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Ningyu Huang, Xiaojuan Pei, Wenbo Lin, Jen-Fu Chiu, Tao Tao, Guanwu Li
NAD(P)H:quinone oxidoreductase 1 (NQO1), a phase II flavoenzyme that catalyzes reduction reactions to protect cells against electrophiles and oxidants, is involved in tumorigenesis. Altered methylation of the NQO1 gene has been observed and is speculated to result in aberrant NQO1 expression in rat cells undergoing chemical carcinogenesis, although this has not been proven experimentally. In this study, we first investigated the potential epigenetic mechanisms underlying the phenomenon of NQO1 differential expression in individual subclones of rat arsenic-transformed lung epithelial cells (TLECs)...
June 8, 2018: Acta Biochimica et Biophysica Sinica
Do Wan Kim, Ki Seog Lee, Young Min Chi
Nitroalkane oxidase (NAO) and nitronate monooxygenase (NMO) are two different types of nitroalkane oxidizing flavoenzymes identified in nature. A previous study suggested that the hypothetical protein PA4202 from Pseudomonas aeruginosa PAO1 is NMO and utilizes only anionic nitronates. However, the structural similarity between the PA4202 protein and Streptomyces ansochromogenes NAO has motivated investigation for what features of the two enzymes differentiate between the NAO and NMO activities. Herein, we report the crystal structure of PA4202 in a ternary complex with a neutral nitroethane (NE) and flavin mononucleotide (FMN) cofactor to elucidate the substrate recognition mechanism using a site-directed mutagenesis...
June 7, 2018: Biochemical and Biophysical Research Communications
Halis Türker Balaydın, Musa Özil, Murat Şentürk
Glutathione reductase (GR) is responsible for the existence of the reduced glutathione (GSH) molecule, a crucial antioxidant against oxidative stress reagents. The antimalarial activities of some redox active compounds are attributed to their inhibition of antioxidant flavoenzyme GR, and inhibitors are therefore expected to be useful for the treatment of malaria. In this work, a fast and effective synthesis and the GR inhibitory properties of 5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one's aryl Schiff base derivatives are reported...
June 8, 2018: Archiv der Pharmazie
Jumpei Sasabe, Masataka Suzuki
Mammalian innate and adaptive immune systems use the pattern recognition receptors, such as toll-like receptors, to detect conserved bacterial and viral components. Bacteria synthesize diverse D-amino acids while eukaryotes and archaea generally produce two D-amino acids, raising the possibility that many of bacterial D-amino acids are bacteria-specific metabolites. Although D-amino acids have not been identified to bind to any known pattern recognition receptors, D-amino acids are enantioselectively recognized by some other receptors and enzymes including a flavoenzyme D-amino acid oxidase (DAO) in mammals...
2018: Frontiers in Microbiology
Margarita A Tararina, Song Xue, Lauren C Smith, Samantha N Muellers, Pedro O Miranda, Kim D Janda, Karen N Allen
Nicotine oxidoreductase (NicA2) is a bacterial flavoenzyme, which catalyzes the first step of nicotine catabolism by oxidizing S-nicotine into N-methyl-myosmine. Its use has been proposed as a biotherapeutic for nicotine addiction due to its nanomolar substrate binding affinity. The first crystal structure of NicA2 has been reported, establishing NicA2 as a member of the monoamine oxidase (MAO) family. However, substrate specificity and structural determinants of substrate binding/catalysis have not been explored...
May 29, 2018: Biochemistry
Celso Almeida, Ignacio Pérez-Victoria, Víctor González-Menéndez, Nuria de Pedro, Jesús Martín, Gloria Crespo, Thomas Mackenzie, Bastien Cautain, Fernando Reyes, Francisca Vicente, Olga Genilloud
Two new epimeric dihalogenated diaporthins, (9 R * )-8-methyl-9,11-dichlorodiaporthin (2) and (9 S * )-8-methyl-9,11-dichlorodiaporthin (3), have been isolated from the soil fungus Hamigera fusca NRRL 35721 alongside the known regioisomeric isocoumarin 8-methyl-11,11-dichlorodiaporthin (1). Their structures were elucidated by high-resolution mass spectrometry and NMR spectroscopy combined with molecular modeling. Compounds 1-3 are the first isocoumarins and the first halogenated metabolites ever reported from the Hamigera genus...
May 24, 2018: Journal of Natural Products
Robin Teufel
Flavoenzymes often function as oxygenases and have been extensively studied for many decades. Commonly, oxygenation reactions are mediated by a transient C4a-peroxyflavin formed from reaction of reduced flavin with O2 . EncM, however, employs a previously unrecognized flavin-oxygenating species, the flavin-N5-oxide, which is key to a complex oxidative Favorskii-type rearrangement and cyclization cascade in the biosynthesis of the bacterial polyketide antibiotic enterocin produced by the marine bacterium Streptomyces maritimus...
2018: Methods in Enzymology
Yo Okamura, Mari Inada, Gehad Elsaid Elshopakey, Toshiaki Itami
Reactive oxygen species (ROS) play key roles in many physiological processes. In particular, the sterilization mechanism of bacteria using ROS in macrophages is a very important function for biological defense. Xanthine dehydrogenase (XDH) and aldehyde oxidase (AOX), members of the molybdo-flavoenzyme subfamily, are known to generate ROS. Although these enzymes occur in many vertebrates, some insects, and plants, little research has been conducted on XDHs and AOXs in crustaceans. Here, we cloned the entire cDNA sequences of XDH (MjXDH: 4328 bp) and AOX (MjAOX: 4425 bp) from Marsupenaeus japonicus (kuruma shrimp) using reverse transcriptase-polymerase chain reaction (RT-PCR) and random amplification of cDNA ends (RACE)...
May 16, 2018: Molecular Biology Reports
Yuma Terai, Ryuma Sato, Takahiro Yumiba, Ryuhei Harada, Kohei Shimizu, Tatsuya Toga, Tomoko Ishikawa-Fujiwara, Takeshi Todo, Shigenori Iwai, Yasuteru Shigeta, Junpei Yamamoto
(6-4) Photolyases ((6-4)PLs) are flavoenzymes that repair the carcinogenic UV-induced DNA damage, pyrimidine(6-4)pyrimidone photoproducts ((6-4)PPs), in a light-dependent manner. Although the reaction mechanism of DNA photorepair by (6-4)PLs has been intensively investigated, the molecular mechanism of the lesion recognition remains obscure. We show that a well-conserved arginine residue in Xenopus laevis (6-4)PL (Xl64) participates in DNA binding, through Coulomb and CH-π interactions. Fragment molecular orbital calculations estimated attractive interaction energies of -80-100 kcal mol-1 for the Coulomb interaction and -6 kcal mol-1 for the CH-π interaction, and the loss of either of them significantly reduced the affinity for (6-4)PP-containing oligonucleotides, as well as the quantum yield of DNA photorepair...
May 14, 2018: Nucleic Acids Research
Gustavo Pierdominici-Sottile, Rodrigo Cossio-P Eacute Rez, Isabel Da Fonseca, Karina Kizjakina, John J Tanner, Pablo Sobrado
Galactose is an abundant monosaccharide found exclusively in mammals as galactopyranose (Galp), the six-membered ring form of this sugar. In contrast, galactose appears in many pathogenic microorganisms as the five-membered ring form, galactofuranose (Galf). Galf biosynthesis begins with the conversion of UDP-Galp to UDP-Galf catalyzed by the flavoenzyme UDP-galactopyranose mutase (UGM). Because UGM is essential for the survival and proliferation of several pathogens, there is interest in understanding the catalytic mechanism to aid inhibitor development...
May 14, 2018: Biochemistry
Pamela Cappelletti, Elena Tallarita, Valentina Rabattoni, Paola Campomenosi, Silvia Sacchi, Loredano Pollegioni
L-Proline is a multifunctional amino acid that plays an essential role in primary metabolism and physiological functions. Proline is oxidized to glutamate in the mitochondria and the FAD-containing enzyme proline oxidase (PO) catalyzes the first step in L-proline degradation pathway. Alterations in proline metabolism have been described in various human diseases, such as hyperprolinemia type I, velo-cardio-facial syndrome/Di George syndrome, schizophrenia and cancer. In particular, the mutation giving rise to the substitution Leu441Pro was identified in patients suffering of schizophrenia and hyperprolinemia type I...
2018: PloS One
Raspudin Saleem-Batcha, Frederick Stull, Jacob N Sanders, Bradley S Moore, Bruce A Palfey, K N Houk, Robin Teufel
The reactions of enzymes and cofactors with gaseous molecules such as dioxygen (O2 ) are challenging to study and remain among the most contentious subjects in biochemistry. To date, it is largely enigmatic how enzymes control and fine-tune their reactions with O2 , as exemplified by the ubiquitous flavin-dependent enzymes that commonly facilitate redox chemistry such as the oxygenation of organic substrates. Here we employ O2 -pressurized X-ray crystallography and quantum mechanical calculations to reveal how the precise positioning of O2 within a flavoenzyme's active site enables the regiospecific formation of a covalent flavin-oxygen adduct and oxygenating species (i...
May 8, 2018: Proceedings of the National Academy of Sciences of the United States of America
Pavel Müller, Elisabeth Ignatz, Stephan Kiontke, Klaus Brettel, Lars-Oliver Essen
Class II DNA photolyases are flavoenzymes occurring in both prokaryotes and eukaryotes including higher plants and animals. Despite considerable structural deviations from the well-studied class I DNA photolyases, they share the main biological function, namely light-driven repair of the most common UV-induced lesions in DNA, the cyclobutane pyrimidine dimers (CPDs). For DNA repair activity, photolyases require the fully reduced flavin adenine dinucleotide cofactor, FADH- , which can be obtained from oxidized or semi-reduced FAD by a process called photoactivation...
February 7, 2018: Chemical Science
Gudrun Gygli, Ronald P de Vries, Willem J H van Berkel
Vanillyl alcohol oxidase (VAO) is a fungal flavoenzyme that converts a wide range of para-substituted phenols. The products of these conversions, e.g. vanillin, coniferyl alcohol and chiral aryl alcohols, are of interest for several industries. VAO is the only known fungal member of the 4-phenol oxidising (4PO) subgroup of the VAO/PCMH flavoprotein family. While the enzyme has been biochemically characterised in great detail, little is known about its physiological role and distribution in fungi. We have identified and analysed novel, fungal candidate VAOs and found them to be mostly present in Pezizomycotina and Agaricomycotina...
April 5, 2018: Fungal Genetics and Biology: FG & B
Parismita Kalita, Harish Shukla, Rohit Shukla, Timir Tripathi
The thiol-disulfide redox metabolism in platyhelminth parasites depends entirely on a single selenocysteine (Sec) containing flavoenzyme, thioredoxin glutathione reductase (TGR) that links the classical thioredoxin (Trx) and glutathione (GSH) systems. In the present study, we investigated the catalytic and structural properties of different variants of Fasciola gigantica TGR to understand the role of Sec. The recombinant full-length Sec containing TGR (FgTGRsec), TGR without Sec (FgTGR) and TGRsec without the N-terminal glutaredoxin (Grx) domain (∆NTD-FgTGRsec) were purified to homogeneity...
March 9, 2018: Biochimica et Biophysica Acta
Tapaswini Nayak, Lingaraja Jena, Pranita Waghmare, Bhaskar C Harinath
Background: The Mycobacterium tuberculosis (MTB) uridine diphosphogalactofuranose (UDP)-galactopyranose mutase (UGM) is an essential flavoenzyme for mycobacterial viability and an important component of cell wall. It catalyzes the interconversion of UDP-galactopyranose into UDP-galactofuranose, a key building block for cell wall construction, essential for linking the peptidoglycan and mycolic acid cell wall layers in MTB through a 2-keto intermediate. Further, as this enzyme is not present in humans, it is an excellent therapeutic target for MTB...
January 2018: International Journal of Mycobacteriology
Victor L Davidson
A protein-derived cofactor is a catalytic or redox-active site in a protein that is formed by post-translational modification of one or more amino acid residues. These post-translational modifications are irreversible and endow the modified amino acid residues with new functional properties. This Perspective focuses on the following advances in this area that have occurred during recent years. The biosynthesis of the tryptophan tryptophylquinone cofactor is catalyzed by a diheme enzyme, MauG. A bis-FeIV redox state of the hemes performs three two-electron oxidations of specific Trp residues via long-range electron transfer...
March 6, 2018: Biochemistry
Farida Larit, Khaled M Elokely, Narayan D Chaurasiya, Samira Benyahia, Manal A Nael, Francisco León, Mohammad Sanad Abu-Darwish, Thomas Efferth, Yan-Hong Wang, Djamila Belouahem-Abed, Samir Benayache, Babu L Tekwani, Stephen J Cutler
BACKGROUND: Monoamine oxidases (MAOs) are outer mitochondrial membrane flavoenzymes. They catalyze the oxidative deamination of a variety of neurotransmitters. MAO-A and MAO-B may be considered as targets for inhibitors to treat neurodegenerative diseases and depression and for managing symptoms associated with Parkinson's and Alzheimer's diseases. PURPOSE: The objective was to evaluate the inhibitory effect of Hypericum afrum and Cytisus villosus against MAO-A and B and to isolate the compounds responsible for the MAO-inhibitory activity...
February 1, 2018: Phytomedicine: International Journal of Phytotherapy and Phytopharmacology
Juan Carro, Patricia Ferreira, Angel T Martínez, Giovanni Gadda
The mechanism of dioxygen reduction by the flavoenzyme aryl-alcohol oxidase was investigated with kinetic isotope, viscosity, and pL (pH/pD) effects in rapid kinetics experiments by stopped-flow spectrophotometry of the oxidative half-reaction of the enzyme. Double mixing of the enzyme in a stopped-flow spectrophotometer with [α-2 H2 ]- p-methoxybenzyl alcohol and oxygen at varying aging times established a slow rate constant of 0.0023 s-1 for the wash-out of the D atom from the N5 atom of the reduced flavin...
March 20, 2018: Biochemistry
Dale E Edmondson, Claudia Binda
Monoamine oxidases A and B (MAO A and B) are mammalian flavoenzymes bound to the outer mitochondrial membrane. They were discovered almost a century ago and they have been the subject of many biochemical, structural and pharmacological investigations due to their central role in neurotransmitter metabolism. Currently, the treatment of Parkinson's disease involves the use of selective MAO B inhibitors such as rasagiline and safinamide. MAO inhibition was shown to exert a general neuroprotective effect as a result of the reduction of oxidative stress produced by these enzymes, which seems to be relevant also in non-neuronal contexts...
2018: Sub-cellular Biochemistry
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