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Greener Synthesis of Natural Products
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
Renata Kołodziejska, Renata Studzińska, Hanna Pawluk, Alina Woźniak
The next group of enzymes willingly used in asymmetric synthesis is oxidoreductases. Oxidoreductases include, among others: oxidases, hydroperoxidases, peroxidases, catalases, oxygenases, hydroxylases, dehydrogenases, and reductases. Of the oxidoreductases, dehydrogenases are particularly explored, which oxidize primary and secondary alcohols and reduce the carbonyl double bond to form an alcohol moiety. Oxygenases to carry out the reaction need oxygen as a co-substrate, catalyze the oxidation reactions of C-H and C=C binding, belong to the second important subgroup of oxidoreductases used in asymmetric synthesis. They are divided into dioxygenases, which incorporate two oxygen atoms into the substrate, and monooxygenases catalyze the incorporation of one oxygen atom into the hydroxylated substrate. In contrast, oxidases, enzymes that catalyze the transfer of hydrogen to oxygen, resulting in the formation of water or hydrogen peroxide, and reductases, which reduce olefins to alkanes, are used to a small extent in biosynthesis.
Role of Enzymes in the Bioremediation of Refractory Pollutants
Published in Maulin P. Shah, Removal of Refractory Pollutants from Wastewater Treatment Plants, 2021
Viresh R. Thamke, Ashvini U. Chaudhari, Kisan M. Kodam, Jyoti P. Jadhav
Dioxygenase degrades aromatic pollutants by adding two atoms of an oxygen molecule in the ring [Figure 1(D)]. The aromatic dioxygenases are classified according to their mode of action as aromatic ring hydroxylation dioxygenase (ARHDs) and aromatic ring cleavage dioxygenase (ARCDs). The ARHDs degrade aromatic compounds by adding two molecules of oxygen into the ring, whereas ARCDs break aromatic rings of compounds. The catechol dioxygenases that are found in the soil bacteria cause the biotransformation of aromatic precursors into aliphatic products (Muthukamalam et al. 2017). Toluene dioxygenase (TOD) catalyzes the first reaction in the degradation of toluene. This multi-component enzyme system acts on the broad substrate and behaves as monooxygenase and dioxygenase. TOD also has the ability to catalyze sulfoxidation reactions and convert ethyl phenyl sulfide, methyl phenyl sulfide, methyl p-nitrophenyl sulfide, and p-methoxymethyl sulfide into their respective sulfoxides. TOD also detoxifies polychlorinated hydrocarbons, chlorotoluenes, and BTEX residues very effectively (Scott et al. 2008).
Global Environmental Issues and the Role of Nanobiotechnology for the Sustainable Environment
Published in Amit Kumar, Chhotu Ram, Nanobiotechnology for Green Environment, 2021
Chhotu Ram, Amit Kumar, Yilkal Bezie
The oxidoreductases perform humification of different phenolic compounds that are generated from the decomposition of lignin in the soil environment. Similarly, oxidoreductases can also detoxify toxic xenobiotic substances such as phenolic or anilinic compounds polymerization, copolymerization with other substrates, or binding to humic substances (Karigar and Rao, 2011; Park et al., 2006). Oxygenases are the oxidoreductases that perform the oxidation of reduced substances by utilizing oxygen from molecular oxygen and FAD/NADH, NADPH as a co-substrate. Oxygenases are categorized into two groups (monooxygenases and dioxygenases) based on the number of oxygen atoms used for oxygenation (Arora et al., 2009; Karigar and Rao, 2011). Mono-oxygenases incorporate one atom of oxygen into the substrate; whereas, dioxygenases add both atoms of oxygen to a substrate. Mono-oxygenases are grouped into flavin-dependent mono-oxygenases and P450 mono-oxygenases, based on the co-factor requirement (Arora et al., 2010) (Table 1.2). Dioxygenases are a multicomponent enzyme system that incorporates oxygen into the substrate. Dioxygenases primarily oxidize aromatic compounds and therefore are applicable in environmental remediation (Karigar and Rao, 2011).
Evaluation of biphenyl- and polychlorinated-biphenyl (PCB) degrading Rhodococcus sp. MAPN-1 on growth of Morus alba by pot study
Published in International Journal of Phytoremediation, 2020
Monika Sandhu, Prameela Jha, Atish T. Paul, Rajnish P. Singh, Prabhat N. Jha
It is universally accepted that various PCB congeners can be co-metabolized by biphenyl degrading bacteria through the biphenyl catabolic pathway. These enzymes are encoded by genes included in biphenyl operon and are marked as bph genes (Ionescu et al. 2009; Li et al. 2009; Chang et al. 2013; Dudášová et al. 2014). Aerobic biphenyl catabolic pathway includes biphenyl upper pathway and lower pathway. Biphenyl upper pathway involves catabolism of biphenyl into benzoate or PCBs into chlorobenzoates which led to further mineralization. Several reports on the characterization of the genes and PCB degrading activity involved therein indicate the potential of some aerobic and anaerobic bacteria such as Pseudomonas, Rhodococcus, Ochrobactrum, Achromobacter, Alcaligenes, Burkholderia, and Ralstonia, among others (Abramowicz 1990; Bokvajová et al. 1994; Murínová et al. 2014; Passatore et al. 2014). The enzymes involved in biphenyl degradation are similar in all aerobic bacteria. Dioxygenase has versatile substrate specificity, and thus it allows degradation of biphenyl and its related compounds such as benzene polyaromatic hydrocarbons. Therefore, the recovery of isolates that are representative of the microorganisms responsible for the bioremediation process can be invaluable because studying these isolates provides the opportunity to investigate not only their biodegradation reactions but also other aspects of their physiology that are likely to control their growth and activity in contaminated environments.
Evaluation of the effect of cold atmospheric plasma on oxygenases’ activities for application in water treatment technologies
Published in Environmental Technology, 2019
Yovana Todorova, Ivaylo Yotinov, Yana Topalova, Evgenia Benova, Plamena Marinova, Ivan Tsonev, Todor Bogdanov
The biological transformation of aromatic hydrocarbons is mainly an aerobic process and proceeds through a few key intermediates, such as catechols, protocatechuates and gentisates. The crucial step is the incorporation of molecular oxygen as hydroxyl group by phenol 2-monooxygenase enzymes, followed by ring cleavage with the key participation of dioxygenases [2,34,35]. Phenol 2-monooxygenases vary in different microorganisms from simple flavoprotein monooxygenases to multicomponent monooxygenases [36]. Dioxygenases are metalloenzymes, divided into two classes: intradiol dioxygenases with cleavage target – ortho-position to the hydroxyl substituent and extradiol dioxygenases which cleave on meta-position. Ortho-pathway represents the oxidation of catechol to cis, cis-muconate in a reaction catalyzed by catechol 1,2-dioxygenase (C12DO), and meta-pathway is the oxidation of catechol to 2-hydroxymuconic semialdehyde in a reaction catalyzed by catechol 2,3-dioxygenase (C23DO). In some cases, catechol is transformed to protocatechuate and cleavage of the benzene ring is carried out by protocatechuate 3,4-dioxygenase (P34DO), with the product β-carboxy-cis, cis-muconate. It has been proven that all intradiol dioxygenases have a significant homology and share a common tertiary fold. The initial coordination geometry is trigonal-bipyramidal with non-heme ferric ion ligated to one tyrosine, one histidine and abound hydroxyl in the equatorial plane, and the second tyrosine and histidine as axial ligands [37,38].
The fate and enhanced removal of polycyclic aromatic hydrocarbons in wastewater and sludge treatment system: A review
Published in Critical Reviews in Environmental Science and Technology, 2019
Xiaoyang Zhang, Tong Yu, Xu Li, Junqin Yao, Weiguo Liu, Shunli Chang, Yinguang Chen
The mechanism of aerobic biodegradation of PAHs is that dioxygenase enzymes initially oxidize the benzene rings of PAHs for the formation of cis-dihydrodiols (Alegbeleye et al., 2017), which are bio-converted to dihydroxylated intermediates by dehydrogenation and ended with CO2 and H2O productions (Bamforth & Singleton, 2005; Habe & Omori, 2003; Wick, Haus, Sukkariyah, Haering, & Daniels, 2011). As shown in Figure 2, not only bacteria, belonging to genera Mycobacterium, Polaromonas, Pseudomonas, Ralstonia, Rhodococcus, and Sphingomonas, but also fungal species, especially the White Rot Fungi group (such as Phanerochaete chrysosporium, Bjerkandera adusta and Pleurotus ostreatus) can efficiently eliminate PAHs by biodegradation under aerobic conditions (Haritash & Kaushik, 2009; Pozdnyakova, 2012; Seo, Keum, & Li, 2009). Bacteria can use NAP as the only source of carbon and energy (Seo et al., 2009), while fungi generate extracellular lignin-degrading enzymes with low specificity for substrate, which enhances their ability to degrade PAHs (Gan et al., 2009; Haritash & Kaushik, 2009) since extracellular polymeric substances (EPS) from fungi are more effective in biodegradation of PAHs than those from bacterium (Jia et al., 2017).