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https://www.readbyqxmd.com/read/29767695/molybdenum
#1
Janet A Novotny, Catherine A Peterson
Molybdenum, a trace element essential for micro-organisms, plants, and animals, was discovered in 1778 by a Swedish chemist named Karl Scheele. Initially mistaken for lead, molybdenum was named after the Greek work molybdos, meaning lead-like. In the 1930s, it was recognized that ingestion of forage with high amounts of molybdenum by cattle caused a debilitating condition. In the 1950s, the essentiality of molybdenum was established with the discovery of the first molybdenum-containing enzymes. In humans, only 4 enzymes requiring molybdenum have been identified to date: sulfite oxidase, xanthine oxidase, aldehyde oxidase, and mitochondrial amidoxime-reducing component (mARC)...
May 1, 2018: Advances in Nutrition
https://www.readbyqxmd.com/read/29750861/determining-the-relative-binding-affinity-of-ricin-toxin-a-rta-inhibitors-by-using-molecular-docking-and-non-equilibrium-work
#2
Elton Chaves, Itácio Queiroz de Mello Padilha, Demetrius Antônio Machado Araújo, Gerd Bruno Rocha
Ricin is a ribosome-inactivating protein (RIP-type2) consisting of two subunits, Ricin Toxin A (RTA) and Ricin Toxin B (RTB). Due to its cytotoxicity, ricin has worried world authorities for its potential use as a chemical weapon; therefore, its inhibition is of great biotechnological interest. RTA is the target for inhibitor synthesis and pterin derivatives are promising candidates to inhibit it. In this study, we used a combination of molecular docking approach and fast steered molecular dynamics in order to assess the correlation between non-equilibrium work, 〈W〉, and IC50 of six RTA inhibitors...
May 11, 2018: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/29729023/photophysical-and-photochemical-properties-of-3-methylpterin-as-a-new-and-more-stable-pterin-type-photosensitizer
#3
Sandra Estébanez, Carolina Lorente, Teodoro S Kaufman, Enrique L Larghi, Andrés H Thomas, Mariana P Serrano
Pterin derivatives are heterocyclic compounds which are present in different biological systems. Neutral aqueous solutions of pterins presents acid-base and keto-enol equilibria. These compounds under UV-A radiation fluoresce, undergo photooxidation, generate reactive oxygen species, and photoinduce the oxidation of biological substrates. As photosensitizers, they may act through different mechanisms; mainly through an electron-transfer initiated process (type I mechanism), but they also produce singlet molecular oxygen (1 O2 ) upon irradiation (type II mechanism)...
May 4, 2018: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/29706069/biotransformation-of-sulfonamide-antibiotics-in-activated-sludge-formation-of-pterin-conjugates-leads-to-sustained-risk
#4
Stefan Achermann, Valeria Bianco, Cresten Mansfeldt, Bernadette Vogler, Boris A Kolvenbach, Philippe F-X Corvini, Kathrin Fenner
The presence of antibiotics in treated wastewater and consequently in surface and ground water resources raises concerns about the formation and spread of antibiotic resistance. Improving removal of antibiotics during wastewater treatment therefore is a prime objective of environmental engineering. Here we obtained a detailed picture of the fate of sulfonamide antibiotics during activated sludge treatment using a combination of analytical methods. We show that pterin-sulfonamide conjugates, which are formed when sulfonamides interact with their target enzyme to inhibit folic acid synthesis, represent a major biotransformation route for sulfonamides in laboratory batch experiments with activated sludge...
April 30, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29589922/mutagenesis-of-an-active-site-loop-in-tryptophan-hydroxylase-dra-matically-slows-the-formation-of-an-early-intermediate-in-catalysis
#5
Bishnu P Subedi, Paul F Fitzpatrick
Solution studies of the aromatic amino acid hydroxylases are consistent with the FeIVO intermediate not forming until both the amino acid and tetrahydropterin substrates have bound. Structural studies have shown that the positions of active-site loops differs significantly between the free enzyme and the enzyme-amino acid-tetrahydropterin complex. In tryptophan hydroxylase (TrpH) these mobile loops contain residues 124-134 and 365-371, with a key interaction involving Ile366. The I366N mutation in TrpH results in decreases of 1-2 orders of magnitude in the kcat and kcat/Km values...
March 28, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29575016/simultaneous-determination-of-twelve-polar-pteridines-including-dihydro-and-tetrahydropteridine-in-human-urine-by-hydrophilic-interaction-liquid-chromatography-with-tandem-mass-spectrometry
#6
Xin Xiong, Yuanyuan Zhang, Wenjing Zhang
Pteridines and its derivatives are important cofactors in the process of cell metabolism, and the level of urinary excretion of these compounds is considered as an important clinical criterion. In this work, a new separation method involving hydrophilic interaction chromatography (HILIC) with tandem mass spectrometric detection has been developed for the simultaneous analysis of twelve pteridines including oxidized, di- and tetrahydroforms, namely neopterin, 7,8-dihydroneopterin, biopterin, 7,8-dihydrobiopterin, 5,6,7,8-tetrahydrobiopterin, dimethylpterin, dimethyltetrahydropterin, pterin, isoxanthopterin, xanthopterin, sepiapterin and pterin-6-carboxylic acid in human urine without oxidative pretreatments...
March 25, 2018: Biomedical Chromatography: BMC
https://www.readbyqxmd.com/read/29571070/effect-of-pterin-impurities-on-the-fluorescence-and-photochemistry-of-commercial-folic-acid
#7
M Laura Dántola, M Noel Urrutia, Andrés H Thomas
Folic acid, or pteroyl‑l‑glutamic acid (PteGlu) is a conjugated pterin derivative that is used in dietary supplementation as a source of folates, a group of compounds essential for a variety of physiological functions in humans. Photochemistry of PteGlu is important because folates are not synthesized by mammals, undergo photodegradation and their deficiency is related to many diseases. We have demonstrated that usual commercial PteGlu is unpurified with the unconjugated oxidized pterins 6‑formylpterin (Fop) and 6‑carboxypterin (Cap)...
March 9, 2018: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/29437207/kinetic-control-in-the-regioselective-alkylation-of-pterin-sensitizers-a-synthetic-photochemical-and-theoretical-study-%C3%A2
#8
Niluksha Walalawela, Mariana Vignoni, María Noel Urrutia, Sarah J Belh, Edyta M Greer, Andrés H Thomas, Alexander Greer
Alkylation patterns and excited-state properties of pterins were examined both experimentally and theoretically. 2D NMR spectroscopy was used to characterize the pterin derivatives, revealing undoubtedly that the decyl chains were coupled to either the O4 or N3 sites on the pterin. At a temperature of 70°C, the pterin alkylation regioselectively favored the O4 over the N3. The O4 was also favored when using solvents, in which the reactants had increased solubility, namely N,N-dimethylformamide and N,N-dimethylacetamide, rather than solvents in which the reactants had very low solubility (tetrahydrofuran and dichloromethane)...
February 13, 2018: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/29410807/degradation-of-folic-acid-wastewater-by-electro-fenton-with-three-dimensional-electrode-and-its-kinetic-study
#9
Gu Xiaochao, Lu Xuebin, Tian Jin, Li Xiaoyun, Zhou Bin, Zheng Xujing, Xu Jin
The three-dimensional electro-Fenton method was used in the folic acid wastewater pretreatment process. In this study, we researched the degradation of folic acid and the effects of different parameters such as the air sparging rate, current density, pH and reaction time on chemical oxygen demand (COD) removal in folic acid wastewater. A four-level and four-factor orthogonal test was designed and optimal reaction conditions to pretreat folic acid wastewater by three-dimensional electrode were determined: air sparge rate 0...
January 2018: Royal Society Open Science
https://www.readbyqxmd.com/read/29396988/raf2-is-a-rubisco-assembly-factor-in-arabidopsis-thaliana
#10
Rikard Fristedt, Chen Hu, Nicole Wheatley, Laura M Roy, Rebekka M Wachter, Linda Savage, Jeremy Harbinson, David M Kramer, Sabeeha S Merchant, Todd Yeates, Roberta Croce
Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) catalyzes the reaction between gaseous carbon dioxide (CO2 ) and ribulose-1,5-bisphosphate. Although it is one of the most studied enzymes, the assembly mechanisms of the large hexadecameric RuBisCO is still emerging. In bacteria and in the C4 plant Zea mays, a protein with distant homology to pterin-4α-carbinolamine dehydratase (PCD) has recently been shown to be involved in RuBisCO assembly. However, studies of the homologous PCD-like protein (RAF2, RuBisCO assembly factor 2) in the C3 plant Arabidopsis thaliana (A...
April 2018: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/29380042/evaluation-of-pterin-a-promising-drug-candidate-from-cyanide-degrading-bacteria
#11
Ramasamy Mahendran, Murugesan Thandeeswaran, Gopikrishnan Kiran, Mani Arulkumar, K A Ayub Nawaz, Jayamanoharan Jabastin, Balraj Janani, Thomas Anto Thomas, Jayaraman Angayarkanni
Pterin is a member of the compounds known as pteridines. They have the same nucleus of 2-amino-4-hydroxypteridine (pterin); however, the side-chain is different at the position 6, and the state of oxidation of the ring may exist in different form viz. tetrahydro, dihydro, or a fully oxidized form. In the present study, the microorganisms able to utilize cyanide, and heavy metals have been tested for the efficient production of pterin compound. The soil samples contaminated with cyanide and heavy metals were collected from Salem steel industries, Tamil Nadu, India...
June 2018: Current Microbiology
https://www.readbyqxmd.com/read/29352942/comparative-study-of-molecular-recognition-of-folic-acid-subunits-with-cyclodextrins
#12
Magdalena Ceborska, Karolina Kędra-Królik, Aneta Aniela Kowalska, Małgorzata Koźbiał
The complexation of pteroic acid and pterine, subunits of folic acid, with native cyclodextrins (α‒, β‒, and γ‒CDs) was studied in solution (UV-vis), and in the solid state (thermal analysis, IR and Raman). UV-vis titrations at pH = 7.4 provided data regarding stoichiometry of the formed complexes as well as their associations constants. Stability of the complexes increases in the series: γ‒CD < β‒CD < α‒CD for pterine, and γ‒CD < α‒CD < β‒CD for pteroic acid...
March 15, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29303575/a-radical-intermediate-in-bacillus-subtilis-quee-during-turnover-with-the-substrate-analogue-6-carboxypterin
#13
Jarett Wilcoxen, Nathan A Bruender, Vahe Bandarian, R David Britt
7-Carboxy-7-deazaguanine (CDG) synthase (QueE), a member of the radical S-deoxyadenosyl-l-methionine (SAM) superfamily of enzymes, catalyzes a radical-mediated ring rearrangement required to convert 6-carboxy-5,6,7,8-tetrahydropterin (CPH4 ) into CDG, forming the 7-dezapurine precursor to all pyrrolopyrimidine metabolites. Members of the radical SAM superfamily bind SAM to a [4Fe-4S] cluster, leveraging the reductive cleavage of SAM by the cluster to produce a highly reactive 5'-deoxyadenosyl radical which initiates chemistry by H atom abstraction from the substrate...
February 7, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29285551/analeptic-agent-from-microbes-upon-cyanide-degradation
#14
REVIEW
Thandeeswaran Murugesan, Nisshanthini Durairaj, Mahendran Ramasamy, Karunya Jayaraman, Muthusamy Palaniswamy, Angayarkanni Jayaraman
Microbes being the initial form of life and ubiquitous in occurrence, they adapt to the environment quickly. The microbial metabolism undergoes alteration to ensure conducive environment either by degrading the toxic substances or producing toxins to protect themselves. The presence of cyanide waste triggers the cyanide degrading enzymes in the microbes which facilitate the microbes to utilize the cyanide for its growth. To enable the degradation of cyanide, the microbes also produce the necessary cofactors and enhancers catalyzing the degradation pathways...
February 2018: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29275262/design-synthesis-antibacterial-evaluation-and-molecular-docking-studies-of-some-new-quinoxaline-derivatives-targeting-dihyropteroate-synthase-enzyme
#15
Maryam A Z El-Attar, Rasha Y Elbayaa, Omaima G Shaaban, Nargues S Habib, Abeer E Abdel Wahab, Ibrahim A Abdelwahab, Soad A M El-Hawash
Development of new antimicrobial agents is a good solution to overcome drug-resistance problems. From this perspective, new quinoxaline derivatives bearing various bioactive heterocyclic moieties (thiadiazoles, oxadiazoles, pyrazoles and thiazoles) were designed and synthesized. The newly synthesized compounds were evaluated for their in vitro antibacterial activity against nine bacterial human pathogenic strains using the disc diffusion assay. In general, most of the synthesized compounds exhibited good antibacterial activities...
February 2018: Bioorganic Chemistry
https://www.readbyqxmd.com/read/29243345/deoxythymidine-pterin-fluorescent-adduct-formation-through-a-photosensitized-process
#16
Sandra Estébanez, Andrés H Thomas, Carolina Lorente
A new fluorescent compound was isolated from UVA-irradiated aqueous solutions containing pterin (Ptr) and 2'deoxythymidine (dT) in anaerobic conditions. Pterins are widespread in living systems in small amounts, but they are accumulated in some pathological situations. Under UVA radiation, pterins are photochemically active, fluorescent, and photosensitize the generation of singlet oxygen [1 O2 (1 Δg )]. The isolated compound was structurally characterized by using liquid chromatography coupled to tandem mass spectrometry, and its photophysical properties were studied with the time-correlated single-photon-counting technique...
February 5, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29184564/the-molybdenum-cofactor-biosynthesis-network-in-vivo-protein-protein-interactions-of-an-actin-associated-multi-protein-complex
#17
REVIEW
David Kaufholdt, Christin-Kirsty Baillie, Rieke Meinen, Ralf R Mendel, Robert Hänsch
Survival of plants and nearly all organisms depends on the pterin based molybdenum cofactor (Moco) as well as its effective biosynthesis and insertion into apo-enzymes. To this end, both the central Moco biosynthesis enzymes are characterized and the conserved four-step reaction pathway for Moco biosynthesis is well-understood. However, protection mechanisms to prevent degradation during biosynthesis as well as transfer of the highly oxygen sensitive Moco and its intermediates are not fully enlightened. The formation of protein complexes involving transient protein-protein interactions is an efficient strategy for protected metabolic channelling of sensitive molecules...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/29171692/8-mercaptoguanine-derivatives-as-inhibitors-of-dihydropteroate-synthase
#18
Matthew L Dennis, Michael D Lee, Jitendra R Harjani, Mohamed Ahmed, Aaron J DeBono, Noel P Pitcher, Zhong-Chang Wang, Sandeep Chhabra, Nicholas Barlow, Raphaël Rahmani, Ben Cleary, Olan Dolezal, Meghan Hattarki, Luigi Aurelio, Jeremy Shonberg, Bim Graham, Thomas S Peat, Jonathan B Baell, James D Swarbrick
Dihydropteroate synthase (DHPS) is an enzyme of the folate biosynthesis pathway, which catalyzes the formation of 7,8-dihydropteroate (DHPt) from 6-hydroxymethyl-7,8-dihydropterin pyrophosphate (DHPPP) and para-aminobenzoic acid (pABA). DHPS is the long-standing target of the sulfonamide class of antibiotics that compete with pABA. In the wake of sulfa drug resistance, targeting the structurally rigid (and more conserved) pterin site has been proposed as an alternate strategy to inhibit DHPS in wild-type and sulfa drug resistant strains...
February 6, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29111540/transcription-and-regulation-of-hepatitis-b-virus-genes-in-host-sperm-cells
#19
Ying Zhong, Dong-Ling Liu, Mohamed Morsi M Ahmed, Peng-Hao Li, Xiao-Ling Zhou, Qing-Dong Xie, Xiao-Qing Xu, Ting-Ting Han, Zhi-Wei Hou, Ji-Hua Huang, Lan Xu, Tian-Hua Huang
To investigate whether transcription of hepatitis B virus (HBV) gene occurs in human sperm, total RNA was extracted from sperm of patients with chronic HBV infection (test-1), from donor sperm transfected with a plasmid containing the full-length HBV genome (test-2), and from nontransfected donor sperm (control), used as the template for reverse transcription-polymerase chain reaction (RT-PCR). Positive bands for HBV DNA were observed in the test groups but not in the control. Next, to identify the role of host genes in regulating viral gene transcription in sperm, total RNA was extracted from 2-cell embryos derived from hamster oocytes fertilized in vitro by HBV-transfected (test) or nontransfected (control) human sperm and successively subjected to SMART-PCR, suppression subtractive hybridization, T/A cloning, bacterial amplification, microarray hybridization, sequencing and the Basic Local Alignment Search Tool (BLAST) search to isolate differentially expressed genes...
November 7, 2017: Asian Journal of Andrology
https://www.readbyqxmd.com/read/29068284/the-agrobacterium-tumefaciens-chey-like-protein-clar-regulates-biofilm-formation
#20
Nathan Feirer, DohHyun Kim, Jing Xu, Nico Fernandez, Christopher M Waters, Clay Fuqua
The switch from a motile, planktonic existence to an attached biofilm is a major bacterial lifestyle transition that is often mediated by complex regulatory pathways. In this report, we describe a CheY-like protein required for control of the motile-to-sessile switch in the plant pathogen Agrobacterium tumefaciens. This regulator, which we have designated ClaR, possesses two distinct CheY-like receiver (REC) domains and is involved in the negative regulation of biofilm formation, through production of the unipolar polysaccharide (UPP) adhesin and cellulose...
October 25, 2017: Microbiology
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