Enzymatic Reduction of 2,4,6-Trinitrotoluene and Related Nitroarenes: Kinetics Linked to One-Electron Redox Potentials

Riefler, R. Guy; Smets, Barth F.

doi:10.1021/es991422f

Cited by 55 publications

(35 citation statements)

References 36 publications

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“…Similar values were obtained by a pulse radiolysis study (-0.397 V) (Riefler and Smets 2000) and LFER employing H 2 S as the reductant (-0.360 V) (Dunnivant and Schwarzenbach 1992), affording average of -0.38 ± 0.02 V for four independent approaches.…”

Section: One-electron Reduction Potential Of 24-dntsupporting

confidence: 80%

Reductive Transformation of 2,4-Dinitrotoluene: Roles of Iron and Natural Organic Matter

Uchimiya

2009

Aquat Geochem

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This study investigated the effects of redox-active and iron-coordinating functional groups within natural organic matter (NOM) on the electron transfer interactions between Fe(II) and 2,4-dinitrotoluene (2,4-DNT), an energetic residue often encountered in aqueous environments as a propellant component and impurities in 2,4,6-trinitrotoluene (TNT). Experiments were first conducted in homogeneous phases as a function of pH in the presence of ligands that (1) complex iron (e.g., citric acid, oxalic acid), (2) complex and reduce iron (e.g., caffeic acid, ascorbic acid), and (3) humic substances with known carboxyl content and electron transfer capacity. Then, effects of these NOM components on Fe(II) reactivity in heterogeneous media were investigated by introducing goethite. Our results indicate complex catalytic and inhibitory effects of NOM components on the reaction between Fe(II) and 2,4-DNT, depending upon the ability of NOM component to (1) reduce dissolved and particulate Fe(III) (e.g., ascorbic acid), (2) form kinetically labile dissolved Fe(II) reductants (e.g., tiron and caffeic acid), and (3) produce surface-associated Fe(II) species that are accessible to 2,4-DNT.

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Section: One-electron Reduction Potential Of 24-dntsupporting

confidence: 80%

Reductive Transformation of 2,4-Dinitrotoluene: Roles of Iron and Natural Organic Matter

Uchimiya

2009

Aquat Geochem

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“…From the change in NADH and nitroarene concentrations, the stoichiometry of reactant consumption was determined while the NADH consumption profile was translated into a nitroarene consumption profile. Details of this method have been reported previously (48). NAD ؉ inhibition.…”

Section: Methodsmentioning

confidence: 99%

“…Numerous studies have reported the accumulation of hydroxylamino compounds (15,33,46,48), and hydroxylamino and nitroso intermediates may abiotically condense to azoxy dimers that persist (24,27,28,40). TNT is also susceptible to aerobic hydrogenation of the aromatic ring.…”

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confidence: 99%

“…Enzymes that reduce nitroarenes have been purified from bacteria and typically are soluble flavoproteins that use NADH or NADPH as electron donors (10). Examples of known nitroreductases include flavomononucleotide reductases (48), hydrogenases, ferredoxin-like proteins (40), pyruvate:ferredoxin oxidoreductases, sulfite reductases, carbon monoxide dehydrogenases (46), nitrite reductases, quinone reductases (8), and xanthine oxidase (41). For these enzymes, TNT is not the physiological substrate and TNT reduction does not appear to benefit the organism.…”

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confidence: 99%

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NAD(P)H:Flavin Mononucleotide Oxidoreductase Inactivation during 2,4,6-Trinitrotoluene Reduction

Riefler

Smets

2002

Appl Environ Microbiol

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Bacteria readily transform 2,4,6-trinitrotoluene (TNT), a contaminant frequently found at military bases and munitions production facilities, by reduction of the nitro group substituents. In this work, the kinetics of nitroreduction were investigated by using a model nitroreductase, NAD(P)H:flavin mononucleotide (FMN) oxidoreductase. Under mediation by NAD(P)H:FMN oxidoreductase, TNT rapidly reacted with NADH to form 2-hydroxylamino-4,6-dinitrotoluene and 4-hydroxylamino-2,6-dinitrotoluene, whereas 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene were not produced. Progressive loss of activity was observed during TNT reduction, indicating inactivation of the enzyme during transformation. It is likely that a nitrosodinitrotoluene intermediate reacted with the NAD(P)H:FMN oxidoreductase, leading to enzyme inactivation. A half-maximum constant with respect to NADH, K N , of 394 M was measured, indicating possible NADH limitation under typical cellular conditions. A mathematical model that describes the inactivation process and NADH limitation provided a good fit to TNT reduction profiles. This work represents the first step in developing a comprehensive enzyme level understanding of nitroarene biotransformation.2,4,6-Trinitrotoluene (TNT), a widely used explosive, is a contaminant frequently found at military bases and munitions production facilities. In addition to its explosion hazard, TNT is a suspected mutagen (56). Extensive research is under way to determine methods for remediation of soil and groundwater contaminated with this pollutant. Bacteria under both aerobic and anaerobic conditions commonly reduce TNT. The nitrogen atom in a nitro group retains a net positive charge and consequently is a strong electrophile and susceptible to reduction. Nitro groups are typically reduced by the sequential addition of three electron pairs, producing a nitroso group, a hydroxylamino group, and finally an amino group (40, 55). Nitroso intermediates are extremely reactive and account for much of the toxicity associated with nitroarenes (56). Through successive reductions of the nitro groups, microorganisms sequentially transform TNT to aminodinitrotoluenes (ADNTs), diaminonitrotoluenes, and triaminotoluene (13,24,46,49,55). As electron-deficient nitrogen atoms are reduced, the molecule becomes less susceptible to reduction and reaction rates decrease, i.e., TNT is reduced faster than ADNTs and ADNTs are reduced faster than diaminonitrotoluenes (13,33,40,42,46). To date, there is no conclusive evidence that mineralization of TNT via a triaminotoluene pathway occurs.Products other than amino compounds have been identified during bacterial nitroarene reduction. Numerous studies have reported the accumulation of hydroxylamino compounds (15,33,46,48), and hydroxylamino and nitroso intermediates may abiotically condense to azoxy dimers that persist (24,27,28,40). TNT is also susceptible to aerobic hydrogenation of the aromatic ring. Several research groups have reported the formation of a Meisenheimer complex and a di...

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“…Indeed, several prokaryotic FMN-dependent enzymes have received recent attention because they reductively eliminate nitrite from xenobiotic explosive compounds, which can serve as a sole source of nitrogen (Spain, 1995;Binks et al, 1996;Blehert et al, 1997Blehert et al, , 1999French et al, 1998;Nivinskas et al, 2000;Riefler & Smets, 2000;Williams & Bruce, 2000;Barna et al, 2001;Ebert et al, 2001;Meah et al, 2001;Haynes et al, 2002;Johnson et al, 2002;Khan et al, 2002;Koder et al, 2002;Williams & Bruce, 2002;Orville, Manning, Blehert, Studts et al, 2004). Thus, it appears that the reductive enzymes enable some microorganisms to exploit nitrochemicals introduced into the environment by recent human activities.…”

Section: Introductionmentioning

confidence: 99%

Crystallization and preliminary analysis of active nitroalkane oxidase in three crystal forms

Nagpal

Valley

Fitzpatrick

et al. 2004

Acta Crystallogr D Biol Cryst

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Nitroalkane oxidase (NAO), a flavoprotein cloned and purified from Fusarium oxysporum, catalyzes the oxidation of neutral nitroalkanes to the corresponding aldehydes or ketones, with the production of H 2 O 2 and nitrite. In this paper, the crystallization and preliminary X-ray data analysis of three crystal forms of active nitroalkane oxidase are described. The first crystal form belongs to a trigonal space group (either P3 1 21 or P3 2 21, with unit-cell parameters a = b = 103.8, c = 487.0 Å) and diffracts to at least 1.6 Å resolution. Several data sets were collected using 2θ and κ geometry in order to obtain a complete data set to 2.07 Å resolution. Solvent-content and Matthews coefficient analysis suggests that crystal form 1 contains two homotetramers per asymmetric unit. Crystal form 2 (P2 1 2 1 2 1 ; a = 147.3, b = 153.5, c = 169.5 Å) and crystal form 3 (P3 1 or P3 2 ; a = b = 108.9, c = 342.5 Å) are obtained from slightly different conditions and also contain two homotetramers per asymmetric unit, but have different solvent contents. A three-wavelength MAD data set was collected from selenomethionine-enriched NAO (SeMet-NAO) in crystal form 3 and will be used for phasing.

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Enzymatic Reduction of 2,4,6-Trinitrotoluene and Related Nitroarenes: Kinetics Linked to One-Electron Redox Potentials

Cited by 55 publications

References 36 publications

Reductive Transformation of 2,4-Dinitrotoluene: Roles of Iron and Natural Organic Matter

Reductive Transformation of 2,4-Dinitrotoluene: Roles of Iron and Natural Organic Matter

NAD(P)H:Flavin Mononucleotide Oxidoreductase Inactivation during 2,4,6-Trinitrotoluene Reduction

Crystallization and preliminary analysis of active nitroalkane oxidase in three crystal forms

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