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Flavoenzyme

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https://www.readbyqxmd.com/read/28098177/an-extended-n-h-bond-driven-by-a-conserved-second-order-interaction-orients-the-flavin-n5-orbital-in-cholesterol-oxidase
#1
Emily Golden, Li-Juan Yu, Flora Meilleur, Matthew P Blakeley, Anthony P Duff, Amir Karton, Alice Vrielink
The protein microenvironment surrounding the flavin cofactor in flavoenzymes is key to the efficiency and diversity of reactions catalysed by this class of enzymes. X-ray diffraction structures of oxidoreductase flavoenzymes have revealed recurrent features which facilitate catalysis, such as a hydrogen bond between a main chain nitrogen atom and the flavin redox center (N5). A neutron diffraction study of cholesterol oxidase has revealed an unusual elongated main chain nitrogen to hydrogen bond distance positioning the hydrogen atom towards the flavin N5 reactive center...
January 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28080034/the-mechanism-of-the-flavoprotein-6-hydroxy-l-nicotine-oxidase-ph-and-solvent-isotope-effects-and-identification-of-key-active-site-residues
#2
Paul F Fitzpatrick, Fatemeh Chadegani, Shengnan Zhang, Vi Dougherty
The flavoenzyme L-6-hydroxynicotine oxidase (LHNO) is a member of the monoamine oxidase family that catalyzes the oxidation of (S)-6-hydroxynicotine to 6-hydroxypseudooxynicotine during microbial catabolism of nicotine. While the enzyme has long been understood to catalyze oxidation of carbon-carbon bond, it has recently been shown to catalyze oxidation of a carbon-nitrogen bond (Fitzpatrick et al., Biochemistry 55, 697-703). The effects of pH and mutagenesis of active site residues have now been utilized to study the mechanism and the roles of active site residues...
January 12, 2017: Biochemistry
https://www.readbyqxmd.com/read/28070495/an-atypical-presentation-of-acad9-deficiency-diagnosis-by-whole-exome-sequencing-broadens-the-phenotypic-spectrum-and-alters-treatment-approach
#3
H K Aintablian, V Narayanan, N Belnap, K Ramsey, T A Grebe
Acyl-CoA dehydrogenase 9 (ACAD9), linked to chromosome 3q21.3, is one of a family of multimeric mitochondrial flavoenzymes that catalyze the degradation of fatty acyl-CoA from the carnitine shuttle via β-oxidation (He et al. 2007). ACAD9, specifically, is implicated in the processing of palmitoyl-CoA and long-chain unsaturated substrates, but unlike other acyl-CoA dehydrogenases (ACADs), it has a significant role in mitochondrial complex I assembly (Nouws et al. 2010 & 2014). Mutations in this enzyme typically cause mitochondrial complex I deficiency, as well as a mild defect in long chain fatty acid metabolism (Haack et al...
March 2017: Molecular Genetics and Metabolism Reports
https://www.readbyqxmd.com/read/28055208/thiol-based-probe-for-electrophilic-natural-products-reveals-that-most-of-the-ammosamides-are-artifacts
#4
Daniela Reimer, Chambers C Hughes
To date, 16 members of the ammosamide family of natural products have been discovered, and except for ammosamide D each of these metabolites is characterized by an unusual chlorinated pyrrolo[4,3,2-de]quinoline skeleton. Several ammosamides have been shown to inhibit quinone reductase 2, a flavoenzyme responsible for quelling toxic oxidative species in cells or for killing cancer cells outright. Treatment of the extract from an ammosamide-producing culture (Streptomyces strain CNR-698) with a thiol-based reagent designed to label electrophilic natural products produced an ammosamide C-thiol adduct...
January 5, 2017: Journal of Natural Products
https://www.readbyqxmd.com/read/28032983/two-flavoenzymes-catalyze-the-post-translational-generation-of-5-chlorotryptophan-and-2-aminovinyl-cysteine-during-nai-107-biosynthesis
#5
Manuel A Ortega, Dillon P Cogan, Subha Mukherjee, Neha Garg, Bo Li, Gabrielle N Thibodeaux, Sonia I Maffioli, Stefano Donadio, Margherita Sosio, Jerome Escano, Leif Smith, Satish K Nair, Wilfred A van der Donk
Lantibiotics are ribosomally synthesized and post-translationally modified antimicrobial peptides containing thioether rings. In addition to these cross-links, the clinical candidate lantibiotic NAI-107 also possesses a C-terminal S-[(Z)-2-aminovinyl]-d-cysteine (AviCys) and a unique 5-chloro-l-tryptophan (ClTrp) moiety linked to its potent bioactivity. Bioinformatic and genetic analyses on the NAI-107 biosynthetic gene cluster identified mibH and mibD as genes encoding flavoenzymes responsible for the formation of ClTrp and AviCys, respectively...
January 13, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28032259/role-of-the-nad-p-h-quinone-oxidoreductase-nqr-and-the-cytochrome-b-air12-in-controlling-superoxide-generation-at-the-plasma-membrane
#6
Catherine Biniek, Eiri Heyno, Jerzy Kruk, Francesca Sparla, Paolo Trost, Anja Krieger-Liszkay
The quinone reductase NQR and the b-type cytochrome AIR12 of the plasma membrane are important for the control of reactive oxygen species in the apoplast. AIR12 and NQR are two proteins attached to the plant plasma membrane which may be important for generating and controlling levels of reactive oxygen species in the apoplast. AIR12 (Auxin Induced in Root culture) is a single gene of Arabidopsis that codes for a mono-heme cytochrome b. The NADPH quinone oxidoreductase NQR is a two-electron-transferring flavoenzyme that contributes to the generation of O 2(•-) in isolated plasma membranes...
December 28, 2016: Planta
https://www.readbyqxmd.com/read/27995996/the-quantum-biology-of-reactive-oxygen-species-partitioning-impacts-cellular-bioenergetics
#7
Robert J Usselman, Cristina Chavarriaga, Pablo R Castello, Maria Procopio, Thorsten Ritz, Edward A Dratz, David J Singel, Carlos F Martino
Quantum biology is the study of quantum effects on biochemical mechanisms and biological function. We show that the biological production of reactive oxygen species (ROS) in live cells can be influenced by coherent electron spin dynamics, providing a new example of quantum biology in cellular regulation. ROS partitioning appears to be mediated during the activation of molecular oxygen (O2) by reduced flavoenzymes, forming spin-correlated radical pairs (RPs). We find that oscillating magnetic fields at Zeeman resonance alter relative yields of cellular superoxide (O2(•-)) and hydrogen peroxide (H2O2) ROS products, indicating coherent singlet-triplet mixing at the point of ROS formation...
December 20, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27992654/repair-of-6-4-lesions-in-dna-by-6-4-photolyase-20-years-of-quest-for-the-photoreaction-mechanism
#8
Junpei Yamamoto, Pascal Plaza, Klaus Brettel
Exposure of DNA to ultraviolet (UV) light from the Sun or from other sources causes formation of harmful and carcinogenic crosslinks between adjacent pyrimidine nucleobases, namely cyclobutane pyrimidine dimers and pyrimidine(6-4)pyrimidone photoproducts. Nature has developed unique flavoenzymes, called DNA photolyases, that utilize blue light, i.e. photons of lower energy than those of the damaging light, to repair these lesions. In this review, we focus on the chemically challenging repair of the (6-4) photoproducts by (6-4) photolyase and describe the major events along the quest for the reaction mechanisms, over the 20 years since the discovery of (6-4) photolyase...
December 19, 2016: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/27922192/evidence-for-pipecolate-oxidase-in-mediating-protection-against-hydrogen-peroxide-stress
#9
Sathish Kumar Natarajan, Ezhumalai Muthukrishnan, Oleh Khalimonchuk, Justin L Mott, Donald F Becker
Pipecolate, an intermediate of the lysine catabolic pathway, is oxidized to Δ(1) -piperideine-6-carboxylate (P6C) by the flavoenzyme l-pipecolate oxidase (PIPOX). P6C spontaneously hydrolyzes to generate α-aminoadipate semialdehyde, which is then converted into α-aminoadipate acid by α-aminoadipatesemialdehyde dehydrogenase. l-pipecolate was previously reported to protect mammalian cells against oxidative stress. Here, we examined whether PIPOX is involved in the mechanism of pipecolate stress protection...
December 6, 2016: Journal of Cellular Biochemistry
https://www.readbyqxmd.com/read/27825927/flavin-dependent-methylation-of-rnas-complex-chemistry-for-a-simple-modification
#10
REVIEW
Djemel Hamdane, Henri Grosjean, Marc Fontecave
RNA methylation is the most abundant and evolutionarily conserved chemical modification of bases or ribose in noncoding and coding RNAs. This rather simple modification has nevertheless major consequences on the function of maturated RNA molecules and ultimately on their cellular fates. The methyl group employed in the methylation is almost universally derived from S-adenosyl-L-methionine via a simple SN2 displacement reaction. However, in some rare cases, the carbon originates from N5,N10-methylenetetrahydrofolate (CH2=THF)...
December 4, 2016: Journal of Molecular Biology
https://www.readbyqxmd.com/read/27816454/identification-of-an-extracellular-bacterial-flavoenzyme-that-can-prevent-re-polymerisation-of-lignin-fragments
#11
Rahman Rahmanpour, Lloyd D W King, Timothy D H Bugg
A significant problem in the oxidative breakdown of lignin is the tendency of phenolic radical fragments to re-polymerise to form higher molecular weight species. In this paper we identify an extracellular flavin-dependent dehydrolipoamide dehydrogenase from Thermobifida fusca that prevents oxidative dimerization of a dimeric lignin model compound, which could be used as an accessory enzyme for lignin depolymerisation.
January 1, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/27777067/securinine-disturbs-redox-homeostasis-and-elicits-oxidative-stress-mediated-apoptosis-via-targeting-thioredoxin-reductase
#12
Junmin Zhang, Juan Yao, Shoujiao Peng, Xinming Li, Jianguo Fang
Thioredoxin reductase (TrxR) and thioredoxin (Trx) are two major components of the thioredoxin system, which plays essential roles in regulating cellular redox signaling. Mammalian TrxRs are essential seleno-flavoenzymes with a conserved penultimate selenocysteine (Sec) residue at the C-terminus, and have attracted considerable interests as promising targets for anticancer drugs. Securinine (SCR), a major active alkaloid lactone from the Chinese herbal medicine Securinega suffruticosa, has been established clinical success in treatment of neurological disorders...
January 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/27742866/engineering-a-trifunctional-proline-utilization-a-chimera-by-fusing-a-dna-binding-domain-to-a-bifunctional-puta
#13
Benjamin W Arentson, Erin L Hayes, Weidong Zhu, Harkewal Singh, John J Tanner, Donald F Becker
Proline utilization A (PutA) is a bifunctional flavoenzyme with proline dehydrogenase (PRODH) and Δ(1)-pyrroline-5-carboxylate dehydrogenase domains that catalyzes the two-step oxidation of proline to glutamate. Trifunctional PutAs also have an N-terminal ribbon-helix-helix (RHH) DNA-binding domain and moonlight as autogenous transcriptional repressors of the put regulon. A unique property of trifunctional PutA is the ability to switch functions from DNA-bound repressor to membrane-associated enzyme in response to cellular nutritional needs and proline availability...
October 14, 2016: Bioscience Reports
https://www.readbyqxmd.com/read/27734680/empirical-valence-bond-simulations-of-the-hydride-transfer-step-in-the-monoamine-oxidase-a-catalyzed-metabolism-of-noradrenaline
#14
Matic Poberžnik, Miha Purg, Matej Repič, Janez Mavri, Robert Vianello
Monoamine oxidases (MAOs) A and B are flavoenzymes responsible for the metabolism of biogenic amines, such as dopamine, serotonin, and noradrenaline (NA), which is why they have been extensively implicated in the etiology and course of various neurodegenerative disorders and, accordingly, used as primary pharmacological targets to treat these debilitating cognitive diseases. The precise chemical mechanism through which MAOs regulate the amine concentration, which is vital for the development of novel inhibitors, is still not unambiguously determined in the literature...
November 10, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27676389/untangling-heavy-protein-and-cofactor-isotope-effects-on-enzyme-catalyzed-hydride-transfer
#15
James E Longbotham, Samantha J O Hardman, Stefan Görlich, Nigel S Scrutton, Sam Hay
"Heavy" (isotopically labeled) enzyme isotope effects offer a direct experimental probe of the role of protein vibrations on enzyme-catalyzed reactions. Here we have developed a strategy to generate isotopologues of the flavoenzyme pentaerythritol tetranitrate reductase (PETNR) where the protein and/or intrinsic flavin mononucleotide (FMN) cofactor are isotopically labeled with (2)H, (15)N, and (13)C. Both the protein and cofactor contribute to the enzyme isotope effect on the reductive hydride transfer reaction, but their contributions are not additive and may partially cancel each other out...
October 7, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27666194/structural-studies-of-mycobacterium-tuberculosis-dpre1-interacting-with-its-inhibitors
#16
Jérémie Piton, Caroline S-Y Foo, Stewart T Cole
The flavoenzyme DprE1 catalyses a crucial step in arabinan production for cell wall biosynthesis in Mycobacterium tuberculosis and is a highly vulnerable drug target. It was first discovered using benzothiazinones (BTZ): exquisitely potent bactericidal agents that are being developed as drugs to treat tuberculosis. Subsequently, many compounds with diverse scaffolds were found to act as either covalent or noncovalent DprE1 inhibitors. Covalent inhibitors, like the BTZ, are all nitroaromatic compounds that serve as suicide substrates after DprE1-mediated nitroreduction...
September 22, 2016: Drug Discovery Today
https://www.readbyqxmd.com/read/27568368/role-of-the-tyr270-residue-in-2-methyl-3-hydroxypyridine-5-carboxylic-acid-oxygenase-from-mesorhizobium-loti
#17
Jun Kobayashi, Hiromi Yoshida, Toshiharu Yagi, Shigehiro Kamitori, Hideyuki Hayashi, Kimihiko Mizutani, Nobuyuki Takahashi, Bunzo Mikami
The flavoenzyme 2-Methyl-3-hydroxypyridine-5-carboxylic acid oxygenase (MHPCO) catalyzes the cleavage of the pyridine ring of 2-methyl-3-hydroxypyridine-5-carboxylic acid (MHPC) in the presence of NADH, molecular oxygen, and water. MHPCO also catalyzes the NADH oxidation reaction uncoupled with ring opening in the absence of MHPC (the basal activity). The enzyme shows activity toward not only MHPC but also 5-hydroxynicotinic acid (5HN) and 5-pyridoxic acid (5PA). The reaction rate toward 5PA is extremely low (5% of the activity toward MHPC or 5HN)...
August 24, 2016: Journal of Bioscience and Bioengineering
https://www.readbyqxmd.com/read/27559694/regioselective-dichlorination-of-a-non-activated-aliphatic-carbon-atom-and-phenolic-bismethylation-by-a-multifunctional-fungal-flavoenzyme
#18
Pranatchareeya Chankhamjon, Yuta Tsunematsu, Mie Ishida-Ito, Yuzuka Sasa, Florian Meyer, Daniela Boettger-Schmidt, Barbara Urbansky, Klaus-Dieter Menzel, Kirstin Scherlach, Kenji Watanabe, Christian Hertweck
The regioselective functionalization of non-activated carbon atoms such as aliphatic halogenation is a major synthetic challenge. A novel multifunctional enzyme catalyzing the geminal dichlorination of a methyl group was discovered in Aspergillus oryzae (Koji mold), an important fungus that is widely used for Asian food fermentation. A biosynthetic pathway encoded on two different chromosomes yields mono- and dichlorinated polyketides (diaporthin derivatives), including the cytotoxic dichlorodiaporthin as the main product...
September 19, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27527619/therapeutic-approaches-using-riboflavin-in-mitochondrial-energy-metabolism-disorders
#19
REVIEW
Bárbara J Henriques, Tânia G Lucas, Cláudio M Gomes
Riboflavin, or vitamin B2, plays an important role in the cell as biological precursor of FAD and FMN, two important flavin cofactors which are essential for the structure and function of flavoproteins. Riboflavin has been used in therapeutic approaches of various inborn errors of metabolism, notably in metabolic disorders resulting either from defects in proteins involved in riboflavin metabolism and transport or from defects in flavoenzymes. The scope of this review is to provide an updated perspective of clinical cases in which riboflavin was used as a potential therapeutic agent in disorders affecting mitochondrial energy metabolism...
2016: Current Drug Targets
https://www.readbyqxmd.com/read/27487252/azoreductases-in-drug-metabolism
#20
Ali Ryan
Azoreductases are flavoenzymes that have been characterized in a range of prokaryotes and eukaryotes. Bacterial azoreductases are associated with the activation of two classes of drug, azo drugs for the treatment of inflammatory bowel disease and nitrofuran antibiotics. The mechanism of reduction of azo compounds is presented; it requires tautomerisation of the azo compound to a quinoneimine and provides a unifying mechanism for the reduction of azo and quinone substrates by azoreductases. The importance of further work in the characterization of azoreductases from enteric bacteria is highlighted to aid in the development of novel drugs for the treatment of colon related disorders...
August 3, 2016: British Journal of Pharmacology
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