Effect of photosensitizer riboflavin on the fate of 2,4,6-trinitrotoluene in a freshwater environment

Cui, Hua; Hwang, Huey‐Min; Cook, Sean; Zeng, Kui

doi:10.1016/s0045-6535(00)00333-7

Cited by 39 publications

(32 citation statements)

References 8 publications

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“…This is in agreement with a previous report of TNT photolysis in freshwater environment [10]. In that report, two unidentified intermediates were found in the fresh river water sample when riboflavin was present and they disappeared after 60 min.…”

Section: Identification Of Tnt Phototransformation Productssupporting

confidence: 93%

“…Tel. : +1 601 979 2595; fax: +1 601 979 2778. environment and selected TNT phototransformation products were identified [9,10]. Recently, the effect of riboflavin on the phototransformation of benzo[a]pyrene under natural sunlight and UVA irradiation was reported, and the major products in the photolysis of benzo[a]pyrene were identified [11].…”

Section: Introductionmentioning

confidence: 99%

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Phototransformation of 2,4,6-trinitrotoluene: Sensitized by riboflavin under different irradiation spectral range

Yang

Zhao

Hwang

2007

Journal of Hazardous Materials

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Section: Identification Of Tnt Phototransformation Productssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Phototransformation of 2,4,6-trinitrotoluene: Sensitized by riboflavin under different irradiation spectral range

Yang

Zhao

Hwang

2007

Journal of Hazardous Materials

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“…In this study, we found that NbaA is able to reduce 2,4-DNBA as well as 2-NBA. 2,4-DNBA is formed by photolysis of the explosive 2,4,6-trinitrotoluene (18). Some bacteria were able to degrade 2,4-DNBA in a nitroaromatic pesticide-contaminated environment (19).…”

Section: Discussionmentioning

confidence: 99%

2-Nitrobenzoate 2-Nitroreductase (NbaA) Switches Its Substrate Specificity from 2-Nitrobenzoic Acid to 2,4-Dinitrobenzoic Acid under Oxidizing Conditions

Kim

Song

et al. 2013

J Bacteriol

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e 2-Nitrobenzoate 2-nitroreductase (NbaA) of Pseudomonas fluorescens strain KU-7 is a unique enzyme, transforming 2-nitrobenzoic acid (2-NBA) and 2,4-dinitrobenzoic acid (2,4-DNBA) to the 2-hydroxylamine compounds. Sequence comparison reveals that NbaA contains a conserved cysteine residue at position 141 and two variable regions at amino acids 65 to 74 and 193 to 216. The truncated mutant ⌬65-74 exhibited markedly reduced activity toward 2,4-DNBA, but its 2-NBA reduction activity was unaffected; however, both activities were abolished in the ⌬193-216 mutant, suggesting that these regions are necessary for the catalysis and specificity of NbaA. NbaA showed different lag times for the reduction of 2-NBA and 2,4-DNBA with NADPH, and the reduction of 2,4-DNBA, but not 2-NBA, failed in the presence of 1 mM dithiothreitol or under anaerobic conditions, indicating oxidative modification of the enzyme for 2,4-DNBA. The enzyme was irreversibly inhibited by 5,5=-dithio-bis-(2-nitrobenzoic acid) and ZnCl 2 , which bind to reactive thiol/thiolate groups, and was eventually inactivated during the formation of higherorder oligomers at high pH, high temperature, or in the presence of H 2 O 2 . SDS-PAGE and mass spectrometry revealed the formation of intermolecular disulfide bonds by involvement of the two cysteines at positions 141 and 194. Site-directed mutagenesis indicated that the cysteines at positions 39, 103, 141, and 194 played a role in changing the enzyme activity and specificity toward 2-NBA and 2,4-DNBA. This study suggests that oxidative modifications of NbaA are responsible for the differential specificity for the two substrates and further enzyme inactivation through the formation of disulfide bonds under oxidizing conditions.

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“…The photolysis rate in the live river water was lower than that in killed river water. This may be due to the sequestration of 1-AP by the living systems in the solution (21).…”

Section: Photolysis Of 1-ap In Different Aqueous Solutionsmentioning

confidence: 99%

A Study of Photoinduced Toxicity of 1-Aminopyrene (1-AP) to Microbial Assemblages and the Effect of Humic Substances on 1-AP Photolysis

Hwang

Zeng

Dong

et al. 2002

Polycyclic Aromatic Compounds

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Two sources of humic acid (HA) were added to a phosphate-buffered solution to determine the effect of HA on 1-aminopyrene (1-AP) photolysis rate under UV-A irradiation and natural solar irradiation. Microbial assemblages in a river water sample were used to determine the ecotoxicity of 1-AP and its photoproducts. The microbial bioassay includes spread plate counting and microbial mineralization of 14 C-D-glucose, succinate, and citrate. At 1-AP concentration of 8 µM, bacterial viability was not affected and heterotrophic activities were inhibited by 41% to 63% after exposure for 24 hr. Exposure to 1-AP photoproducts inhibited bacterial viability and heterotrophic activities by 58% and 77% to 84%, respectively. Therefore, photoinduced toxicity of 1-AP to microbial assemblages was observed in this study. With additions of HA at concentrations of 10-80 ppm, the photolysis rate constants of 1-AP (10 µM) in

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Effect of photosensitizer riboflavin on the fate of 2,4,6-trinitrotoluene in a freshwater environment

Cited by 39 publications

References 8 publications

Phototransformation of 2,4,6-trinitrotoluene: Sensitized by riboflavin under different irradiation spectral range

Phototransformation of 2,4,6-trinitrotoluene: Sensitized by riboflavin under different irradiation spectral range

2-Nitrobenzoate 2-Nitroreductase (NbaA) Switches Its Substrate Specificity from 2-Nitrobenzoic Acid to 2,4-Dinitrobenzoic Acid under Oxidizing Conditions

A Study of Photoinduced Toxicity of 1-Aminopyrene (1-AP) to Microbial Assemblages and the Effect of Humic Substances on 1-AP Photolysis

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