Effect of Chirality on the Microbial Degradation and the Environmental Fate of Chiral Pollutants

Kohler, Hans‐Peter E.; Nickel, Kathrin; Zipper, Christian

doi:10.1007/978-1-4615-4187-5_6

Cited by 10 publications

(8 citation statements)

References 83 publications

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“…As other authors have emphasized, it is important to consider both stereochemistry and chirality when studying the effects and degradation potential of chiral compounds (e.g. (Ariëns 1989(Ariëns , 1993Kohler et al 1997Kohler et al , 2000. This is also true when enantiomerically pure compounds are used and therefore only one enantiomer is introduced into the environment.…”

Section: Resultsmentioning

confidence: 99%

“…5, the model postulates that the active enantiomer binds more tightly to the active site of the enzyme because the sequence of the three groups around the asymmetric carbon atom, ABC, forms the triangular face of a tetrahedron that matches the complementary triad on the chiral binding site, A′B′C′, of the active site. The less active enantiomer binds ineffectively, since it has a mirror-image sequence of the three groups, CBA, which leads to a mismatch with the active site (Kohler et al 2000). In some cases, this model needs to be expanded to a so-called four-location model (Mesecar and Koshland Jr. 2000;Fig.…”

Section: Enantioselective Enzymesmentioning

confidence: 99%

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Chirality of pollutants?effects on metabolism and fate

Müller

Köhler

2004

Applied Microbiology and Biotechnology

160

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In most cases, enantiomers of chiral compounds behave differently in biochemical processes. Therefore, the effects and the environmental fate of the enantiomers of chiral pollutants need to be investigated separately. In this review, the different fates of the enantiomers of chiral phenoxyalkanoic acid herbicides, acetamides, organochlorines, and linear alkylbenzenesulfonates are discussed. The focus lies on biological degradation, which may be enantioselective, in contrast to non-biotic conversions. The data show that it is difficult to predict which enantiomer may be enriched and that accumulation of an enantiomer is dependent on the environmental system, the species, and the organ. Racemization and enantiomerization processes occur and make interpretation of the data even more complex. Enantioselective degradation implies that the enzymes involved in the conversion of such compounds are able to differentiate between the enantiomers. "Enzyme pairs" have evolved which exhibit almost identical overall folding. Only subtle differences in their active site determine their enantioselectivities. At the other extreme, there are examples of non-homologous "enzyme pairs" that have developed through convergent evolution to enantioselectively turn over the enantiomers of a chiral compound. For a better understanding of enantioselective reactions, more detailed studies of enzymes involved in enantioselective degradation need to be performed.

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Section: Resultsmentioning

confidence: 99%

Section: Enantioselective Enzymesmentioning

confidence: 99%

Chirality of pollutants?effects on metabolism and fate

Müller

Köhler

2004

Applied Microbiology and Biotechnology

160

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“…Taking into consideration the fact that the toxicity and the effect on biological targets might strongly differ for the enantiomers of a chiral pesticides or drug [16], study of enantioselective metabolism on the molecular level well deserves further emphasis.…”

Section: Discussionmentioning

confidence: 99%

“…Second, strain MH metabolizes the chiral phenoxypropanoic acid herbicides mecoprop and di~hl?r prop in an enantioselective manner. The effect of chirality on the metabolism of chiral pollutants, the importance of treating enantiomers separately, and the necessity of considering stereochemistry when studying degradation and environmental fate of chiral compounds have been emphasized in recent reviews [2,3,14,16]. Strain MH is an ideal system for studying the effect of chirality on the bacterial metabolism of chiral herbicides.…”

Section: Introductionmentioning

confidence: 99%

Sphingomonas herbicidovorans MH: a versatile phenoxyalkanoic acid herbicide degrader

Köhler

1999

Journal of Industrial Microbiology and Biotechnology

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Sphingomonas herbicidovorans MH was isolated from a dichlorprop-degrading soil column. It is able to grow on phenoxyalkanoic acid herbicides, such as mecoprop, dichlorprop, 2,4-D, MCPA, and 2,4-DB. Strain MH utilizes both enantiomers of the chiral herbicides mecoprop and dichlorprop as sole carbon and energy sources. Enantiomer-specific uptake systems are responsible for transporting the acidic substrates across the cell membrane. Catabolism is initiated by two enantiomer-specific alpha-ketoglutarate-dependent dioxygenases that catalyze the cleavage of the ether bond of the respective enantiomer to yield the corresponding phenol and pyruvate. Therefore selective degradation of the enantiomers of mecoprop and dichlorprop by strain MH is not only due to enantioselective catabolism but also to enantioselective transport.

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“…In technical HCH, ␣-HCH is present as a racemic (1:1) mixture of the two enantiomers (1). Enantiomer-specific analyses have revealed various enantiomer compositions of ␣-HCH in environmental and biological samples (5,9,10,16). Molecular details of enantioselectivity are known for a limited selection of chiral pollutants, but not very much is known about the mechanisms of the enantioselective metabolism of ␣-HCH or about the organisms and enzymes involved (17).…”

mentioning

confidence: 99%