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https://www.readbyqxmd.com/read/29048885/correction-to-identification-of-the-tyroh-%C3%A2-radical-cation-in-the-flavoenzyme-trmfo
#1
Lipsa Nag, Pierre Sournia, Hannu Myllykallio, Ursula Liebl, Marten H Vos
No abstract text is available yet for this article.
October 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28985219/the-ins-and-outs-of-vanillyl-alcohol-oxidase-identification-of-ligand-migration-paths
#2
Gudrun Gygli, Maria Fátima Lucas, Victor Guallar, Willem J H van Berkel
Vanillyl alcohol oxidase (VAO) is a homo-octameric flavoenzyme belonging to the VAO/PCMH family. Each VAO subunit consists of two domains, the FAD-binding and the cap domain. VAO catalyses, among other reactions, the two-step conversion of p-creosol (2-methoxy-4-methylphenol) to vanillin (4-hydroxy-3-methoxybenzaldehyde). To elucidate how different ligands enter and exit the secluded active site, Monte Carlo based simulations have been performed. One entry/exit path via the subunit interface and two additional exit paths have been identified for phenolic ligands, all leading to the si side of FAD...
October 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28970893/characterization-of-the-flavoenzyme-xiak-as-an-n-hydroxylase-and-implications-in-indolosesquiterpene-diversification
#3
Qingbo Zhang, Huixian Li, Lu Yu, Yu Sun, Yiguang Zhu, Hanning Zhu, Liping Zhang, Shu-Ming Li, Yuemao Shen, Changlin Tian, Ang Li, Hung-Wen Liu, Changsheng Zhang
Flavoenzymes are ubiquitous in biological systems and catalyze a diverse range of chemical transformations. The flavoenzyme XiaK from the biosynthetic pathway of the indolosesquiterpene xiamycin A is demonstrated to mediate the in vivo biotransformation of xiamycin A into multiple products, including a chlorinated adduct as well as dimers characterized by C-N and N-N linkages that are hypothesized to form via radical-based mechanisms. Isolation and characterization of XiaK in vitro shows that it acts as a flavin-dependent N-hydroxylase that catalyzes the hydroxylation of xiamycin A at the carbazole nitrogen to form N-hydroxyxiamycin, a product which was overlooked in earlier in vivo experiments because its chemical and chromatographic properties are similar to those of oxiamycin...
July 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28947826/neferine-ameliorates-cardiomyoblast-apoptosis-induced-by-doxorubicin-possible-role-in-modulating-nadph-oxidase-ros-mediated-nf%C3%AE%C2%BAb-redox-signaling-cascade
#4
Lohanathan Bharathi Priya, Rathinasamy Baskaran, Chih-Yang Huang, Viswanadha Vijaya Padma
Doxorubicin (DOX) mediated cardiomyopathy is a major challenge in cancer chemotherapy. Redox-cycling of doxorubicin by flavoenzymes makes the heart more vulnerable to oxidative stress leading to cardiac dysfunction. The present study evaluates the role of neferine, a bisbenzylisoquinoline alkaloid, in curbing the molecular consequences of DOX-exposure in H9c2 cardiomyoblasts. Neferine pre-treatment increased cell viability upon DOX-exposure. DOX activates NADPH oxidase subunits, (p22phox, p47phox, gp91phox) as the primary event followed by peak in [Ca(2+)]i accumulation by 2 h, ROS by 3 h and activated ERK1/2 and p38 MAPKinases, time dependently along with the activation and translocation of NFκB and up-regulated COX2 and TNF-α expressions...
September 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28939686/species-specific-involvement-of-aldehyde-oxidase-and-xanthine-oxidase-in-the-metabolism-of-the-pyrimidine-containing-mglu5-negative-allosteric-modulator-vu0424238-auglurant
#5
Rachel D Crouch, Anna L Blobaum, Andrew S Felts, P Jeffrey Conn, Craig W Lindsley
Aldehyde oxidase (AO) and xanthine oxidase (XO) are molybdo-flavoenzymes that catalyze oxidation of aromatic azaheterocycles. Differences in AO activity have been reported among various species including rat, human, and monkey. Herein we report a species difference in the enzymes responsible for metabolism of mGlu5 NAM VU0424238 (VU238, auglurant). Hepatic S9 incubations with AO and XO specific inhibitors hydralazine and allopurinol indicated that rat and cynomolgus monkey both oxidized VU238 to the 6-oxopyrimidine metabolite M1 via an AO-mediated pathway, whereas secondary oxidation to the 2,6-dioxopyrimidine metabolite M2 was mediated predominantly by AO in monkey and XO in rat...
September 22, 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/28919416/identification-of-eukaryotic-udp-galactopyranose-mutase-inhibitors-using-the-thermofad-assay
#6
Julia S Martín Del Campo, Meital Eckshtain-Levi, Pablo Sobrado
Aspergillus fumigatus is a human pathogen responsible for deadly infections in immune-compromised patients. A potential strategy for treating A. fumigatus infections is by targeting the biosynthesis of cell wall components, such as galactofuranase, which is absent in humans. Galactofuranose biosynthesis is initiated by the flavoenzyme UDP-galactopyranose mutase (UGM), which converts UDP-galactopyranose (UDP-Galp) to UDP-galactofuranose (UDP-Galf). UGM requires the reduced form of the flavin for activity, which is obtained by reacting with NADPH...
November 4, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28890968/ultrafast-flavin-photoreduction-in-an-oxidized-animal-6-4-photolyase-through-an-unconventional-tryptophan-tetrad
#7
Ryan Martin, Fabien Lacombat, Agathe Espagne, Nadia Dozova, Pascal Plaza, Junpei Yamamoto, Pavel Müller, Klaus Brettel, Aurélien de la Lande
Photolyases are flavoenzymes repairing UV-induced lesions in DNA, which may be activated by a photoreduction of their FAD cofactor. In most photolyases, this photoreduction proceeds by electron transfer along a chain of three tryptophan (Trp) residues, connecting the flavin to the protein surface. Much less studied, animal (6-4) photolyases (repairing pyrimidine-pyrimidone (6-4) photoproducts) are particularly interesting as they were recently shown to have a longer electron transfer chain, counting four Trp residues...
September 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28802828/photolyase-dynamics-and-electron-transfer-mechanisms-of-dna-repair
#8
REVIEW
Meng Zhang, Lijuan Wang, Dongping Zhong
Photolyase, a flavoenzyme containing flavin adenine dinucleotide (FAD) molecule as a catalytic cofactor, repairs UV-induced DNA damage of cyclobutane pyrimidine dimer (CPD) and pyrimidine-pyrimidone (6-4) photoproduct using blue light. The FAD cofactor, conserved in the whole protein superfamily of photolyase/cryptochromes, adopts a unique folded configuration at the active site that plays a critical functional role in DNA repair. Here, we review our comprehensive characterization of the dynamics of flavin cofactor and its repair photocycles by different classes of photolyases on the most fundamental level...
October 15, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28796306/enzyme-activation-with-a-synthetic-catalytic-co-enzyme-intermediate-nucleotide-methylation-by-flavoenzymes
#9
Charles Bou-Nader, David Cornu, Vincent Guerineau, Thibault Fogeron, Marc Fontecave, Djemel Hamdane
To facilitate production of functional enzymes and to study their mechanisms, especially in the complex cases of coenzyme-dependent systems, activation of an inactive apoenzyme preparation with a catalytically competent coenzyme intermediate is an attractive strategy. This is illustrated with the simple chemical synthesis of a flavin-methylene iminium compound previously proposed as a key intermediate in the catalytic cycle of several important flavoenzymes involved in nucleic acid metabolism. Reconstitution of both flavin-dependent RNA methyltransferase and thymidylate synthase apoproteins with this synthetic compound led to active enzymes for the C5-uracil methylation within their respective transfer RNA and dUMP substrate...
October 2, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28782586/breaking-the-mirror-l-amino-acid-deaminase-a-novel-stereoselective-biocatalyst
#10
REVIEW
Gianluca Molla, Roberta Melis, Loredano Pollegioni
Enantiomerically pure amino acids are of increasing interest for the fine chemical, agrochemicals and pharmaceutical industries. During past years l-amino acids have been produced from deracemization of dl-solution employing the stereoselective flavoenzyme d-amino acid oxidase. On the other hand, the isolation of corresponding d-isomer was hampered by the scarce availability of a suitable l-amino acid oxidase activity. On this side, l-amino acid deaminase (LAAD), only present in the Proteus bacteria, represents a suitable alternative...
November 1, 2017: Biotechnology Advances
https://www.readbyqxmd.com/read/28750088/a-single-nucleotide-polymorphism-causes-enhanced-radical-oxygen-species-production-by-human-aldehyde-oxidase
#11
Alessandro Foti, Frank Dorendorf, Silke Leimkühler
Aldehyde oxidases (AOXs) are molybdo-flavoenzymes characterized by broad substrate specificity, oxidizing aromatic/aliphatic aldehydes into the corresponding carboxylic acids and hydroxylating various heteroaromatic rings. The enzymes use oxygen as the terminal electron acceptor and produce reduced oxygen species during turnover. The physiological function of mammalian AOX isoenzymes is still unclear, however, human AOX (hAOX1) is an emerging enzyme in phase-I drug metabolism. Indeed, the number of xenobiotics acting as hAOX1 substrates is increasing...
2017: PloS One
https://www.readbyqxmd.com/read/28745052/identification-of-the-tyroh-%C3%A2-radical-cation-in-the-flavoenzyme-trmfo
#12
Lipsa Nag, Pierre Sournia, Hannu Myllykallio, Ursula Liebl, Marten H Vos
Tyrosine (TyrOH) and tryptophan radicals play important roles as intermediates in biochemical charge-transfer reactions. Tryptophanyl radicals have been observed both in their protonated cation form and in their unprotonated neutral form, but to date, tyrosyl radicals have only been observed in their unprotonated form. With a genetically modified form of the flavoenzyme TrmFO as a suitable model system and using ultrafast fluorescence and absorption spectroscopy, we characterize its protonated precursor TyrOH(•+), and we show this species to have a distinct visible absorption band and a transition moment that we suggest to lie close to the phenol symmetry axis...
August 8, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28712849/structure-function-and-mechanism-of-proline-utilization-a-puta
#13
REVIEW
Li-Kai Liu, Donald F Becker, John J Tanner
Proline has important roles in multiple biological processes such as cellular bioenergetics, cell growth, oxidative and osmotic stress response, protein folding and stability, and redox signaling. The proline catabolic pathway, which forms glutamate, enables organisms to utilize proline as a carbon, nitrogen, and energy source. FAD-dependent proline dehydrogenase (PRODH) and NAD(+)-dependent glutamate semialdehyde dehydrogenase (GSALDH) convert proline to glutamate in two sequential oxidative steps. Depletion of PRODH and GSALDH in humans leads to hyperprolinemia, which is associated with mental disorders such as schizophrenia...
October 15, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28694766/flavoenzyme-mediated-reduction-reactions-and-antitumor-activity-of-nitrogen-containing-tetracyclic-ortho-quinone-compounds-and-their-nitrated-derivatives
#14
Milda Peciukaityte-Alksne, Jonas Šarlauskas, Lina Miseviciene, Audrone Maroziene, Narimantas Cenas, Kastis Krikštopaitis, Zita Staniulyte, Žilvinas Anusevicius
Nitrogen-based tetracyclic ortho-quinones (naphtho[1'2':4.5]imidazo[1,2-a]pyridine-5,6-diones, NPDOs) and their nitro-substituted derivatives (nitro-(P)NPDOs) were obtained by condensation of substituted 2,3-dichloro-1,4-naphthoquinones with 2-amino-pyridine and -pyrimidine and nitration at an elevated temperature. The structural features of the compounds as well as their global and regional electrophilic potency were characterized by means of DFT computation. The compounds were highly reactive substrates of single- and two-electron (hydride) - transferring P-450R (CPR; EC 1...
2017: EXCLI journal
https://www.readbyqxmd.com/read/28666740/the-dihydroorotate-dehydrogenases-past-and-present
#15
REVIEW
Renata A G Reis, Felipe Antunes Calil, Patricia Rosa Feliciano, Matheus Pinto Pinheiro, M Cristina Nonato
The flavoenzyme dihydroorotate dehydrogenase catalyzes the stereoselective oxidation of (S)-dihydroorotate to orotate in the fourth of the six conserved enzymatic reactions involved in the de novo pyrimidine biosynthetic pathway. Inhibition of pyrimidine metabolism by selectively targeting DHODHs has been exploited in the development of new therapies against cancer, immunological disorders, bacterial and viral infections, and parasitic diseases. Through a chronological narrative, this review summarizes the efforts of the scientific community to achieve our current understanding of structural and biochemical properties of DHODHs...
June 27, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28661684/ruta-catalyzed-oxidative-cleavage-of-the-uracil-amide-involves-formation-of-a-flavin-n5-oxide
#16
Sanjoy Adak, Tadhg P Begley
RutA is a novel flavoenzyme on the uracil catabolic pathway that catalyzes uracil ring opening by a unique amide oxidation reaction. Here we provide evidence that this reaction also involves the formation of a flavin-N5-oxide.
July 25, 2017: Biochemistry
https://www.readbyqxmd.com/read/28652025/multiple-functionalities-of-reduced-flavin-in-the-non-redox-reaction-catalyzed-by-udp-galactopyranose-mutase
#17
REVIEW
Pablo Sobrado, John J Tanner
Flavin cofactors are widely used by enzymes to catalyze a broad range of chemical reactions. Traditionally, flavins in enzymes are regarded as redox centers, which enable enzymes to catalyze the oxidation or reduction of substrates. However, a new class of flavoenzyme has emerged over the past quarter century in which the flavin functions as a catalytic center in a non-redox reaction. Here we introduce the unifying concept of flavin hot spots to understand and categorize the mechanisms and reactivities of both traditional and noncanonical flavoenzymes...
October 15, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28643772/cryptic-indole-hydroxylation-by-a-non-canonical-terpenoid-cyclase-parallels-bacterial-xenobiotic-detoxification
#18
Susann Kugel, Martin Baunach, Philipp Baer, Mie Ishida-Ito, Srividhya Sundaram, Zhongli Xu, Michael Groll, Christian Hertweck
Terpenoid natural products comprise a wide range of molecular architectures that typically result from C-C bond formations catalysed by classical type I/II terpene cyclases. However, the molecular diversity of biologically active terpenoids is substantially increased by fully unrelated, non-canonical terpenoid cyclases. Their evolutionary origin has remained enigmatic. Here we report the in vitro reconstitution of an unusual flavin-dependent bacterial indoloterpenoid cyclase, XiaF, together with a designated flavoenzyme-reductase (XiaP) that mediates a key step in xiamycin biosynthesis...
June 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28640638/enzyme-mediated-conversion-of-flavin-adenine-dinucleotide-fad-to-8-formyl-fad-in-formate-oxidase-results-in-a-modified-cofactor-with-enhanced-catalytic-properties
#19
John M Robbins, Michael G Souffrant, Donald Hamelberg, Giovanni Gadda, Andreas S Bommarius
Flavins, including flavin adenine dinucleotide (FAD), are fundamental catalytic cofactors that are responsible for the redox functionality of a diverse set of proteins. Alternatively, modified flavin analogues are rarely found in nature as their incorporation typically results in inactivation of flavoproteins, thus leading to the disruption of important cellular pathways. Here, we report that the fungal flavoenzyme formate oxidase (FOX) catalyzes the slow conversion of noncovalently bound FAD to 8-formyl FAD and that this conversion results in a nearly 10-fold increase in formate oxidase activity...
July 25, 2017: Biochemistry
https://www.readbyqxmd.com/read/28602956/structure-function-studies-of-mical-the-unusual-multidomain-flavoenzyme-involved-in-actin-cytoskeleton-dynamics
#20
REVIEW
Maria Antonietta Vanoni
MICAL (from the Molecule Interacting with CasL) indicates a family of multidomain proteins conserved from insects to humans, which are increasingly attracting attention for their participation in the control of actin cytoskeleton dynamics, and, therefore, in the several related key processes in health and disease. MICAL is unique among actin binding proteins because it catalyzes a NADPH-dependent F-actin depolymerizing reaction. This unprecedented reaction is associated with its N-terminal FAD-containing domain that is structurally related to p-hydroxybenzoate hydroxylase, the prototype of aromatic monooxygenases, but catalyzes a strong NADPH oxidase activity in the free state...
June 8, 2017: Archives of Biochemistry and Biophysics
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