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https://www.readbyqxmd.com/read/28731304/complex-formation-of-lead-ii-with-nucleotides-and-their-constituents
#1
Astrid Sigel, Bert P Operschall, Helmut Sigel
Lead is widely distributed in the environment; it is known to mankind for thousands of years and its toxicity is nowadays (again) well recognized, though on the molecular level only partly understood. One of the reasons for this shortcoming is that the coordination chemistry of the biologically important lead(II) is complicated due to the various coordination numbers it can adopt (CN = 4 to 10) as well as by the 6s2 electron lone pair which, with CN = 4, can shield one side of the Pb2+ coordination sphere. The chapter focuses on the properties of Pb2+ complexes formed with nucleotides and their constituents and derivatives...
April 10, 2017: Metal Ions in Life Sciences
https://www.readbyqxmd.com/read/28728523/structural-insights-into-the-binding-of-small-ligand-molecules-to-a-g-quadruplex-dna-located-in-the-hiv-1-promoter
#2
Petar M Mitrasinovic
Targeting guanine (G)-rich DNA sequences, folded into non-canonical G-quadruplex (G4) structures, by small ligand molecules is a promising strategy for gene therapy of various diseases. There is experimental proposal that, among eight studied ligands, nitidine chloride - NC and a benzo phenanthridine derivative - BPD have the highest binding affinities for such a sequence (5'-T(1)G(2)G(3)C(4)C(5)T(6)G(7)G(8)G(9)C(10)G(11)G(12)G(13)A(14)C(15)T(16)G(17)G(18)G(19)-3') in the HIV-1 promoter, indicating that an anti-HIV-1 prodrug may regulate the expression of the promoter...
July 20, 2017: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/28727736/persistent-damaged-bases-in-dna-allow-mutagenic-break-repair-in-escherichia-coli
#3
Jessica M Moore, Raul Correa, Susan M Rosenberg, P J Hastings
Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair...
July 20, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28727322/hfe-gene-polymorphism-defined-by-sequence-based-typing-of-the-brazilian-population-and-a-standardized-nomenclature-for-hfe-allele-sequences
#4
W N Campos, J D Massaro, A L C Martinelli, J A Halliwell, S G E Marsh, C T Mendes-Junior, E A Donadi
The HFE molecule controls iron uptake from gut, and defects in the molecule have been associated with iron overload, particularly in hereditary hemochromatosis. The HFE gene including both coding and boundary intronic regions were sequenced in 304 Brazilian individuals, encompassing healthy individuals and patients exhibiting hereditary or acquired iron overload. Six sites of variation were detected: i) H63D C > G in exon 2, ii) IVS2 (+4) T > C in intron 2, iii) a C > G transversion in intron 3, iv) C282Y G > A in exon 4, v) IVS4 (-44) T > C in intron 4, and vi) a new Guanine deletion (G > del) in intron 5, which were used for haplotype inference...
July 20, 2017: HLA
https://www.readbyqxmd.com/read/28726897/ultrafast-structural-dynamics-of-photoexcited-adenine
#5
Sayan Mondal, Mrinalini Puranik
We report deep UV initiated excited state dynamics of the canonical nucleobase adenine (Ade) through Resonance Raman (RR) intensity analysis. RR spectra of Ade at excitation wavelengths throughout the Bb absorption band in the 210-230 nm wavelength range are measured and subsequently converted to scattering cross-sections. The time-dependent wave packet (TDWP) formalism has been employed for self-consistent simulations of the resulting wavelength dependent Raman excitation profiles (REP) and absorption spectrum of Ade...
July 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28726394/human-cst-prefers-g-rich-but-not-necessarily-telomeric-sequences
#6
Robert A Hom, Deborah Sharon Wuttke
The human CST (CTC1-STN1-TEN1) heterotrimeric complex plays roles in both telomere maintenance and DNA replication through its ability to interact with ssDNA of a variety of sequences. The precise sequence specificity required to execute these functions is unknown. Telomere-binding proteins have been shown to specifically recognize key telomeric sequence motifs within ssDNA while accommodating non-specifically recognized sequences through conformationally plastic interfaces. To better understand the role CST plays in these processes, we have produced highly purified heterotrimer and elucidated the sequence requirements for CST recognition of ssDNA in vitro...
July 20, 2017: Biochemistry
https://www.readbyqxmd.com/read/28726304/retardation-of-antigen-release-from-dna-hydrogel-using-cholesterol-modified-dna-for-increased-antigen-specific-immune-response
#7
Yuka Umeki, Masaaki Saito, Yuki Takahashi, Yoshinobu Takakura, Makiya Nishikawa
Our previous study indicates that cationization of an antigen is effective for sustained release of both immunostimulatory DNA containing unmethylated cytosine-phosphate-guanine (CpG) dinucleotides, or CpG DNA, and antigen from a DNA hydrogel. Another approach to sustained antigen release would increase the applicability and versatility of the system. In this study, a hydrophobic interaction-based sustained release system of ovalbumin (OVA), a model antigen, from immunostimulatory CpG DNA hydrogel is developed by the use of cholesterol-modified DNA and urea-denatured OVA (udOVA)...
July 20, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28725233/g-quadruplex-in-plants-a-ubiquitous-regulatory-element-and-its-biological-relevance
#8
REVIEW
Vikas Yadav, Hemansi, Nayun Kim, Narendra Tuteja, Puja Yadav
G quadruplexes (G4) are higher-order DNA and RNA secondary structures formed by G-rich sequences that are built around tetrads of hydrogen-bonded guanine bases. Potential G4 quadruplex sequences have been identified in G-rich eukaryotic non-telomeric and telomeric genomic regions. Upon function, G4 formation is known to involve in chromatin remodeling, gene regulation and has been associated with genomic instability, genetic diseases and cancer progression. The natural role and biological validation of G4 structures is starting to be explored, and is of particular interest for the therapeutic interventions for human diseases...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28724198/direct-and-topoisomerase-ii-mediated-dna-damage-by-bis-3-chloropiperidines-the-importance-of-being-an-earnest-g
#9
Alice Sosic, Ivonne Zuravka, Nina-Katharina Schmitt, Angelica Miola, Richard Göttlich, Dan Fabris, Barbara Gatto
Bis-3-chloropiperidines are a new class of DNA-active compounds capable of alkylating nucleobases and inducing strand cleavage. In this report, we investigated the reactivity of these mustard-based agents with both single- and double-stranded DNA constructs. Polyacrylamide gel electrophoresis (PAGE) and electrospray ionization mass spectrometry (ESI-MS) were employed to obtain valuable insights into their mechanism at the molecular level and to investigate their time- and concentration-dependence. The results revealed the preferential formation of mono- and bifunctional adducts at nucleophilic guanine sites...
July 19, 2017: ChemMedChem
https://www.readbyqxmd.com/read/28723229/the-formation-of-nucleobases-from-the-ultraviolet-photoirradiation-of-purine-in-simple-astrophysical-ice-analogues
#10
Christopher K Materese, Michel Nuevo, Scott A Sandford
Nucleobases are the informational subunits of RNA and DNA and are essential to all known forms of life. The nucleobases can be divided into two groups of molecules: the pyrimidine-based compounds that include uracil, cytosine, and thymine, and the purine-based compounds that include adenine and guanine. Previous work in our laboratory has demonstrated that uracil, cytosine, thymine, and other nonbiological, less common nucleobases can form abiotically from the UV photoirradiation of pyrimidine in simple astrophysical ice analogues containing combinations of H2O, NH3, and CH4...
July 19, 2017: Astrobiology
https://www.readbyqxmd.com/read/28719194/molecular-modeling-of-the-major-dna-adduct-formed-from-the-food-mutagen-ochratoxin-a-in-nari-2-base-deletion-duplexes-impact-of-sequence-context-and-adduct-ionization-on-conformational-preference-and-mutagenicity
#11
Preetleen Kathuria, Purshotam Sharma, Richard A Manderville, Stacey D Wetmore
Exposure to ochratoxin A (OTA), a possible human carcinogen, leads to many different DNA mutations. As a first step toward understanding the structural basis of OTA-induced mutagenicity, the present work uses a robust computational approach and a slipped mutagenic intermediate model previously studied for C(8)-dG aromatic amine adducts to analyze the conformational features of post-replication 2-base deletion DNA duplexes containing OT-dG, the major OTA lesion at the C(8) position of guanine. Specifically, a total of 960 ns of molecular dynamics simulations (excluding trial simulations) were carried out on four OT-dG ionization states in three sequence contexts within oligomers containing the NarI recognition sequence, a known hotspot for deletion mutations induced by related adducts formed from known carcinogens...
July 18, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28718793/detection-of-guanine-and-adenine-using-an-aminated-reduced-graphene-oxide-functional-membrane-modified-glassy-carbon-electrode
#12
Di Li, Xiao-Lu Yang, Bao-Lin Xiao, Fang-Yong Geng, Jun Hong, Nader Sheibani, Ali Akbar Moosavi-Movahedi
A new electrochemical sensor based on a Nafion, aminated reduced graphene oxide and chitosan functional membrane-modified glassy carbon electrode was proposed for the simultaneous detection of adenine and guanine. Fourier transform-infrared spectrometry (FTIR), transmission electron microscopy (TEM), and electrochemical methods were utilized for the additional characterization of the membrane materials. The prepared electrode was utilized for the detection of guanine (G) and adenine (A). The anodic peak currents to G and A were linear in the concentrations ranging from 0...
July 18, 2017: Sensors
https://www.readbyqxmd.com/read/28716266/sativex%C3%A2-effects-on-promoter-methylation-and-on-cnr1-cnr2-expression-in-peripheral-blood-mononuclear-cells-of-progressive-multiple-sclerosis-patients
#13
Massimo Santoro, Massimiliano Mirabella, Chiara De Fino, Assunta Bianco, Matteo Lucchini, Francesco Losavio, Andrea Sabino, Viviana Nociti
Multiple sclerosis (MS) is a chronic demyelinating central nervous system (CNS) disease that involve oligodendrocyte loss and failure to remyelinate damaged brain areas causing a progressive neurological disability. Studies in MS mouse model suggest that cannabinoids ameliorate symptoms as spasticity, tremor and pain reducing inflammation via cannabinoid-mediated system. The aim of our study is to investigate the changes in cannabinoid type 1 (CNR1) and 2 (CNR2) receptors mRNA expression levels and promoter methylation in peripheral blood mononuclear cells (PBMCs) of MS secondary progressive (MSS-SP) patients treated with Sativex®...
August 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28715715/platinum-ii-and-palladium-ii-complexes-of-tridentate-hydrazone-based-ligands-as-selective-guanine-quadruplex-binders
#14
Alexander Schmidt, Rweetuparna Guha, Alexander Hepp, Jens Müller
Several tridentate hydrazone-based ligands, synthesized by a condensation reaction of either 2-(1-methylhydrazinyl)pyridine or 2-(1-methylhydrazinyl)quinoline with an aldehyde (picolinaldehyde, 1H-pyrrole-2-carbaldehyde, 2-mercaptobenzaldehyde, 2-aminobenzaldehyde) have been reacted with palladium(II) and platinum(II) salts and precursor complexes to yield nine new metal complexes. These planar complexes were investigated with respect to their capability to interact with guanine quadruplex DNA. Two sequences (H-telo, derived from the human telomeric sequence, and c-myc, representing an excerpt of the promoter region of the c-Myc oncogene) were investigated...
July 5, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28715629/structure-and-dynamics-of-electron-injection-and-charge-recombination-in-i-motif-dna-conjugates
#15
Taiga Fujii, Arun K Thazhathveetil, Ilyas Yildirim, Ryan M Young, Michael R Wasielewski, George C Schatz, Frederick D Lewis
The dynamics of electron injection have been investigated in intramolecular i-motif conjugates possessing stilbenediether (Sd) and perylenediimide (PDI) chromophores separated by either four or six hemi-protonated cytosine C-C base pairs assembled with synthetic loops. Circular dichroism spectra are consistent with the formation of i-motif structures in the absence or presence of Sd and PDI chromophores. The fluorescence of the Sd chromophore is essentially completely quenched by neighboring C-C base pairs, consistent with their function as an electron donor and electron acceptor, respectively...
July 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28712859/tyr42-phosphorylation-of-rhoa-gtpase-promotes-tumorigenesis-through-nuclear-factor-nf-%C3%AE%C2%BAb
#16
Jae-Gyu Kim, Kyoung-Chan Choi, Chang-Won Hong, Hwee-Seon Park, Eun-Kyoung Choi, Yong-Sun Kim, Jae-Bong Park
Dysregulation of reactive oxygen species (ROS) levels is implicated in the pathogenesis of several diseases, including cancer. However, the molecular mechanisms of ROS in tumorigenesis have not been clearly elucidated. Hydrogen peroxide activated nuclear factor-κB (NF-κB) and RhoA GTPase. In particular, we found that hydrogen peroxide phosphorylated RhoA at Tyr42 via Src. P-Ty42 residue of RhoA was a binding site of Vav2, a guanine nucleotide exchange factor (GEF) that activates p-Tyr42 RhoA. P-Tyr42 RhoA then bound to IκB kinase γ (IKKγ), leading IKKβ activation...
July 13, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28711634/role-of-epigenetic-modulation-in-cancer-stem-cell-fate
#17
REVIEW
Abhijeet Deshmukh, Mudra Binju, Frank Arfuso, Philip Newsholme, Arun Dharmarajan
A sub-population of the tumor micro-environment consists of cancer stem cells (CSCs), which are responsible for the initiation and recurrence of cancer. Recently, epigenetic processes such as DNA methylation, histone modification, and chromatin remodeling have been found to be involved in inducing epigenetic factors in CSCs. Most of these processes, such as DNA methylation, generally occur in the genome that is rich in Cytosine-Guanine repeat sequences, also known as CpG islands, which are distributed throughout the human genome...
July 12, 2017: International Journal of Biochemistry & Cell Biology
https://www.readbyqxmd.com/read/28710962/discovery-of-potent-molecular-chimera-cm358-to-treat-human-metastatic-melanoma
#18
Y Gilad, H Tuchinsky, G Ben-David, R Minnes, A Gancz, H Senderowitz, G Luboshits, M A Firer, G Gellerman
The resistance of cancer cells to chemotherapeutic agents, whether through intrinsic mechanisms or developed resistance, motivates the search for new chemotherapeutic strategies. In the present report, we demonstrate a facile synthetic strategy towards the discovery of new anti-cancer substances. This strategy is based on simple covalent coupling between known anti-cancer drugs, which results in novel 'chimeric' small molecules. One of these novel compounds, CM358, is the product of an amide bond formation between the known Topoisomerase II (Topo II) inhibitor amonafide (AM) and the known DNA mustard alkylator chlorambucil (CLB)...
June 29, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28708419/mechanisms-of-the-formation-of-adenine-guanine-and-their-analogues-in-uv-irradiated-mixed-nh3-h2o-molecular-ices-containing-purine
#19
Partha P Bera, Tamar Stein, Martin Head-Gordon, Timothy J Lee
We investigated the formation mechanisms of the nucleobases adenine and guanine and the nucleobase analogues hypoxanthine, xanthine, isoguanine, and 2,6-diaminopurine in a UV-irradiated mixed 10:1 H2O:NH3 ice seeded with precursor purine by using ab initio and density functional theory computations. Our quantum chemical investigations suggest that a multistep reaction mechanism involving purine cation, hydroxyl and amino radicals, together with water and ammonia, explains the experimentally obtained products in an independent study...
July 14, 2017: Astrobiology
https://www.readbyqxmd.com/read/28708393/selective-deamination-of-mutagens-by-a-mycobacterial-enzyme
#20
Vandana Gaded, Ruchi Anand
Structure-based methods are powerful tools that are being exploited to unravel new functions with therapeutic advantage. Here, we report the discovery of a new class of deaminases, predominantly found in mycobacterial species that act on the commercially important s-triazine class of compounds. The enzyme, Msd from Mycobacterium smegmatis was taken as a representative candidate from an evolutionarily conserved sub-group that possesses high density of Mycobacterium deaminases. Biochemical investigation reveals that Msd specifically acts on mutagenic nucleobases like 5-azacytosine and isoguanine, and does not accept natural bases as substrates...
July 14, 2017: Journal of the American Chemical Society
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