A Novel Mechanism for Azoreduction

Ryan, Ali; Laurieri, Nicola; Westwood, Isaac M.; Wang, Chan Ju; Lowe, E.D.; Sim, Edith

doi:10.1016/j.jmb.2010.04.023

Cited by 52 publications

(84 citation statements)

References 74 publications

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“…Two broad types of azoreductases including flavin-dependent and non-flavin reductases have been reported (Blumel & Stolz, 2003;Maier et al, 2004;Suzuki et al, 2001). Flavin-dependent azoreductases usually reduce azo dyes through a Ping-Pong Bi-Bi mechanism (Nakanishi et al, 2001;Ryan et al, 2010;Wang et al, 2010). In this mechanism, two cycles of NADPH-dependent reduction of FMN to FMNH occur, converting azo dye to a hydrazine in the first step, and then the hydrazine to two constitutive amines in the second step (Correia et al, 2011;Ryan et al, 2010).…”

Section: Reductive Enzymesmentioning

confidence: 99%

“…Flavin-dependent azoreductases usually reduce azo dyes through a Ping-Pong Bi-Bi mechanism (Nakanishi et al, 2001;Ryan et al, 2010;Wang et al, 2010). In this mechanism, two cycles of NADPH-dependent reduction of FMN to FMNH occur, converting azo dye to a hydrazine in the first step, and then the hydrazine to two constitutive amines in the second step (Correia et al, 2011;Ryan et al, 2010). Flavin dependent azoreductases are polymeric in nature, and flavin molecules are non-covalently attached with protein and link the dimeric sub units of azoreductases (Liger et al, 2004).…”

Section: Reductive Enzymesmentioning

confidence: 99%

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Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

Ibekwe

Yang

et al. 2016

Science of The Total Environment

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Azo dyes and their intermediate degradation products are common contaminants of soil and groundwater in developing countries where textile and leather dye products are produced. The toxicity of azo dyes is primarily associated with their molecular structure, substitution groups and reactivity. To avoid contamination of natural resources and to minimize risk to human health, this wastewater requires treatment in an environmentally safe manner. This manuscript critically reviews biological treatment systems and the role of bacterial reductive and oxidative enzymes/processes in the bioremediation of dye-polluted wastewaters. Many studies have shown that a variety of culturable bacteria have efficient enzymatic systems that can carry out complete mineralization of dye chemicals and their metabolites (aromatic compounds) over a wide range of environmental conditions. Complete mineralization of azo dyes generally involves a two-step process requiring initial anaerobic treatment for decolorization, followed by an oxidative process that results in degradation of the toxic intermediates that are formed during the first step. Molecular studies have revealed that the first reductive process can be carried out by two classes of enzymes involving flavin-dependent and flavin-free azoreductases under anaerobic or low oxygen conditions. The second step that is carried out by oxidative enzymes that primarily involves broad specificity peroxidases, laccases and tyrosinases. This review focuses, in particular, on the characterization of these enzymes with respect to their enzyme kinetics and the environmental conditions that are necessary for bioreactor systems to treat azo dyes contained in wastewater.

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Section: Reductive Enzymesmentioning

confidence: 99%

Section: Reductive Enzymesmentioning

confidence: 99%

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

Ibekwe

Yang

et al. 2016

Science of The Total Environment

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“…1A) (Ryan et al, 2010). The first reduction reaction is proposed to be followed by cleavage of the hydrazine intermediate via an acid or base catalyzed reaction (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism for azo reduction that has been proposed (Ryan et al, 2010) explains the ability of azoreductases to reduce both azo and quinone substrates. It has been suggested that the major biological role of azoreductases is in the detoxification of quinones (Liu et al, 2008(Liu et al, , 2009.…”

Section: Introductionmentioning

confidence: 99%

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Reaction mechanism of azoreductases suggests convergent evolution with quinone oxidoreductases

et al. 2010

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Azoreductases are involved in the bioremediation by bacteria of azo dyes found in waste water. In the gut flora, they activate azo pro-drugs, which are used for treatment of inflammatory bowel disease, releasing the active component 5-aminosalycilic acid. The bacterium P. aeruginosa has three azoreductase genes, paAzoR1, paAzoR2 and paAzoR3, which as recombinant enzymes have been shown to have different substrate specificities. The mechanism of azoreduction relies upon tautomerisation of the substrate to the hydrazone form. We report here the characterization of the P. aeruginosa azoreductase enzymes, including determining their thermostability, cofactor preference and kinetic constants against a range of their favoured substrates. The expression levels of these enzymes during growth of P. aeruginosa are altered by the presence of azo substrates. It is shown that enzymes that were originally described as azoreductases, are likely to act as NADH quinone oxidoreductases. The low sequence identities observed among NAD(P)H quinone oxidoreductase and azoreductase enzymes suggests convergent evolution.

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In Vitro and Ex Vivo Dissolution Tests for Considering Dissolution in the Lower Intestine

Markopoulos

Vertzoni

2022

Oral Drug Delivery for Modified Release Formulations

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A Novel Mechanism for Azoreduction

Cited by 52 publications

References 74 publications

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

Reaction mechanism of azoreductases suggests convergent evolution with quinone oxidoreductases

In Vitro and Ex Vivo Dissolution Tests for Considering Dissolution in the Lower Intestine

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