Glutathione Conjugation and Contaminant Transformation

Field, Jennifer A.; Thurman, E. Michael

doi:10.1021/es950287d

Cited by 105 publications

(97 citation statements)

References 104 publications

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“…Metolachlor ESA was the dominant metabolite for both the grassed and the control systems. ESA is believed to result from a glutathione conjugation (23). Such a conjugation could The mg/kg of metolachlor equiv based on specific activity ) 0.24 µCi/mg of metolachlor applied and dry wt of soil and wet wt of plant material.…”

Section: Mg/kg; 419 µCi)mentioning

confidence: 99%

Mass Balance of Metolachlor in a Grassed Phytoremediation System

Henderson

Belden

Coats

2007

Environ. Sci. Technol.

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Metolachlor is a point-source pollutant at agrochemical dealerships in the Midwest, as well as a non pointsource contaminant of surface waters caused by runoff. Prairie grasses have been used in filter strips to control runoff and are also useful for phytoremediation; however, little is known about the fate of metolachlor and its metabolites within a grassed system. Effects of uptake by prairie grasses on the formation and fate of degradation products are not known. In this study, [U-ring-14C]metolachlor was added to enclosed systems to determine the fate of the parent compound and its metabolites in soil and plants. Mineralization and volatilization were monitored over the 97 day study and found to be 1.05 and 0.2%, respectively, for vegetated systems. At the end of the study, soil and plant material was evaluated for the presence of parent metolachlor and selected metabolites, as well as bound residues. Metolachlor ethane sulfonic acid was the dominant metabolite in soil and plant tissue. Over 7% of applied radioactivity was taken up by the grasses, and plant uptake/metabolism appeared to be the main mechanism for phytoremediation of metolachlor. Vegetation significantly reduced the amount of metolachlor in soil by 9%, indicating potential success as a remediation tool. Metolachlor is a point-source pollutant at agrochemical dealerships in the Midwest, as well as a non point-source contaminant of surface waters caused by runoff. Prairie grasses have been used in filter strips to control runoff and are also useful for phytoremediation; however, little is known about the fate of metolachlor and its metabolites within a grassed system. Effects of uptake by prairie grasses on the formation and fate of degradation products are not known. In this study, [U-ring-14 C]metolachlor was added to enclosed systems to determine the fate of the parent compound and its metabolites in soil and plants. Mineralization and volatilization were monitored over the 97 day study and found to be 1.05 and 0.2%, respectively, for vegetated systems. At the end of the study, soil and plant material was evaluated for the presence of parent metolachlor and selected metabolites, as well as bound residues. Metolachlor ethane sulfonic acid was the dominant metabolite in soil and plant tissue. Over 7% of applied radioactivity was taken up by the grasses, and plant uptake/metabolism appeared to be the main mechanism for phytoremediation of metolachlor. Vegetation significantly reduced the amount of metolachlor in soil by 9%, indicating potential success as a remediation tool. Disciplines Agronomy and Crop Sciences | Entomology Mass Balance of Metolachlor in a Grassed Phytoremediation System

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Section: Mg/kg; 419 µCi)mentioning

confidence: 99%

Mass Balance of Metolachlor in a Grassed Phytoremediation System

Henderson

Belden

Coats

2007

Environ. Sci. Technol.

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“…Many of these compounds are very simple, and, as in the case of the naphthalenesulfonate, representative for a large number of substituted compounds. The azo dyestu¡, tartrazine, represents a widely used class of dyestu¡s.`Alachlorethanesulfonate' represents a class of compounds formed from chloroacetanilide herbicides, alachlor in this case [36]. More information on xenobiotic sulfonates can be found elsewhere (e.g.…”

Section: Hydrolytic Desulfonation Of Aliphatic Compoundsmentioning

confidence: 99%

Microbial desulfonation

Cook

1998

FEMS Microbiology Reviews

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Organosulfonates are widespread compounds, be they natural products of low or high molecular weight, or xenobiotics. Many commonly found compounds are subject to desulfonation, even if it is not certain whether all the corresponding enzymes are widely expressed in nature. Sulfonates require transport systems to cross the cell membrane, but few physiological data and no biochemical data on this topic are available, though the sequences of some of the appropriate genes are known. Desulfonative enzymes in aerobic bacteria are generally regulated by induction, if the sulfonate is serving as a carbon and energy source, or by a global network for sulfur scavenging (sulfate starvation induced (SSI) stimulon) if the sulfonate is serving as a source of sulfur. It is unclear whether an SSI regulation is found in anaerobes. The anaerobic bacteria examined can express the degradative enzymes constitutively, if the sulfonate is being utilized as a carbon source, but enzyme induction has also been observed. At least three general mechanisms of desulfonation are recognisable or postulated in the aerobic catabolism of sulfonates: (1) activate the carbon neighboring the C y Q bond and release of sulfite assisted by a thiamine pyrophosphate cofactor; (2) destabilize the C y Q bond by addition of an oxygen atom to the same carbon, usually directly by oxygenation, and loss of the good leaving group, sulfite; (3) an unidentified, formally reductive reaction. Under SSIS control, different variants of mechanism (2) can be seen. Catabolism of sulfonates by anaerobes was discovered recently, and the degradation of taurine involves mechanism (1). When anaerobes assimilate sulfonate sulfur, there is one common, unknown mechanism to desulfonate the inert aromatic compounds and another to desulfonate inert aliphatic compounds; taurine seems to be desulfonated by mechanism (1).

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“…Glutathione conjugation is the common detoxification method for metolachlor in plants (Cole, 1994;Field and Thurman, 1996) and for its microbial degradation pathway in soil unsaturated zones (Aga and Thurman, 2001;Aga et al, 1996;Aly and Schröder, 2008;Domagalski et al, 2008). In both plant and microbial degradation, glutathione-S-transferase mediates glutathione nucleophilic substitution at the chlorinated carbon of metolachlor.…”

Section: Introductionmentioning

confidence: 99%

“…In both plant and microbial degradation, glutathione-S-transferase mediates glutathione nucleophilic substitution at the chlorinated carbon of metolachlor. Under aerobic conditions and through a variety of enzymatic cleavages, this conjugate gives rise to several compounds, one of which is MESA {2-[2-ethyl-N-(1-methoxypropan-2-yl)-6-methylanilino]-2-oxoethanesulfonic acid} (Al-Khatib et al, 2002;Feng, 1991;Field and Thurman, 1996;Graham et al, 1999).…”

Section: Introductionmentioning

confidence: 99%