemistry Isotopes of chlorine General Medicine musculoskeletal system 0104 chemical sciences Biodegradation Environmental cardiovascular system Carbon Water Pollutants Chemical |
| Zdroj: | Journal of environmental sciences (China). 78 |
| ISSN: | 1001-0742 |
| Popis: | The fractionation of carbon and chlorine stable isotopes of dichloromethane (CH2Cl2, DCM) upon dechlorination by cells of the aerobic methylotroph Methylobacterium extorquens DM4 and by purified DCM dehalogenases of the glutathione S-transferase family was analyzed. Isotope effects for individual steps of the multi-stage DCM degradation process, including transfer across the cell wall from the aqueous medium to the cell cytoplasm, dehalogenase binding, and catalytic reaction, were considered. The observed carbon and chlorine isotope fractionation accompanying DCM consumption by cell supensions and enzymes was mainly determined by the breaking of CCl bonds, and not by inflow of DCM into cells. Chlorine isotope effects of DCM dehalogenation were initially masked in high density cultures, presumably due to inverse isotope effects of non-specific DCM oxidation under conditions of oxygen excess. Glutathione cofactor supply remarkably affected the correlation of variations of DCM carbon and chlorine stable isotopes (Δδ13C/Δδ37Cl), increasing corresponding ratio from 7.2-8.6 to 9.6-10.5 under conditions of glutathione deficiency. This suggests that enzymatic reaction of DCM with glutathione thiolate may involve stepwise breaking and making of bonds with the carbon atom of DCM, unlike the uncatalyzed reaction, which is a one-stage process, as shown by quantum-chemical modeling. |
| Databáze: | OpenAIRE |
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