Anaerobic Removal of Pentachlorophenol in Presence of Zinc

Jin, Peikang; Bhattacharya, Sanjoy K.

doi:10.1061/(asce)0733-9372(1996)122:7(590)

Cited by 17 publications

(9 citation statements)

References 19 publications

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“…In complex media, it is difficult to calculate the concentrations of all components because the composition of complex ingredients (e.g., yeast extract, beef extract) differs slightly in every batch. At least three computational models have been developed to predict the impact of metals on organic biodegradation [14,41,96]. None of these models incorporates metal speciation and bioavailability.…”

Section: Measurement Of Bioavailable Metal Concentrationmentioning

confidence: 99%

Bioavailability of Heavy Metals in Soil: Impact on Microbial Biodegradation of Organic Compounds and Possible Improvement Strategies

Olaniran

Balgobind

Pillay

2013

IJMS

515

197

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Co-contamination of the environment with toxic chlorinated organic and heavy metal pollutants is one of the major problems facing industrialized nations today. Heavy metals may inhibit biodegradation of chlorinated organics by interacting with enzymes directly involved in biodegradation or those involved in general metabolism. Predictions of metal toxicity effects on organic pollutant biodegradation in co-contaminated soil and water environments is difficult since heavy metals may be present in a variety of chemical and physical forms. Recent advances in bioremediation of co-contaminated environments have focussed on the use of metal-resistant bacteria (cell and gene bioaugmentation), treatment amendments, clay minerals and chelating agents to reduce bioavailable heavy metal concentrations. Phytoremediation has also shown promise as an emerging alternative clean-up technology for co-contaminated environments. However, despite various investigations, in both aerobic and anaerobic systems, demonstrating that metal toxicity hampers the biodegradation of the organic component, a paucity of information exists in this area of research. Therefore, in this review, we discuss the problems associated with the degradation of chlorinated organics in co-contaminated environments, owing to metal toxicity and shed light on possible improvement strategies for effective bioremediation of sites co-contaminated with chlorinated organic compounds and heavy metals.

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Section: Measurement Of Bioavailable Metal Concentrationmentioning

confidence: 99%

Bioavailability of Heavy Metals in Soil: Impact on Microbial Biodegradation of Organic Compounds and Possible Improvement Strategies

Olaniran

Balgobind

Pillay

2013

IJMS

515

197

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show abstract

“…At least three computational models have been developed to predict the impact of metals on organic biodegradation (Amor et al 2001;Jin and Bhattacharya 1996;Nakamura and Sawada 2000). These models account for metal inhibition by adding metal inhibition constants (e.g., K i ) to conventional growth and/or degradation equations.…”

Section: Review | Metals and The Biodegradation Of Organic Pollutantsmentioning

confidence: 99%

Impact of metals on the biodegradation of organic pollutants.

Sandrin

Maier

2003

Environ Health Perspect

333

179

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Forty percent of hazardous waste sites in the United States are co-contaminated with organic and metal pollutants. Data from both aerobic and anaerobic systems demonstrate that biodegradation of the organic component can be reduced by metal toxicity. Metal bioavailability, determined primarily by medium composition/soil type and pH, governs the extent to which metals affect biodegradation. Failure to consider bioavailability rather than total metal likely accounts for much of the enormous variability among reports of inhibitory concentrations of metals. Metals appear to affect organic biodegradation through impacting both the physiology and ecology of organic degrading microorganisms. Recent approaches to increasing organic biodegradation in the presence of metals involve reduction of metal bioavailability and include the use of metal-resistant bacteria, treatment additives, and clay minerals. The addition of divalent cations and adjustment of pH are additional strategies currently under investigation.

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“…Uncompetitive inhibition by itself is a rare phenomenon in enzyme kinetics,27 although the mixed-type competitive-uncompetitive inhibition is quite common 28,29. On the other hand, the parabolic mixed-type mechanism, which describes the binding of an inhibitor to two non-mutually exclusive sites, is very atypical 30.…”

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confidence: 99%

Solution Kinetics Measurements Suggest HIV-1 Protease Has Two Binding Sites for Darunavir and Amprenavir

Kovalevsky

Ghosh²,

Weber³

2008

J. Med. Chem.

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Darunavir, a potent antiviral drug, showed an unusual second binding site on the HIV-1 protease dimer surface of the V32I drug resistant mutant and normal binding in the active site cavity. Kinetic analysis for wild type and mutant protease showed mixed-type competitive-uncompetitive inhibition for darunavir and the chemically related amprenavir, while saquinavir showed competitive inhibition. The inhibition model is consistent with the observed second binding site for darunavir and helps to explain its antiviral potency.HIV-1 protease (PR) has been the target of intensive research for the past two decades that has led to effective drugs for the treatment of HIV/AIDS, i.e. small molecule synthetic protease inhibitors (PIs). 1 The PIs have become the paradigm for successful structure-assisted drug design, 2 with nine PIs now approved by the FDA for AIDS therapy. The addition of PIs to the antiviral regimens resulted in highly increased survival rates and lower morbidity caused by the disease in the past decade. However, the emergence of drug-resistant HIV has necessitated the recent development of PIs, such as darunavir (DRV) designed to target PR mutants. 3,4 DRV has proved highly effective in salvage therapy for patients failing other treatments. 5 Success of the design strategy was verified by crystallographic and kinetic analysis of DRV with HIV-1 protease and its mutants. 6,7,8,9,10 The clinical PIs have been designed to inhibit the activity of the HIV-1 PR by competitively binding inside the active-site cavity, 11,12,13 which is formed by a dimer of two identical 99-residue subunits. Numerous crystal structures of HIV-1 PR complexed with different PIs have shown exclusive binding of the inhibitors in the active-site cavity. Some reversible inhibitor molecules, like beta-lactam compounds 14 and Nb-containing polyoxometalates 15 , were proposed to bind on the surface of the enzyme in uncompetitive or non-competitive manner, respectively, rather than in the usual active site cavity. Also, irreversible inhibitors like haloperidol analogues 16 and Cu 2+ ions 7 can disrupt the HIV-1 PR activity by attaching covalently at surface sites. One peptide inhibitor was observed to bind on the protein surface between PR dimers in the crystal lattice, although this inhibitor showed no specific interactions with PR. 17 An unusual second binding site for DRV was observed in the two high-resolution crystal structures of complexes with HIV-1 PR mutants with the single substitutions of V32I (0.84 Å) # to whom correspondence should be addressed. and M46L (1.22 Å). 18 In both structures one inhibitor molecule occupied the active-site cavity, while the other inhibitor molecule was located in a deep groove on the PR surface in the flap region. Thus the PR/DRV 2 species was observed in the solid state ( Figure 1a). The surfacebound inhibitor molecule formed a number of specific interactions with the mutant PR residues, including hydrogen bonds (Figure 1b), C-H…O and C-H…π contacts, unlike the peptide observed on the flap sur...

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Anaerobic Removal of Pentachlorophenol in Presence of Zinc

Cited by 17 publications

References 19 publications

Bioavailability of Heavy Metals in Soil: Impact on Microbial Biodegradation of Organic Compounds and Possible Improvement Strategies

Bioavailability of Heavy Metals in Soil: Impact on Microbial Biodegradation of Organic Compounds and Possible Improvement Strategies

Impact of metals on the biodegradation of organic pollutants.

Solution Kinetics Measurements Suggest HIV-1 Protease Has Two Binding Sites for Darunavir and Amprenavir

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