keyword
MENU ▼
Read by QxMD icon Read
search

pterins

keyword
https://www.readbyqxmd.com/read/29303575/a-radical-intermediate-in-bacillus-subtilis-quee-during-turnover-with-the-substrate-analog-6-carboxypterin
#1
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...
January 5, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29285551/analeptic-agent-from-microbes-upon-cyanide-degradation
#2
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...
December 28, 2017: 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
#3
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...
December 5, 2017: Bioorganic Chemistry
https://www.readbyqxmd.com/read/29243345/deoxythymidine-pterin-fluorescent-adduct-formation-by-a-photosensitized-proccess
#4
Sandra Estébanez, Andrés H Thomas, Carolina Lorente
A new fluorescent compound was isolated from UV-A irradiated aqueous solutions containing pterin (Ptr) and 2´deoxythymidine (dT) in anaerobic conditions. Pterins are widespread in the living systems in small amounts, but they are accumulated in some pathological situations. Under UV-A radiation, pterins are photochemically active, fluorescent and photosensitize the generation of singlet oxygen (1O2(1Δg)). The isolated compound was structurally characterized, by liquid chromatography coupled to tandem mass spectrometry, and its photophysical properties were studied by time correlated single photon counting technique...
December 15, 2017: 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
#5
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
#6
James Swarbrick, Matthew Dennis, Michael Lee, Jitendra Harjani, Mohamed Ahmed, Aaron Debono, Noel Pitcher, Zhong-Chang Wang, Sandeep Chhabra, Nicholas Barlow, Raphael Rahmani, Ben Cleary, Olan Dolezal, Meghan Hattarki, Luigi Aurelio, Jeremy Shonberg, Bim Graham, Tom Peat, Jonathan Baell
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...
November 24, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29111540/transcription-and-regulation-of-hepatitis-b-virus-genes-in-host-sperm-cells
#7
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
#8
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
https://www.readbyqxmd.com/read/29048424/analysis-of-human-cerebrospinal-fluid-monoamines-and-their-cofactors-by-hplc
#9
Marta Batllori, Marta Molero-Luis, Aida Ormazabal, Mercedes Casado, Cristina Sierra, Angels García-Cazorla, Manju Kurian, Simon Pope, Simon J Heales, Rafael Artuch
The presence of monoamines and their cofactors (the pterins and vitamin B6 (pyridoxal phosphate (PLP))) in human cerebrospinal fluid (CSF) can be used as indicators of the biosynthesis and turnover of dopamine and serotonin in the brain. In addition, abnormalities in the CSF levels of these molecules are associated with various neurological diseases, including genetic diseases leading to dopamine and serotonin deficiency. Here, we provide a set of quantitative high-performance liquid-chromatography (HPLC) approaches to determine CSF levels of monoamines and their cofactors...
November 2017: Nature Protocols
https://www.readbyqxmd.com/read/29032766/the-effects-of-drug-metabolizing-enzyme-inhibitors-on-hepatic-efflux-and-uptake-transporters
#10
Jonathan Cheong, Jason S Halladay, Jasleen K Sodhi, Emile Plise, Laurent Salphati
BACKGROUND: Non-selective chemical inhibitors of phase I and phase II enzymes are commonly used in in vitro metabolic studies to elucidate the biotransformation pathways of drugs. However, the inhibition of the inhibitors on efflux and uptake transporters is not well investigated, potentially leading to unexpected and ambiguous results in these studies. OBJECTIVE: The commonly used metabolizing enzyme inhibitors, 1-aminobenzotriazole (ABT), SKF-525A, pargyline, allopurinol, menadione, methimazole, piperine and raloxifene, were examined for their potential inhibition of the major hepatic ABC (ATP binding cassette) and SLC (solute carrier) transporters...
October 10, 2017: Drug Metabolism Letters
https://www.readbyqxmd.com/read/28926267/synthesis-and-analysis-of-bacterial-folate-metabolism-intermediates-and-antifolates
#11
Surendra Dawadi, Shannon L Kordus, Anthony D Baughn, Courtney C Aldrich
The mechanism of action of para-aminosalicylic acid (PAS), a drug used to treat drug-resistant tuberculosis (TB), has been confirmed through the first synthesis and biochemical characterization of its active metabolite 7. The synthesis features the coupling of N(2)-acetyl-6-formylpterin obtained from the degradation of folic acid and appropriately functionalized arylamines to form Schiff bases. The sequential chemoselective reduction of the imine and pterin ring led to the formation of dihydrofolate analogue 7 and two other dihydropteroate species...
October 6, 2017: Organic Letters
https://www.readbyqxmd.com/read/28874476/mechanisms-of-resistance-to-folate-pathway-inhibitors-in-burkholderia-pseudomallei-deviation-from-the-norm
#12
Nicole L Podnecky, Katherine A Rhodes, Takehiko Mima, Heather R Drew, Sunisa Chirakul, Vanaporn Wuthiekanun, James M Schupp, Derek S Sarovich, Bart J Currie, Paul Keim, Herbert P Schweizer
The trimethoprim and sulfamethoxazole combination, co-trimoxazole, plays a vital role in the treatment of Burkholderia pseudomallei infections. Previous studies demonstrated that the B. pseudomallei BpeEF-OprC efflux pump confers widespread trimethoprim resistance in clinical and environmental isolates, but this is not accompanied by significant resistance to co-trimoxazole. Using the excluded select-agent strain B. pseudomallei Bp82, we now show that in vitro acquired trimethoprim versus co-trimoxazole resistance is mainly mediated by constitutive BpeEF-OprC expression due to bpeT mutations or by BpeEF-OprC overexpression due to bpeS mutations...
September 5, 2017: MBio
https://www.readbyqxmd.com/read/28853183/differentiation-of-folate-receptor-positive-and-negative-cells-using-a-substrate-mimicking-fluorescent-probe
#13
Kaushik Pal, Angela Heinsch, Albrecht Berkessel, Apurba L Koner
Diagnosis and therapy exploiting overexpressed receptors on the cell surface is one important strategy in medicine. Determination of the over expression level of a particular receptor is prerequisite for it to be of clinical use. Differentiation between FR-positive (FR=folate receptor) and -negative cells via fluorescence microscopy using a substrate mimetic fluorophore is presented in this work. The strategy adopted here is not the classical FA-conjugated (FA=folic acid) fluorescent probe but a small and environment-sensitive pterin-based (pterin is part of folate, i...
August 29, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28820585/chemoenzymatic-assembly-of-isotopically-labeled-folates
#14
Antonio Angelastro, William M Dawson, Louis Y P Luk, E Joel Loveridge, Rudolf K Allemann
Pterin-containing natural products have diverse functions in life, but an efficient and easy scheme for their in vitro synthesis is not available. Here we report a chemoenzymatic 14-step, one-pot synthesis that can be used to generate (13)C- and (15)N-labeled dihydrofolates (H2F) from glucose, guanine, and p-aminobenzoyl-l-glutamic acid. This synthesis stands out from previous approaches to produce H2F in that the average yield of each step is >91% and it requires only a single purification step. The use of a one-pot reaction allowed us to overcome potential problems with individual steps during the synthesis...
September 6, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28742822/metal-ion-coordination-in-the-e-coli-nudix-hydrolase-dihydroneopterin-triphosphate-pyrophosphatase-new-clues-into-catalytic-mechanism
#15
Shannon E Hill, Elaine Nguyen, Chiamaka U Ukachukwu, Dana M Freeman, Stephen Quirk, Raquel L Lieberman
Dihydroneopterin triphosphate pyrophosphatase (DHNTPase), a member of the Mg2+ dependent Nudix hydrolase superfamily, is the recently-discovered enzyme that functions in the second step of the pterin branch of the folate biosynthetic pathway in E. coli. DHNTPase is of interest because inhibition of enzymes in bacterial folate biosynthetic pathways is a strategy for antibiotic development. We determined crystal structures of DHNTPase with and without activating, Mg2+-mimicking metals Co2+ and Ni2+. Four metal ions, identified by anomalous scattering, and stoichiometrically confirmed in solution by isothermal titration calorimetry, are held in place by Glu56 and Glu60 within the Nudix sequence motif, Glu117, waters, and a sulfate ion, of which the latter is further stabilized by a salt bridge with Lys7...
2017: PloS One
https://www.readbyqxmd.com/read/28737940/defining-the-structural-basis-for-allosteric-product-release-from-e-coli-dihydrofolate-reductase-using-nmr-relaxation-dispersion
#16
David Oyen, R Bryn Fenwick, Phillip C Aoto, Robyn L Stanfield, Ian A Wilson, H Jane Dyson, Peter E Wright
The rate-determining step in the catalytic cycle of E. coli dihydrofolate reductase is tetrahydrofolate (THF) product release, which can occur via an allosteric or an intrinsic pathway. The allosteric pathway, which becomes accessible when the reduced cofactor NADPH is bound, involves transient sampling of a higher energy conformational state, greatly increasing the product dissociation rate as compared to the intrinsic pathway that obtains when NADPH is absent. Although the kinetics of this process are known, the enzyme structure and the THF product conformation in the transiently formed excited state remain elusive...
August 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28707064/development-of-a-lateral-flow-dipstick-immunoassay-for-evaluation-of-folate-levels-in-maize
#17
Qiuju Liang, Chen Yi, Ling Jiang, Guiyu Tan, Chunyi Zhang, Baomin Wang
Folates (vitamin B9) are essential for all organisms as cofactors for one-carbon metabolism. However, measurement of folates is technically complicated and time-consuming. In this study, we developed a dipstick immunoassay using a folate-specific monoclonal antibody (mAb), allowing rapid and low-cost detection of folates. The indicator range of the dipstick for 5-formylterahydrofolate (5-CHO-THF), 5-methyltetrahydrofolate (5-CH3-THF) and their polyglutamyl forms was 100-200 ng mL(-1); moreover, no cross-reactivity was observed with tetrahydrofolate (THF) or 5,10-methenyltetrahydrofolate (5,10-CH=THF) at 500 ng mL(-1), or with the folate precursors pterin-6-COOH, p-aminobenzoate (pABA), and L-glutamate, or with the folate analogues methotrexate and 10-formyltetrahydrofolate (10-CHO-THF) at up to 1000 ng mL(-1)...
July 13, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28540433/altered-tetrahydrobiopterin-metabolism-in-patients-with-phenylalanine-hydroxylase-deficiency
#18
Francesca Nardecchia, Flavia Chiarotti, Claudia Carducci, Silvia Santagata, Giulia Valentini, Antonio Angeloni, Nenad Blau, Vincenzo Leuzzi
The tetrahydrobiopterin (BH4) cofactor is essential for the activity of various enzymes, including phenylalanine (Phe) hydroxylase. In phenylketonuria (PKU) patients, who are chronically exposed to high Phe levels, high urinary excretion of BH4 metabolites neopterin and biopterin is observed. The aim of this longitudinal study was to investigate consistence and variability of the urinary excretion of pterins (neopterin and biopterin) in PKU patients in relation to age and concomitant blood Phe and tyrosine levels...
July 2017: European Journal of Pediatrics
https://www.readbyqxmd.com/read/28496149/the-active-site-structure-and-catalytic-mechanism-of-arsenite-oxidase
#19
Thomas P Warelow, M Jake Pushie, Julien J H Cotelesage, Joanne M Santini, Graham N George
Arsenite oxidase is thought to be an ancient enzyme, originating before the divergence of the Archaea and the Bacteria. We have investigated the nature of the molybdenum active site of the arsenite oxidase from the Alphaproteobacterium Rhizobium sp. str. NT-26 using a combination of X-ray absorption spectroscopy and computational chemistry. Our analysis indicates an oxidized Mo(VI) active site with a structure that is far from equilibrium. We propose that this is an entatic state imposed by the protein on the active site through relative orientation of the two molybdopterin cofactors, in a variant of the Rây-Dutt twist of classical coordination chemistry, which we call the pterin twist hypothesis...
May 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28485428/exploring-micropollutant-biotransformation-in-three-freshwater-phytoplankton-species
#20
Michael A Stravs, Francesco Pomati, Juliane Hollender
Phytoplankton constitute an important component of surface water ecosystems; however little is known about their contribution to biotransformation of organic micropollutants. To elucidate biotransformation processes, batch experiments with two cyanobacterial species (Microcystis aeruginosa and Synechococcus sp.) and one green algal species (Chlamydomonas reinhardtii) were conducted. Twenty-four micropollutants were studied, including 15 fungicides and 9 pharmaceuticals. Online solid phase extraction (SPE) coupled with liquid chromatography (LC)-high resolution tandem mass spectrometry (HRMS/MS) was used together with suspect and nontarget screening to identify transformation products (TPs)...
June 21, 2017: Environmental Science. Processes & Impacts
keyword
keyword
94046
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"