Journal articles: 'Monooxygenase oxidation'

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Furuya, Toshiki, Mika Hayashi, and Kuniki Kino. "Reconstitution of Active Mycobacterial Binuclear Iron Monooxygenase Complex in Escherichia coli." Applied and Environmental Microbiology 79, no. 19 (July 26, 2013): 6033–39. http://dx.doi.org/10.1128/aem.01856-13.

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ABSTRACTBacterial binuclear iron monooxygenases play numerous physiological roles in oxidative metabolism. Monooxygenases of this type found in actinomycetes also catalyze various useful reactions and have attracted much attention as oxidation biocatalysts. However, difficulties in expressing these multicomponent monooxygenases in heterologous hosts, particularly inEscherichia coli, have hampered the development of engineered oxidation biocatalysts. Here, we describe a strategy to functionally express the mycobacterial binuclear iron monooxygenase MimABCD inEscherichia coli. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of themimABCDgene expression inE. colirevealed that the oxygenase components MimA and MimC were insoluble. Furthermore, although the reductase MimB was expressed at a low level in the soluble fraction ofE. colicells, a band corresponding to the coupling protein MimD was not evident. This situation rendered the transformedE. colicells inactive. We found that the following factors are important for functional expression of MimABCD inE. coli: coexpression of the specific chaperonin MimG, which caused MimA and MimC to be soluble inE. colicells, and the optimization of themimDnucleotide sequence, which led to efficient expression of this gene product. These two remedies enabled this multicomponent monooxygenase to be actively expressed inE. coli. The strategy described here should be generally applicable to theE. coliexpression of other actinomycetous binuclear iron monooxygenases and related enzymes and will accelerate the development of engineered oxidation biocatalysts for industrial processes.

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Koo, Christopher W., and Amy C. Rosenzweig. "Biochemistry of aerobic biological methane oxidation." Chemical Society Reviews 50, no. 5 (2021): 3424–36. http://dx.doi.org/10.1039/d0cs01291b.

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Methane monooxygenase enzymes use metal cofactors to activate methane under ambient, aerobic conditions. This review highlights recent progress in understanding the structure and activity of the membrane-bound and soluble methane monooxygenases.

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Kostichka, Kristy, Stuart M. Thomas, Katharine J. Gibson, Vasantha Nagarajan, and Qiong Cheng. "Cloning and Characterization of a Gene Cluster for Cyclododecanone Oxidation in Rhodococcus ruber SC1." Journal of Bacteriology 183, no. 21 (November 1, 2001): 6478–86. http://dx.doi.org/10.1128/jb.183.21.6478-6486.2001.

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ABSTRACT Biological oxidation of cyclic ketones normally results in formation of the corresponding dicarboxylic acids, which are further metabolized in the cell. Rhodococcus ruber strain SC1 was isolated from an industrial wastewater bioreactor that was able to utilize cyclododecanone as the sole carbon source. A reverse genetic approach was used to isolate a 10-kb gene cluster containing all genes required for oxidative conversion of cyclododecanone to 1,12-dodecanedioic acid (DDDA). The genes required for cyclododecanone oxidation were only marginally similar to the analogous genes for cyclohexanone oxidation. The biochemical function of the enzymes encoded on the 10-kb gene cluster, the flavin monooxygenase, the lactone hydrolase, the alcohol dehydrogenase, and the aldehyde dehydrogenase, was determined in Escherichia coli based on the ability to convert cyclododecanone. Recombinant E. colistrains grown in the presence of cyclododecanone accumulated lauryl lactone, 12-hydroxylauric acid, and/or DDDA depending on the genes cloned. The cyclododecanone monooxygenase is a type 1 Baeyer-Villiger flavin monooxygenase (FAD as cofactor) and exhibited substrate specificity towards long-chain cyclic ketones (C11 to C15), which is different from the specificity of cyclohexanone monooxygenase favoring short-chain cyclic compounds (C5 to C7).

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van Hylckama Vlieg, Johan E. T., Hans Leemhuis, Jeffrey H. Lutje Spelberg, and Dick B. Janssen. "Characterization of the Gene Cluster Involved in Isoprene Metabolism in Rhodococcus sp. Strain AD45." Journal of Bacteriology 182, no. 7 (April 1, 2000): 1956–63. http://dx.doi.org/10.1128/jb.182.7.1956-1963.2000.

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ABSTRACT The genes involved in isoprene (2-methyl-1,3-butadiene) utilization in Rhodococcus sp. strain AD45 were cloned and characterized. Sequence analysis of an 8.5-kb DNA fragment showed the presence of 10 genes of which 2 encoded enzymes which were previously found to be involved in isoprene degradation: a glutathioneS-transferase with activity towards 1,2-epoxy-2-methyl-3-butene (isoI) and a 1-hydroxy-2-glutathionyl-2-methyl-3-butene dehydrogenase (isoH). Furthermore, a gene encoding a second glutathioneS-transferase was identified (isoJ). TheisoJ gene was overexpressed in Escherichia coliand was found to have activity with 1-chloro-2,4-dinitrobenzene and 3,4-dichloro-1-nitrobenzene but not with 1,2-epoxy-2-methyl-3-butene. Downstream of isoJ, six genes (isoABCDEF) were found; these genes encoded a putative alkene monooxygenase that showed high similarity to components of the alkene monooxygenase fromXanthobacter sp. strain Py2 and other multicomponent monooxygenases. The deduced amino acid sequence encoded by an additional gene (isoG) showed significant similarity with that of α-methylacyl-coenzyme A racemase. The results are in agreement with a catabolic route for isoprene involving epoxidation by a monooxygenase, conjugation to glutathione, and oxidation of the hydroxyl group to a carboxylate. Metabolism may proceed by fatty acid oxidation after removal of glutathione by a still-unknown mechanism.

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Yamamoto, Taisei, Kento Kobayashi, Yoshie Hasegawa, and Hiroaki Iwaki. "Cloning, expression, and characterization of Baeyer–Villiger monooxygenases from eukaryotic Exophiala jeanselmei strain KUFI-6N." Bioscience, Biotechnology, and Biochemistry 85, no. 7 (April 30, 2021): 1675–85. http://dx.doi.org/10.1093/bbb/zbab079.

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ABSTRACT The fungus Exophiala jeanselmei strain KUFI-6N produces a unique cycloalkanone monooxygenase (ExCAMO) that displays an uncommon substrate spectrum of Baeyer–Villiger oxidation of 4-10-membered ring ketones. In this study, we aimed to identify and sequence the gene encoding ExCAMO from KUFI-6N and overexpress the gene in Escherichia coli. We found that the primary structure of ExCAMO is most closely related to the cycloalkanone monooxygenase from Cylindrocarpon radicicola ATCC 11011, with 54.2% amino acid identity. ExCAMO was functionally expressed in E. coli and its substrate spectrum and kinetic parameters were investigated. Substrate profiling indicated that ExCAMO is unusual among known Baeyer–Villiger monooxygenases owing to its ability to accept a variety of substrates, including C4-C12 membered ring ketones. ExCAMO has high affinity and catalytic efficiency toward cycloalkanones, the highest being toward cyclohexanone. Five other genes encoding Baeyer–Villiger monooxygenases were also cloned and expressed in E. coli.

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Brzostowicz, Patricia C., Dana M. Walters, Stuart M. Thomas, Vasantha Nagarajan, and Pierre E. Rouvière. "mRNA Differential Display in a Microbial Enrichment Culture: Simultaneous Identification of Three Cyclohexanone Monooxygenases from Three Species." Applied and Environmental Microbiology 69, no. 1 (January 2003): 334–42. http://dx.doi.org/10.1128/aem.69.1.334-342.2003.

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ABSTRACT mRNA differential display has been used to identify cyclohexanone oxidation genes in a mixed microbial community derived from a wastewater bioreactor. Thirteen DNA fragments randomly amplified from the total RNA of an enrichment subculture exposed to cyclohexanone corresponded to genes predicted to be involved in the degradation of cyclohexanone. Nine of these DNA fragments are part of genes encoding three distinct Baeyer-Villiger cyclohexanone monooxygenases from three different bacterial species present in the enrichment culture. In Arthrobacter sp. strain BP2 and Rhodococcus sp. strain Phi2, the monooxygenase is part of a gene cluster that includes all the genes required for the degradation of cyclohexanone, while in Rhodococcus sp. strain Phi1 the genes surrounding the monooxygenase are not predicted to be involved in this degradation pathway but rather seem to belong to a biosynthetic pathway. Furthermore, in the case of Arthrobacter strain BP2, three other genes flanking the monooxygenase were identified by differential display, demonstrating that the repeated sampling of bacterial operons shown earlier for a pure culture (D. M. Walters, R. Russ, H. Knackmuss, and P. E. Rouvière, Gene 273:305-315, 2001) is also possible for microbial communities. The activity of the three cyclohexanone monooxygenases was confirmed and characterized following their expression in Escherichia coli.

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Willetts, Andrew. "The Isoenzymic Diketocamphane Monooxygenases of Pseudomonas putida ATCC 17453—An Episodic History and Still Mysterious after 60 Years." Microorganisms 9, no. 12 (December 15, 2021): 2593. http://dx.doi.org/10.3390/microorganisms9122593.

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Researching the involvement of molecular oxygen in the degradation of the naturally occurring bicyclic terpene camphor has generated a six-decade history of fascinating monooxygenase biochemistry. While an extensive bibliography exists reporting the many varied studies on camphor 5-monooxygenase, the initiating enzyme of the relevant catabolic pathway in Pseudomonas putida ATCC 17453, the equivalent recorded history of the isoenzymic diketocamphane monooxygenases, the enzymes that facilitate the initial ring cleavage of the bicyclic terpene, is both less extensive and more enigmatic. First referred to as ‘ketolactonase—an enzyme for cyclic lactonization’—the enzyme now classified as 2,5-diketocamphane 1,2-monooxygenase (EC 1.14.14.108) holds a special place in the history of oxygen-dependent biochemistry, being the first biocatalyst confirmed to undertake a biooxygenation reaction equivalent to the peracid-catalysed Baeyer–Villiger chemical oxidation first reported in the late 19th century. However, following that auspicious beginning, the biochemistry of EC 1.14.14.108, and its isoenzymic partner 3,6-diketocamphane 1,6-monooxygenase (EC 1.14.14.155) was dogged for many years by the mistaken belief that the enzymes were true flavoproteins that function with a tightly-bound flavin cofactor in the active site. This misconception led to a number of erroneous interpretations of relevant experimental data. It is only in the last decade, initially as the result of pure serendipity, that these enzymes have been confirmed to be members of a relatively recently discovered class of oxygen-dependent enzymes, the flavin-dependent two-component monooxygenases. This has promoted a renaissance of interest in the enzymes, resulting in programmes of research that have significantly expanded current knowledge of both their mode of action and regulation in camphor-grown P. putida ATCC 17453. However, some features of the biochemistry of the isoenzymic diketocamphane monooxygenases remain currently unexplained. It is the episodic history of these enzymes and some of what remains unresolved that are the principal subjects of this review.

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Brzostowicz, Patricia C., Katharine L. Gibson, Stuart M. Thomas, Mary Sue Blasko, and Pierre E. Rouvière. "Simultaneous Identification of Two Cyclohexanone Oxidation Genes from an Environmental Brevibacterium Isolate Using mRNA Differential Display." Journal of Bacteriology 182, no. 15 (August 1, 2000): 4241–48. http://dx.doi.org/10.1128/jb.182.15.4241-4248.2000.

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ABSTRACT The technique of mRNA differential display was used to identify simultaneously two metabolic genes involved in the degradation of cyclohexanone in a new halotolerant Brevibacteriumenvironmental isolate. In a strategy based only on the knowledge that cyclohexanone oxidation was inducible in this strain, the mRNA population of cells exposed to cyclohexanone was compared to that of control cells using reverse transcription-PCR reactions primed with a collection of 81 arbitrary oligonucleotides. Three DNA fragments encoding segments of flavin monooxygenases were isolated with this technique, leading to the identification of the genes of two distinct cyclohexanone monooxygenases, the enzymes responsible for the oxidation of cyclohexanone. Each monooxygenase was expressed in Escherichia coli and characterized. This work validates the application of mRNA differential display for the discovery of new microbial metabolic genes.

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Brantner, Christine A., Lorie A. Buchholz, Claudia L. McSwain, Laura L. Newcomb, Charles C. Remsen, and Mary Lynne Perille Collins. "Intracytoplasmic membrane formation in Methylomicrobium album BG8 is stimulated by copper in the growth medium." Canadian Journal of Microbiology 43, no. 7 (July 1, 1997): 672–76. http://dx.doi.org/10.1139/m97-095.

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Methylomicrobium album BG8 uses methane as its sole source of carbon and energy. The oxidation of methane to methanol is catalyzed by the enzyme methane monooxygenase. Methane monooxygenase activity, intracytoplasmic membrane abundance, and cell mass increased with increasing copper concentration in the medium. When copper was added to copper-deficient cultures, cell mass and intracytoplasmic membrane structure increased. These findings are consistent with the presence of copper in the particulate methane monooxygenase. Methane monooxygenase activity and intracytoplasmic membrane abundance were correlated, suggesting that the methane monooxygenase may be involved in intracytoplasmic membrane proliferation.Key words: Methylomicrobium album BG8, copper, intracytoplasmic membrane, methane monooxygenase.

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Hamamura, Natsuko, Ryan T. Storfa, Lewis Semprini, and Daniel J. Arp. "Diversity in Butane Monooxygenases among Butane-Grown Bacteria." Applied and Environmental Microbiology 65, no. 10 (October 1, 1999): 4586–93. http://dx.doi.org/10.1128/aem.65.10.4586-4593.1999.

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ABSTRACT Butane monooxygenases of butane-grown Pseudomonas butanovora, Mycobacterium vaccae JOB5, and an environmental isolate, CF8, were compared at the physiological level. The presence of butane monooxygenases in these bacteria was indicated by the following results. (i) O2 was required for butane degradation. (ii) 1-Butanol was produced during butane degradation. (iii) Acetylene inhibited both butane oxidation and 1-butanol production. The responses to the known monooxygenase inactivator, ethylene, and inhibitor, allyl thiourea (ATU), discriminated butane degradation among the three bacteria. Ethylene irreversibly inactivated butane oxidation by P. butanovora but not by M. vaccae or CF8. In contrast, butane oxidation by only CF8 was strongly inhibited by ATU. In all three strains of butane-grown bacteria, specific polypeptides were labeled in the presence of [14C]acetylene. The [14C]acetylene labeling patterns were different among the three bacteria. Exposure of lactate-grown CF8 and P. butanovora and glucose-grownM. vaccae to butane induced butane oxidation activity as well as the specific acetylene-binding polypeptides. Ammonia was oxidized by all three bacteria. P. butanovora oxidized ammonia to hydroxylamine, while CF8 and M. vaccae produced nitrite. All three bacteria oxidized ethylene to ethylene oxide. Methane oxidation was not detected by any of the bacteria. The results indicate the presence of three distinct butane monooxygenases in butane-grown P. butanovora, M. vaccae, and CF8.

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Shteinman, A. A. "Biomimetic alkane oxidation: Modelling methane monooxygenase." Journal of Inorganic Biochemistry 59, no. 2-3 (August 1995): 408. http://dx.doi.org/10.1016/0162-0134(95)97506-l.

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Zografos, Alexandros, and Marina Petsi. "Advances in Catalytic Aerobic Oxidations by Activation of Dioxygen-Monooxygenase Enzymes and Biomimetics." Synthesis 50, no. 24 (October 15, 2018): 4715–45. http://dx.doi.org/10.1055/s-0037-1610297.

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Monooxygenases are not only some of the most versatile machineries in our lives, but also some of the most explored enzymes in modern organic synthesis. They provide knowledge and inspiration on how the most abandoned oxidant, dioxygen, can be activated and utilized to deliver selective oxidations. This review presents an outline in the mechanisms that Nature uses to succeed in these processes and recent indicative examples on how chemists use this knowledge to develop selective oxidation protocols based on dioxygen as the terminal oxidant.1 Introduction2 Monooxygenases2.1 Metal-Based Monooxygenases2.1.1 Cytochromes2.1.2 Copper-Dependent Monooxygenases2.1.3 Heme-Independent Iron Monooxygenases2.1.4 Pterin-Dependent Monooxygenases2.2 Metal-Free Monooxygenases2.2.1 Flavin-Dependent Monooxygenases2.2.2 Systems without Cofactors3 Biomimetic Aerobic Oxidations3.1 Aerobic Oxidations Based on Metal Catalysts3.1.1 Epoxidations and Allylic Oxidations3.1.2 Oxidations of Unactivated Carbon Atoms and Benzylic Oxidations3.1.3 Oxidations of Aryl Groups3.1.4 Heteroatom Oxidations3.2 Aerobic Oxidations Based on Organocatalysts3.2.1 Baeyer–Villiger Oxidations3.2.2 Oxidations of Aryl Groups3.2.3 Heteroatom Oxidations4 Conclusion

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Petkevičius, Vytautas, Justas Vaitekūnas, Dovydas Vaitkus, Narimantas Čėnas, and Rolandas Meškys. "Tailoring a Soluble Diiron Monooxygenase for Synthesis of Aromatic N-oxides." Catalysts 9, no. 4 (April 12, 2019): 356. http://dx.doi.org/10.3390/catal9040356.

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The aromatic N-oxides have received increased attention over the last few years due to their potential application in medicine, agriculture and organic chemistry. As a green alternative in their synthesis, the biocatalytic method employing whole cells of Escherichia coli bearing phenol monooxygenase like protein PmlABCDEF (from here on – PML monooxygenase) has been introduced. In this work, site-directed mutagenesis was used to study the contributions of active site neighboring residues I106, A113, G109, F181, F200, F209 to the regiospecificity of N-oxidation. Based on chromogenic indole oxidation screening, a collection of PML mutants with altered catalytic properties was created. Among the tested mutants, the A113G variant acquired the most distinguishable N-oxidations capacity. This new variant of PML was able to produce dioxides (quinoxaline-1,4-dioxide, 2,5-dimethylpyrazine-1,4-dioxide) and specific mono-N-oxides (2,3,5-trimethylpyrazine-1-oxide) that were unachievable using the wild type PML. This mutant also featured reshaped regioselectivity as N-oxidation shifted towards quinazoline-1-oxide compared to quinazoline-3-oxide that is produced by the wild type PML.

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Perez-Paramo, Yadira X., Gang Chen, Joseph H. Ashmore, Christy J. W. Watson, Shamema Nasrin, Jennifer Adams-Haduch, Renwei Wang, et al. "Nicotine-N′-Oxidation by Flavin Monooxygenase Enzymes." Cancer Epidemiology Biomarkers & Prevention 28, no. 2 (October 31, 2018): 311–20. http://dx.doi.org/10.1158/1055-9965.epi-18-0669.

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Colonna, Stefano, Vincenza Pironti, Piero Pasta, and Francesca Zambianchi. "Oxidation of amines catalyzed by cyclohexanone monooxygenase." Tetrahedron Letters 44, no. 4 (January 2003): 869–71. http://dx.doi.org/10.1016/s0040-4039(02)02427-9.

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Secundo, Francesco, Giacomo Carrea, Sabrina Dallavalle, and Giuliana Franzosi. "Asymmetric oxidation of sulfides by cyclohexanone monooxygenase." Tetrahedron: Asymmetry 4, no. 9 (January 1993): 1981–82. http://dx.doi.org/10.1016/s0957-4166(00)82244-2.

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Wilkins, P. C., M. Fontecave, N. Deighton, I. Podmore, M. C. R. Symons, and H. Dalton. "Mechanism of substrate oxidation by methane monooxygenase." Journal of Inorganic Biochemistry 43, no. 2-3 (August 1991): 526. http://dx.doi.org/10.1016/0162-0134(91)84501-y.

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Guo, Can-Cheng, Xiao-Qin Liu, Qiang Liu, Yang Liu, Ming-Fu Chu, and Wei-Ying Lin. "First industrial-scale biomimetic oxidation of hydrocarbon with air over metalloporphyrins as cytochrome P-450 monooxygenase model and its mechanistic studies." Journal of Porphyrins and Phthalocyanines 13, no. 12 (December 2009): 1250–54. http://dx.doi.org/10.1142/s1088424609001613.

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A novel industrial-scale trial for cyclohexane oxidation with air over metalloporphyrins as cytochrome P-450 monooxygenase model was reported. Upon addition of extremely low concentrations (1–5 ppm) of simple cobalt porphyrin to the commercial cyclohexane oxidation system, and decrease of the reaction temperature and pressure about 20 °C and 0.4 MPa respectively, the conversion rate of the cyclohexane oxidation increased from 4.8% to 7.1%, the yield of cyclohexanone raised from 77% to 87%, and a 70,000-ton cyclohexanone equipment set yielded an output of 125,000 tons cyclohexanone. Furthermore, a novel biological-chemical-cycle coupling mechanism was proposed to rationalize the aerobic oxidations of hydrocarbons catalyzed by the metalloporphyrins.

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Banerjee, Rahul, Jason C. Jones, and John D. Lipscomb. "Soluble Methane Monooxygenase." Annual Review of Biochemistry 88, no. 1 (June 20, 2019): 409–31. http://dx.doi.org/10.1146/annurev-biochem-013118-111529.

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Aerobic life is possible because the molecular structure of oxygen (O2) makes direct reaction with most organic materials at ambient temperatures an exceptionally slow process. Of course, these reactions are inherently very favorable, and they occur rapidly with the release of a great deal of energy at high temperature. Nature has been able to tap this sequestered reservoir of energy with great spatial and temporal selectivity at ambient temperatures through the evolution of oxidase and oxygenase enzymes. One mechanism used by these enzymes for O2activation has been studied in detail for the soluble form of the enzyme methane monooxygenase. These studies have revealed the step-by-step process of O2activation and insertion into the ultimately stable C–H bond of methane. Additionally, an elegant regulatory mechanism has been defined that enlists size selection and quantum tunneling to allow methane oxidation to occur specifically in the presence of more easily oxidized substrates.

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Vanderberg, Laura A., and Jerome J. Perry. "Dehalogenation by Mycobacterium vaccae JOB-5: role of the propane monooxygenase." Canadian Journal of Microbiology 40, no. 3 (March 1, 1994): 169–72. http://dx.doi.org/10.1139/m94-029.

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Mycobacterium vaccae JOB-5 has an inducible propane monooxygenase that has been implicated in the catabolism of most major groundwater pollutants including trichloroethylene. Propane-grown cells are also induced for the dehalogenation of 1-chlorobutane and other chloroalkanes. 1-Chlorobutane is oxidized to 2-butanol, indicating that subterminal oxidation of 1-chlorobutane resulted in a concomitant release of the chloride. Nonproliferating suspensions of M. vaccae induced for the propane monooxygenase can dehalogenate a variety of chlorinated hydrocarbons including monochlorinated alcohols, dichlorinated short chain alkanes, and several multiple-substituted compounds including trichloroethylene. The results indicate that M. vaccae JOB-5 has a monooxygenase of broad specificity that can dehalogenate an array of halogenated hydrocarbons.Key words: dehalogenation, propane monooxygenase, chlorinated alkanes.

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Cafaro, Valeria, Viviana Izzo, Roberta Scognamiglio, Eugenio Notomista, Paola Capasso, Annarita Casbarra, Piero Pucci, and Alberto Di Donato. "Phenol Hydroxylase and Toluene/o-Xylene Monooxygenase from Pseudomonas stutzeri OX1: Interplay between Two Enzymes." Applied and Environmental Microbiology 70, no. 4 (April 2004): 2211–19. http://dx.doi.org/10.1128/aem.70.4.2211-2219.2004.

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ABSTRACT Degradation of aromatic hydrocarbons by aerobic bacteria is generally divided into an upper pathway, which produces dihydroxylated aromatic intermediates by the action of monooxygenases, and a lower pathway, which processes these intermediates down to molecules that enter the citric acid cycle. Bacterial multicomponent monooxygenases (BMMs) are a family of enzymes divided into six distinct groups. Most bacterial genomes code for only one BMM, but a few cases (3 out of 31) of genomes coding for more than a single monooxygenase have been found. One such case is the genome of Pseudomonas stutzeri OX1, in which two different monooxygenases have been found, phenol hydroxylase (PH) and toluene/o-xylene monooxygenase (ToMO). We have already demonstrated that ToMO is an oligomeric protein whose subunits transfer electrons from NADH to oxygen, which is eventually incorporated into the aromatic substrate. However, no molecular data are available on the structure and on the mechanism of action of PH. To understand the metabolic significance of the association of two similar enzymatic activities in the same microorganism, we expressed and characterized this novel phenol hydroxylase. Our data indicate that the PH P component of PH transfers electrons from NADH to a subcomplex endowed with hydroxylase activity. Moreover, a regulatory function can be suggested for subunit PH M. Data on the specificity and the kinetic constants of ToMO and PH strongly support the hypothesis that coupling between the two enzymatic systems optimizes the use of nonhydroxylated aromatic molecules by the draining effect of PH on the product(s) of oxidation catalyzed by ToMO, thus avoiding phenol accumulation.

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Liew, Elissa F., Daochen Tong, Nicholas V. Coleman, and Andrew J. Holmes. "Mutagenesis of the hydrocarbon monooxygenase indicates a metal centre in subunit-C, and not subunit-B, is essential for copper-containing membrane monooxygenase activity." Microbiology 160, no. 6 (June 1, 2014): 1267–77. http://dx.doi.org/10.1099/mic.0.078584-0.

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The hydrocarbon monooxygenase (HMO) of Mycobacterium NBB4 is a member of the copper-containing membrane monooxygenase (CuMMO) superfamily, which also contains particulate methane monooxygenases (pMMOs) and ammonia monooxygenases (AMOs). CuMMOs have broad applications due to their ability to catalyse the oxidation of difficult substrates of environmental and industrial relevance. Most of our understanding of CuMMO biochemistry is based on pMMOs and AMOs as models. All three available structures are from pMMOs. These share two metal sites: a dicopper centre coordinated by histidine residues in subunit-B and a ‘variable-metal’ site coordinated by carboxylate and histidine residues from subunit-C. The exact nature and role of these sites is strongly debated. Significant barriers to progress have been the physiologically specialized nature of methanotrophs and autotrophic ammonia-oxidizers, lack of a recombinant expression system for either enzyme and difficulty in purification of active protein. In this study we use the newly developed HMO model system to perform site-directed mutagenesis on the predicted metal-binding residues in the HmoB and HmoC of NBB4 HMO. All mutations of predicted HmoC metal centre ligands abolished enzyme activity. Mutation of a predicted copper-binding residue of HmoB (B-H155V) reduced activity by 81 %. Mutation of a site that shows conservation within physiologically defined subgroups of CuMMOs was shown to reduce relative HMO activity towards larger alkanes. The study demonstrates that the modelled dicopper site of subunit-B is not sufficient for HMO activity and that a metal centre predicted to be coordinated by residues in subunit-C is essential for activity.

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Kamerbeek, Nanne M., Arjen J. J. Olsthoorn, Marco W. Fraaije, and Dick B. Janssen. "Substrate Specificity and Enantioselectivity of 4-Hydroxyacetophenone Monooxygenase." Applied and Environmental Microbiology 69, no. 1 (January 2003): 419–26. http://dx.doi.org/10.1128/aem.69.1.419-426.2003.

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ABSTRACT The 4-hydroxyacetophenone monooxygenase (HAPMO) from Pseudomonas fluorescens ACB catalyzes NADPH- and oxygen-dependent Baeyer-Villiger oxidation of 4-hydroxyacetophenone to the corresponding acetate ester. Using the purified enzyme from recombinant Escherichia coli, we found that a broad range of carbonylic compounds that are structurally more or less similar to 4-hydroxyacetophenone are also substrates for this flavin-containing monooxygenase. On the other hand, several carbonyl compounds that are substrates for other Baeyer-Villiger monooxygenases (BVMOs) are not converted by HAPMO. In addition to performing Baeyer-Villiger reactions with aromatic ketones and aldehydes, the enzyme was also able to catalyze sulfoxidation reactions by using aromatic sulfides. Furthermore, several heterocyclic and aliphatic carbonyl compounds were also readily converted by this BVMO. To probe the enantioselectivity of HAPMO, the conversion of bicyclohept-2-en-6-one and two aryl alkyl sulfides was studied. The monooxygenase preferably converted (1R,5S)-bicyclohept-2-en-6-one, with an enantiomeric ratio (E) of 20, thus enabling kinetic resolution to obtain the (1S,5R) enantiomer. Complete conversion of both enantiomers resulted in the accumulation of two regioisomeric lactones with moderate enantiomeric excess (ee) for the two lactones obtained [77% ee for (1S,5R)-2 and 34% ee for (1R,5S)-3]. Using methyl 4-tolyl sulfide and methylphenyl sulfide, we found that HAPMO is efficient and highly selective in the asymmetric formation of the corresponding (S)-sulfoxides (ee > 99%). The biocatalytic properties of HAPMO described here show the potential of this enzyme for biotechnological applications.

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Xun, Luying, and Erik R. Sandvik. "Characterization of 4-Hydroxyphenylacetate 3-Hydroxylase (HpaB) of Escherichia coli as a Reduced Flavin Adenine Dinucleotide-Utilizing Monooxygenase." Applied and Environmental Microbiology 66, no. 2 (February 1, 2000): 481–86. http://dx.doi.org/10.1128/aem.66.2.481-486.2000.

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ABSTRACT 4-Hydroxyphenylacetate 3-hydroxylase (HpaB and HpaC) ofEscherichia coli W has been reported as a two-component flavin adenine dinucleotide (FAD)-dependent monooxygenase that attacks a broad spectrum of phenolic compounds. However, the function of each component in catalysis is unclear. The large component (HpaB) was demonstrated here to be a reduced FAD (FADH2)-utilizing monooxygenase. When an E. coli flavin reductase (Fre) having no apparent homology with HpaC was used to generate FADH2 in vitro, HpaB was able to use FADH2 and O2 for the oxidation of 4-hydroxyphenylacetate. HpaB also used chemically produced FADH2 for 4-hydroxyphenylacetate oxidation, further demonstrating that HpaB is an FADH2-utilizing monooxygenase. FADH2 generated by Fre was rapidly oxidized by O2 to form H2O2 in the absence of HpaB. When HpaB was included in the reaction mixture without 4-hydroxyphenylacetate, HpaB bound FADH2 and transitorily protected it from rapid autoxidation by O2. When 4-hydroxyphenylacetate was also present, HpaB effectively competed with O2 for FADH2 utilization, leading to 4-hydroxyphenylacetate oxidation. With sufficient amounts of HpaB in the reaction mixture, FADH2 produced by Fre was mainly used by HpaB for the oxidation of 4-hydroxyphenylacetate. At low HpaB concentrations, most FADH2 was autoxidized by O2, causing uncoupling. However, the coupling of the two enzymes' activities was increased by lowering FAD concentrations in the reaction mixture. A database search revealed that HpaB had sequence similarities to several proteins and gene products involved in biosynthesis and biodegradation in both bacteria and archaea. This is the first report of an FADH2-utilizing monooxygenase that uses FADH2as a substrate rather than as a cofactor.

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de Gonzalo, Gonzalo. "Biocatalyzed Sulfoxidation in Presence of Deep Eutectic Solvents." Sustainable Chemistry 1, no. 3 (November 12, 2020): 290–97. http://dx.doi.org/10.3390/suschem1030019.

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The flavin-containing monooxygenase from Methylophaga sp. strain SK1 (mFMO) is a valuable biocatalyst for the preparation of optically active sulfoxides, among other valuable compounds. In this study, we explored to benefits of using Natural Deep Eutectic Solvents (NADESs) when doing oxidation with this biocatalyst, fused to phosphite dehydrogenase for cofactor regeneration (PTDH-mFMO). It was found that optically active sulfoxides could be obtained with slightly higher conversions in 10% v/v NADES when working at substrate concentrations of 50–200 mM, whereas there was no loss in the enantioselectivity. With these results, it is demonstrated for the first time that flavin-containing monooxygenases can be employed as biocatalysts in presence of NADESs.

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Hangasky, John A., Anthony T. Iavarone, and Michael A. Marletta. "Reactivity of O2 versus H2O2 with polysaccharide monooxygenases." Proceedings of the National Academy of Sciences 115, no. 19 (April 23, 2018): 4915–20. http://dx.doi.org/10.1073/pnas.1801153115.

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Enzymatic conversion of polysaccharides into lower-molecular-weight, soluble oligosaccharides is dependent on the action of hydrolytic and oxidative enzymes. Polysaccharide monooxygenases (PMOs) use an oxidative mechanism to break the glycosidic bond of polymeric carbohydrates, thereby disrupting the crystalline packing and creating new chain ends for hydrolases to depolymerize and degrade recalcitrant polysaccharides. PMOs contain a mononuclear Cu(II) center that is directly involved in C–H bond hydroxylation. Molecular oxygen was the accepted cosubstrate utilized by this family of enzymes until a recent report indicated reactivity was dependent on H2O2. Reported here is a detailed analysis of PMO reactivity with H2O2 and O2, in conjunction with high-resolution MS measurements. The cosubstrate utilized by the enzyme is dependent on the assay conditions. PMOs will directly reduce O2 in the coupled hydroxylation of substrate (monooxygenase activity) and will also utilize H2O2 (peroxygenase activity) produced from the uncoupled reduction of O2. Both cosubstrates require Cu reduction to Cu(I), but the reaction with H2O2 leads to nonspecific oxidation of the polysaccharide that is consistent with the generation of a hydroxyl radical-based mechanism in Fenton-like chemistry, while the O2 reaction leads to regioselective substrate oxidation using an enzyme-bound Cu/O2 reactive intermediate. Moreover, H2O2 does not influence the ability of secretome from Neurospora crassa to degrade Avicel, providing evidence that molecular oxygen is a physiologically relevant cosubstrate for PMOs.

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Di Gennaro, Patrizia, Andrea Colmegna, Enrica Galli, Guido Sello, Francesca Pelizzoni, and Giuseppina Bestetti. "A New Biocatalyst for Production of Optically Pure Aryl Epoxides by Styrene Monooxygenase from Pseudomonas fluorescensST." Applied and Environmental Microbiology 65, no. 6 (June 1, 1999): 2794–97. http://dx.doi.org/10.1128/aem.65.6.2794-2797.1999.

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ABSTRACT We developed a biocatalyst by cloning the styrene monooxygenase genes (styA and styB) from Pseudomonas fluorescens ST responsible for the oxidation of styrene to its corresponding epoxide. Recombinant Escherichia coli was able to oxidize different aryl vinyl and aryl ethenyl compounds to their corresponding optically pure epoxides. The results of bioconversions indicate the broad substrate preference of styrene monooxygenase and its potential for the production of several fine chemicals.

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Lee, S. K., M. J. Kang, C. Jin, M. K. In, D. H. Kim, and H. H. Yoo. "Flavin-containing monooxygenase 1-catalysedN,N-dimethylamphetamineN-oxidation." Xenobiotica 39, no. 9 (June 24, 2009): 680–86. http://dx.doi.org/10.1080/00498250902998699.

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Valentino, Hannah, Ashley C. Campbell, Jonathan P. Schuermann, Nazneen Sultana, Han G. Nam, Sophie LeBlanc, John J. Tanner, and Pablo Sobrado. "Structure and function of a flavin-dependent S-monooxygenase from garlic (Allium sativum)." Journal of Biological Chemistry 295, no. 32 (June 11, 2020): 11042–55. http://dx.doi.org/10.1074/jbc.ra120.014484.

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Allicin is a component of the characteristic smell and flavor of garlic (Allium sativum). A flavin-containing monooxygenase (FMO) produced by A. sativum (AsFMO) was previously proposed to oxidize S-allyl-l-cysteine (SAC) to alliin, an allicin precursor. Here, we present a kinetic and structural characterization of AsFMO that suggests a possible contradiction to this proposal. Results of steady-state kinetic analyses revealed that AsFMO exhibited negligible activity with SAC; however, the enzyme was highly active with l-cysteine, N-acetyl-l-cysteine, and allyl mercaptan. We found that allyl mercaptan with NADPH was the preferred substrate-cofactor combination. Rapid-reaction kinetic analyses showed that NADPH binds tightly (KD of ∼2 μm) to AsFMO and that the hydride transfer occurs with pro-R stereospecificity. We detected the formation of a long-wavelength band when AsFMO was reduced by NADPH, probably representing the formation of a charge-transfer complex. In the absence of substrate, the reduced enzyme, in complex with NADP+, reacted with oxygen and formed an intermediate with a spectrum characteristic of C4a-hydroperoxyflavin, which decays several orders of magnitude more slowly than the kcat. The presence of substrate enhanced C4a-hydroperoxyflavin formation and, upon hydroxylation, oxidation occurred with a rate constant similar to the kcat. The structure of AsFMO complexed with FAD at 2.08-Å resolution features two domains for binding of FAD and NADPH, representative of class B flavin monooxygenases. These biochemical and structural results are consistent with AsFMO being an S-monooxygenase involved in allicin biosynthesis through direct formation of sulfenic acid and not SAC oxidation.

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McClay, Kevin, Brian G. Fox, and Robert J. Steffan. "Toluene Monooxygenase-Catalyzed Epoxidation of Alkenes." Applied and Environmental Microbiology 66, no. 5 (May 1, 2000): 1877–82. http://dx.doi.org/10.1128/aem.66.5.1877-1882.2000.

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ABSTRACT Several toluene monooxygenase-producing organisms were tested for their ability to oxidize linear alkenes and chloroalkenes three to eight carbons long. Each of the wild-type organisms degraded all of the alkenes that were tested. Epoxides were produced during the oxidation of butene, butadiene, and pentene but not hexene or octadiene. A strain of Escherichia coli expressing the cloned toluene-4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 was able to oxidize butene, butadiene, pentene, and hexene but not octadiene, producing epoxides from all of the substrates that were oxidized. A T4MO-deficient variant of P. mendocina KR1 oxidized alkenes that were five to eight carbons long, but no epoxides were detected, suggesting the presence of multiple alkene-degrading enzymes in this organism. The alkene oxidation rates varied widely (ranging from 0.01 to 0.33 μmol of substrate/min/mg of cell protein) and were specific for each organism-substrate pair. The enantiomeric purity of the epoxide products also varied widely, ranging from 54 to >90% of a single epoxide enantiomer. In the absence of more preferred substrates, such as toluene or alkenes, the epoxides underwent further toluene monooxygenase-catalyzed transformations, forming products that were not identified.

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Cooley, Richard B., Bradley L. Dubbels, Luis A. Sayavedra-Soto, Peter J. Bottomley, and Daniel J. Arp. "Kinetic characterization of the soluble butane monooxygenase from Thauera butanivorans, formerly ‘Pseudomonas butanovora’." Microbiology 155, no. 6 (June 1, 2009): 2086–96. http://dx.doi.org/10.1099/mic.0.028175-0.

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Soluble butane monooxygenase (sBMO), a three-component di-iron monooxygenase complex expressed by the C2–C9 alkane-utilizing bacterium Thauera butanivorans, was kinetically characterized by measuring substrate specificities for C1–C5 alkanes and product inhibition profiles. sBMO has high sequence homology with soluble methane monooxygenase (sMMO) and shares a similar substrate range, including gaseous and liquid alkanes, aromatics, alkenes and halogenated xenobiotics. Results indicated that butane was the preferred substrate (defined by k cat : K m ratios). Relative rates of oxidation for C1–C5 alkanes differed minimally, implying that substrate specificity is heavily influenced by differences in substrate K m values. The low micromolar K m for linear C2–C5 alkanes and the millimolar K m for methane demonstrate that sBMO is two to three orders of magnitude more specific for physiologically relevant substrates of T. butanivorans. Methanol, the product of methane oxidation and also a substrate itself, was found to have similar K m and k cat values to those of methane. This inability to kinetically discriminate between the C1 alkane and C1 alcohol is observed as a steady-state concentration of methanol during the two-step oxidation of methane to formaldehyde by sBMO. Unlike methanol, alcohols with chain length C2–C5 do not compete effectively with their respective alkane substrates. Results from product inhibition experiments suggest that the geometry of the active site is optimized for linear molecules four to five carbons in length and is influenced by the regulatory protein component B (butane monooxygenase regulatory component; BMOB). The data suggest that alkane oxidation by sBMO is highly specialized for the turnover of C3–C5 alkanes and the release of their respective alcohol products. Additionally, sBMO is particularly efficient at preventing methane oxidation during growth on linear alkanes ≥C2, despite its high sequence homology with sMMO. These results represent, to the best of our knowledge, the first kinetic in vitro characterization of the closest known homologue of sMMO.

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Zhang, Aili, Ting Zhang, Emma A. Hall, Sean Hutchinson, Max J. Cryle, Luet-Lok Wong, Weihong Zhou, and Stephen G. Bell. "The crystal structure of the versatile cytochrome P450 enzyme CYP109B1 from Bacillus subtilis." Molecular BioSystems 11, no. 3 (2015): 869–81. http://dx.doi.org/10.1039/c4mb00665h.

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Sharma, Richa, Hilde Poelman, Guy B. Marin, and Vladimir V. Galvita. "Approaches for Selective Oxidation of Methane to Methanol." Catalysts 10, no. 2 (February 6, 2020): 194. http://dx.doi.org/10.3390/catal10020194.

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Methane activation chemistry, despite being widely reported in literature, remains to date a subject of debate. The challenges in this reaction are not limited to methane activation but extend to stabilization of the intermediate species. The low C-H dissociation energy of intermediates vs. reactants leads to CO2 formation. For selective oxidation, nature presents methane monooxygenase as a benchmark. This enzyme selectively consumes methane by breaking it down into methanol. To assemble an active site similar to monooxygenase, the literature reports Cu-ZSM-5, Fe-ZSM-5, and Cu-MOR, using zeolites and systems like CeO2/Cu2O/Cu. However, the trade-off between methane activation and methanol selectivity remains a challenge. Density functional theory (DFT) calculations and spectroscopic studies indicate catalyst reducibility, oxygen mobility, and water as co-feed as primary factors that can assist in enabling higher selectivity. The use of chemical looping can further improve selectivity. However, in all systems, improvements in productivity per cycle are required in order to meet the economical/industrial standards.

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Siewers, Verena, Jørn Smedsgaard, and Paul Tudzynski. "The P450 Monooxygenase BcABA1 Is Essential for Abscisic Acid Biosynthesis in Botrytis cinerea." Applied and Environmental Microbiology 70, no. 7 (July 2004): 3868–76. http://dx.doi.org/10.1128/aem.70.7.3868-3876.2004.

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ABSTRACT The phytopathogenic ascomycete Botrytis cinerea is known to produce abscisic acid (ABA), which is thought to be involved in host-pathogen interaction. Biochemical analyses had previously shown that, in contrast to higher plants, the fungal ABA biosynthesis probably does not proceed via carotenoids but involves direct cyclization of farnesyl diphosphate and subsequent oxidation steps. We present here evidence that this “direct” pathway is indeed the only one used by an ABA-overproducing strain of B. cinerea. Targeted inactivation of the gene bccpr1 encoding a cytochrome P450 oxidoreductase reduced the ABA production significantly, proving the involvement of P450 monooxygenases in the pathway. Expression analysis of 28 different putative P450 monooxygenase genes revealed two that were induced under ABA biosynthesis conditions. Targeted inactivation showed that one of these, bcaba1, is essential for ABA biosynthesis: ΔBcaba1 mutants contained no residual ABA. Thus, bcaba1 represents the first identified fungal ABA biosynthetic gene.

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Halsey, Kimberly H., Luis A. Sayavedra-Soto, Peter J. Bottomley, and Daniel J. Arp. "Site-Directed Amino Acid Substitutions in the Hydroxylase α Subunit of Butane Monooxygenase from Pseudomonas butanovora: Implications for Substrates Knocking at the Gate." Journal of Bacteriology 188, no. 13 (July 1, 2006): 4962–69. http://dx.doi.org/10.1128/jb.00280-06.

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ABSTRACT Butane monooxygenase (BMO) from Pseudomonas butanovora has high homology to soluble methane monooxygenase (sMMO), and both oxidize a wide range of hydrocarbons; yet previous studies have not demonstrated methane oxidation by BMO. Studies to understand the basis for this difference were initiated by making single-amino-acid substitutions in the hydroxylase α subunit of butane monooxygenase (BMOH-α) in P. butanovora. Residues likely to be within hydrophobic cavities, adjacent to the diiron center, and on the surface of BMOH-α were altered to the corresponding residues from the α subunit of sMMO. In vivo studies of five site-directed mutants were carried out to initiate mechanistic investigations of BMO. Growth rates of mutant strains G113N and L279F on butane were dramatically slower than the rate seen with the control P. butanovora wild-type strain (Rev WT). The specific activities of BMO in these strains were sevenfold lower than those of Rev WT. Strains G113N and L279F also showed 277- and 5.5-fold increases in the ratio of the rates of 2-butanol production to 1-butanol production compared to Rev WT. Propane oxidation by strain G113N was exclusively subterminal and led to accumulation of acetone, which P. butanovora could not further metabolize. Methane oxidation was measurable for all strains, although accumulation of 23 μM methanol led to complete inhibition of methane oxidation in strain Rev WT. In contrast, methane oxidation by strain G113N was not completely inhibited until the methanol concentration reached 83 μM. The structural significance of the results obtained in this study is discussed using a three-dimensional model of BMOH-α.

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Boyd, Derek R., Narain D. Sharma, Paul J. Stevenson, Patrick Hoering, Christopher C. R. Allen, and Patrick M. Dansette. "Monooxygenase- and Dioxygenase-Catalyzed Oxidative Dearomatization of Thiophenes by Sulfoxidation, cis-Dihydroxylation and Epoxidation." International Journal of Molecular Sciences 23, no. 2 (January 14, 2022): 909. http://dx.doi.org/10.3390/ijms23020909.

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Enzymatic oxidations of thiophenes, including thiophene-containing drugs, are important for biodesulfurization of crude oil and drug metabolism of mono- and poly-cyclic thiophenes. Thiophene oxidative dearomatization pathways involve reactive metabolites, whose detection is important in the pharmaceutical industry, and are catalyzed by monooxygenase (sulfoxidation, epoxidation) and dioxygenase (sulfoxidation, dihydroxylation) enzymes. Sulfoxide and epoxide metabolites of thiophene substrates are often unstable, and, while cis-dihydrodiol metabolites are more stable, significant challenges are presented by both types of metabolite. Prediction of the structure, relative and absolute configuration, and enantiopurity of chiral metabolites obtained from thiophene enzymatic oxidation depends on the substrate, type of oxygenase selected, and molecular docking results. The racemization and dimerization of sulfoxides, cis/trans epimerization of dihydrodiol metabolites, and aromatization of epoxides are all factors associated with the mono- and di-oxygenase-catalyzed metabolism of thiophenes and thiophene-containing drugs and their applications in chemoenzymatic synthesis and medicine.

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37

Yeager, Chris M., Peter J. Bottomley, and Daniel J. Arp. "Cytotoxicity Associated with Trichloroethylene Oxidation in Burkholderia cepacia G4." Applied and Environmental Microbiology 67, no. 5 (May 1, 2001): 2107–15. http://dx.doi.org/10.1128/aem.67.5.2107-2115.2001.

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ABSTRACT The effects of trichloroethylene (TCE) oxidation on toluene 2-monooxygenase activity, general respiratory activity, and cell culturability were examined in the toluene-oxidizing bacteriumBurkholderia cepacia G4. Nonspecific damage outpaced inactivation of toluene 2-monooxygenase in B. cepacia G4 cells. Cells that had degraded approximately 0.5 μmol of TCE (mg of cells−1) lost 95% of their acetate-dependent O2 uptake activity (a measure of general respiratory activity), yet toluene-dependent O2 uptake activity decreased only 35%. Cell culturability also decreased upon TCE oxidation; however, the extent of loss varied greatly (up to 3 orders of magnitude) with the method of assessment. Addition of catalase or sodium pyruvate to the surfaces of agar plates increased enumeration of TCE-injured cells by as much as 100-fold, indicating that the TCE-injured cells were ultrasensitive to oxidative stress. Cell suspensions that had oxidized TCE recovered the ability to grow in liquid minimal medium containing lactate or phenol, but recovery was delayed substantially when TCE degradation approached 0.5 μmol (mg of cells−1) or 66% of the cells' transformation capacity for TCE at the cell density utilized. Furthermore, among B. cepacia G4 cells isolated on Luria-Bertani agar plates from cultures that had degraded approximately 0.5 μmol of TCE (mg of cells−1), up to 90% were Tol− variants, no longer capable of TCE degradation. These results indicate that a toxicity threshold for TCE oxidation exists in B. cepaciaG4 and that once a cell suspension has exceeded this toxicity threshold, the likelihood of reestablishing an active, TCE-degrading biomass from the cells will decrease significantly.

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Lumb, Jean-Philip, and Kenneth Esguerra. "Cu(III)-Mediated Aerobic Oxidations." Synthesis 51, no. 02 (December 3, 2018): 334–58. http://dx.doi.org/10.1055/s-0037-1609635.

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CuIII species have been invoked in many copper-catalyzed transformations including cross-coupling reactions and oxidation reactions. In this review, we will discuss seminal discoveries that have advanced our understanding of the CuI/CuIII redox cycle in the context of C–C and C–heteroatom aerobic cross-coupling reactions, as well as C–H oxidation reactions mediated by CuIII–dioxygen adducts.1 General Introduction2 Early Examples of CuIII Complexes3 Aerobic CuIII-Mediated Carbon–Heteroatom Bond-Forming Reactions4 Aerobic CuIII-Mediated Carbon–Carbon Bond-Forming Reactions5 Bioinorganic Studies of CuIII Complexes from CuI and O2 5.1 O2 Activation5.2 Biomimetic CuIII Complexes from CuI and Dioxygen5.2.1 Type-3 Copper Enzymes and Dinuclear Cu Model Complexes5.2.2 Particulate Methane Monooxygenase and Di- and Trinuclear Cu Model Complexes5.2.3 Dopamine–β-Monooxygenase and Mononuclear Cu Model Complexes6 Conclusion

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39

Dawson, Robin A., Nasmille L. Larke-Mejía, Andrew T. Crombie, Muhammad Farhan Ul Haque, and J. Colin Murrell. "Isoprene Oxidation by the Gram-Negative Model bacterium Variovorax sp. WS11." Microorganisms 8, no. 3 (February 29, 2020): 349. http://dx.doi.org/10.3390/microorganisms8030349.

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Plant-produced isoprene (2-methyl-1,3-butadiene) represents a significant portion of global volatile organic compound production, equaled only by methane. A metabolic pathway for the degradation of isoprene was first described for the Gram-positive bacterium Rhodococcus sp. AD45, and an alternative model organism has yet to be characterised. Here, we report the characterisation of a novel Gram-negative isoprene-degrading bacterium, Variovorax sp. WS11. Isoprene metabolism in this bacterium involves a plasmid-encoded iso metabolic gene cluster which differs from that found in Rhodococcus sp. AD45 in terms of organisation and regulation. Expression of iso metabolic genes is significantly upregulated by both isoprene and epoxyisoprene. The enzyme responsible for the initial oxidation of isoprene, isoprene monooxygenase, oxidises a wide range of alkene substrates in a manner which is strongly influenced by the presence of alkyl side-chains and differs from other well-characterised soluble diiron monooxygenases according to its response to alkyne inhibitors. This study presents Variovorax sp. WS11 as both a comparative and contrasting model organism for the study of isoprene metabolism in bacteria, aiding our understanding of the conservation of this biochemical pathway across diverse ecological niches.

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Zhou, Qiang, Shu-Ya Peng, Kai Zhang, Guang-Cai Luo, Li Han, Qing-Li He, and Gong-Li Tang. "A Flavin-Dependent Monooxygenase Mediates Divergent Oxidation of Rifamycin." Organic Letters 23, no. 6 (March 8, 2021): 2342–46. http://dx.doi.org/10.1021/acs.orglett.1c00485.

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41

Ottolina, Gianluca, Silvia Bianchi, Barbara Belloni, Giacoma Carrea, and Bruno Danieli. "First asymmetric oxidation of tertiary amines by cyclohexanone monooxygenase." Tetrahedron Letters 40, no. 48 (November 1999): 8483–86. http://dx.doi.org/10.1016/s0040-4039(99)01780-3.

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42

Beneventi, Elisa, Gianluca Ottolina, Giacomo Carrea, Walter Panzeri, Giovanni Fronza, and Peter C. K. Lau. "Enzymatic Baeyer–Villiger oxidation of steroids with cyclopentadecanone monooxygenase." Journal of Molecular Catalysis B: Enzymatic 58, no. 1-4 (June 2009): 164–68. http://dx.doi.org/10.1016/j.molcatb.2008.12.009.

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43

Beneventi, E., G. Ottolina, G. Carrea, W. Panzeri, G. Fronza, and P. C. K. Lau. "Enzymatic Baeyer-Villiger oxidation of steroids with cyclopentadecanone monooxygenase." Journal of Biotechnology 150 (November 2010): 356. http://dx.doi.org/10.1016/j.jbiotec.2010.09.407.

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44

Colonna, Stefano, Nicoletta Gaggero, Anna Bertinotti, Giacomo Carrea, Piero Pasta, and Antonella Bernardi. "Enantioselective oxidation of 1,3-dithioacetals catalysed by cyclohexanone monooxygenase." Journal of the Chemical Society, Chemical Communications, no. 11 (1995): 1123. http://dx.doi.org/10.1039/c39950001123.

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45

Bell, Stephen G., Rebecca J. Sowden, and Luet-Lok Wong. "Engineering the haem monooxygenase cytochrome P450cam for monoterpene oxidation." Chemical Communications, no. 7 (2001): 635–36. http://dx.doi.org/10.1039/b100290m.

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46

SECUNDO, F., G. CARREA, S. DALLAVALLE, and G. FRANZOSI. "ChemInform Abstract: Asymmetric Oxidation of Sulfides by Cyclohexanone Monooxygenase." ChemInform 25, no. 2 (August 19, 2010): no. http://dx.doi.org/10.1002/chin.199402057.

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47

Rehdorf, Jessica, Christian L. Zimmer, and Uwe T. Bornscheuer. "Cloning, Expression, Characterization, and Biocatalytic Investigation of the 4-Hydroxyacetophenone Monooxygenase from Pseudomonas putida JD1." Applied and Environmental Microbiology 75, no. 10 (February 27, 2009): 3106–14. http://dx.doi.org/10.1128/aem.02707-08.

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ABSTRACT While the number of available recombinant Baeyer-Villiger monooxygenases (BVMOs) has grown significantly over the last few years, there is still the demand for other BVMOs to expand the biocatalytic diversity. Most BVMOs that have been described are dedicated to convert efficiently cyclohexanone and related cyclic aliphatic ketones. To cover a broader range of substrate types and enantio- and/or regioselectivities, new BVMOs have to be discovered. The gene encoding a BVMO identified in Pseudomonas putida JD1 converting aromatic ketones (HAPMO; 4-hydroxyacetophenone monooxygenase) was amplified from genomic DNA using SiteFinding-PCR, cloned, and functionally expressed in Escherichia coli. Furthermore, four other open reading frames could be identified clustered around this HAPMO. It has been suggested that these proteins, including the HAPMO, might be involved in the degradation of 4-hydroxyacetophenone. Substrate specificity studies revealed that a large variety of other arylaliphatic ketones are also converted via Baeyer-Villiger oxidation into the corresponding esters, with preferences for para-substitutions at the aromatic ring. In addition, oxidation of aldehydes and some heteroaromatic compounds was observed. Cycloketones and open-chain ketones were not or poorly accepted, respectively. It was also found that this enzyme oxidizes aromatic ketones such as 3-phenyl-2-butanone with excellent enantioselectivity (E ≫100).

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Vardar, Gönül, and Thomas K. Wood. "Alpha-Subunit Positions Methionine 180 and Glutamate 214 of Pseudomonas stutzeri OX1 Toluene-o-Xylene Monooxygenase Influence Catalysis." Journal of Bacteriology 187, no. 4 (February 15, 2005): 1511–14. http://dx.doi.org/10.1128/jb.187.4.1511-1514.2005.

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ABSTRACT Alpha-subunit position M180 of toluene-o-xylene monooxygenase influences the regiospecific oxidation of aromatics (e.g., from o-cresol, M180H forms 3-methylcatechol, methylhydroquinone, and 4-methylresorcinol, whereas the wild type forms only 3-methylcatechol). Position E214 influences the rate of reaction (e.g., E214G increases p-nitrophenol oxidation 15-fold) by controlling substrate entrance and product efflux as a gate residue.

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Hashimoto, Takafumi, Daiki Nozawa, Katsuyuki Mukai, Akinobu Matsuyama, Kouji Kuramochi, and Toshiki Furuya. "Monooxygenase-catalyzed regioselective hydroxylation for the synthesis of hydroxyequols." RSC Advances 9, no. 38 (2019): 21826–30. http://dx.doi.org/10.1039/c9ra03913a.

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50

Hristova, Krassimira R., Radomir Schmidt, Anu Y. Chakicherla, Tina C. Legler, Janice Wu, Patrick S. Chain, Kate M. Scow, and Staci R. Kane. "Comparative Transcriptome Analysis of Methylibium petroleiphilum PM1 Exposed to the Fuel Oxygenates Methyl tert-Butyl Ether and Ethanol." Applied and Environmental Microbiology 73, no. 22 (September 21, 2007): 7347–57. http://dx.doi.org/10.1128/aem.01604-07.

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Abstract:

ABSTRACT High-density whole-genome cDNA microarrays were used to investigate substrate-dependent gene expression of Methylibium petroleiphilum PM1, one of the best-characterized aerobic methyl tert-butyl ether (MTBE)-degrading bacteria. Differential gene expression profiling was conducted with PM1 grown on MTBE and ethanol as sole carbon sources. Based on microarray high scores and protein similarity analysis, an MTBE regulon located on the megaplasmid was identified for further investigation. Putative functions for enzymes encoded in this regulon are described with relevance to the predicted MTBE degradation pathway. A new unique dioxygenase enzyme system that carries out the hydroxylation of tert-butyl alcohol to 2-methyl-2-hydroxy-1-propanol in M. petroleiphilum PM1 was discovered. Hypotheses regarding the acquisition and evolution of MTBE genes as well as the involvement of IS elements in these complex processes were formulated. The pathways for toluene, phenol, and alkane oxidation via toluene monooxygenase, phenol hydroxylase, and propane monooxygenase, respectively, were upregulated in MTBE-grown cells compared to ethanol-grown cells. Four out of nine putative cyclohexanone monooxygenases were also upregulated in MTBE-grown cells. The expression data allowed prediction of several hitherto-unknown enzymes of the upper MTBE degradation pathway in M. petroleiphilum PM1 and aided our understanding of the regulation of metabolic processes that may occur in response to pollutant mixtures and perturbations in the environment.

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Journal articles on the topic 'Monooxygenase oxidation'

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