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https://www.readbyqxmd.com/read/28532053/functionalized-fe3o4-graphene-oxide-nanocomposites-with-hairpin-aptamers-for-the-separation-and-preconcentration-of-trace-pb-2-from-biological-samples-prior-to-determination-by-icp-ms
#1
Mojtaba Shamsipur, Leila Farzin, Mahmoud Amouzadeh Tabrizi, Shahab Sheibani
Lead (Pb) as a topically poisonous metal represents a serious threat to the ecological environment and especially to human beings. Therefore, it is urgent to develop a rapid and reliable monitoring technique for this heavy metal in the environmental samples. In the present study, we have designed a selective and sensitive method for the determination of ultratrace contents of Pb(2+) in biological samples, based on the guanine (G)-quadruplex formed by the aptamer with hairpin structure and Pb(2+). For this purpose, Pb(2+) specific aptamer serving as affinity probe to capture and separate trace amounts of the analyte, was covalently linked to Fe3O4/graphene oxide (GO) surface by using a suitable cross-linking agent...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28531353/comprehensive-thermodynamic-profiling-for-the-binding-of-a-g-quadruplex-selective-indoloquinoline
#2
Andrea Funke, Klaus Weisz
Binding of a positively charged indoloquinoline derivative to a G-quadruplex formed by the G-rich promoter element of the c-MYC oncogene was subjected to a rigorous isothermal calorimetric analysis. Binding of the indoloquinoline is primarily enthalpy-driven but is also promoted by a favorable entropy term. Both binding enthalpy ΔH° and binding entropy ΔS° exhibit a noticeable temperature dependence with almost complete enthalpy-entropy compensation as a result of a negative change in heat capacity ΔCp°...
May 22, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28531122/microwave-assisted-synthesis-of-imidazo-4-5-f-1-10-phenanthroline-derivatives-as-apoptosis-inducers-in-chemotherapy-by-stabilizing-bcl-2-g-quadruplex-dna
#3
Li Li, Jie-Qiong Cao, Hui-Min Liu, Qiong Wu, Qiu-Hui Pan, Zhi-Ping Zeng, Yu-Tao Lan, Yu-Mei Li, Wen-Jie Mei, Xi-Cheng Wang, Wen-Jie Zheng
Herein, a series of imidazo[4,5-f][1,10] phenanthroline derivatives RPIP (PIP = imidazo [4,5-f][1,10] phenanthroline, R = NO₂, 1; CF₃, 2; Cl, 3; OH, 4) have been synthesized in yields of 82.3-94.7% at 100 °C under the irradiation of microwave. MTT assay has been utilized to evaluate the inhibitory activity (IC50) of these compounds against the growth of various tumor cells, and the results revealed that these compounds, especially 1, exhibited excellent inhibitory activity against the growth of A549 cells with IC50 of 15...
May 20, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28530833/discovery-of-small-molecules-for-repressing-cap-independent-translation-of-human-vascular-endothelial-growth-factor-hvegf-as-novel-anti-tumor-agents
#4
Shi-Ke Wang, Yue Wu, Xiao-Qin Wang, Guo-Tao Kuang, Qi Zhang, Shu-Ling Lin, Hui-Yun Liu, Jia-Heng Tan, Zhi-Shu Huang, Tian-Miao Ou
Angiogenesis is important in tumorigenesis and tumor progression. Human vascular endothelial growth factor (hVEGF) is an angiogenic growth factor that plays a crucial role in tumor progression. The G-rich region within the 5'-untranslated region (5'-UTR) of hVEGF mRNA can form a 'switchable' RNA G-quadruplex structure that is essential for a cap-independent translation initiation. We screened our small-molecule library for binders of this G-tract. One novel quinazoline derivative, compound 1, showed a significant specific interaction with the G-tract and destabilized the G-quadruplex structure...
May 22, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28530731/controllable-mn-doped-zno-nanorods-for-direct-assembly-of-a-photoelectrochemical-aptasensor
#5
Jing Li, Zhihui Dai, Hongbo Li
A label-free photoelectrochemical (PEC) aptasensor for K(+) was first constructed by direct self-assembly of the K(+) aptamer onto the electrodeposited Mn-doped ZnO nanorods. In the presence of K(+), the conformation of G-quadruplex changes to a K(+)-stabilized conformation, which can efficiently prevent the quercetin electron donor from reaching the functionalized photoanode, thus proportionately affecting the quercetin-enhanced photocurrent response. Under the optimal experimental conditions, the fabricated biosensor exhibited a linear response in the K(+) concentration range of 0...
May 22, 2017: Analyst
https://www.readbyqxmd.com/read/28525849/novel-photoelectrochemical-immunosensor-for-disease-related-protein-assisted-by-hemin-g-quadruplex-based-dnazyme-on-gold-nanoparticles-to-enhance-cathodic-photocurrent-on-p-cubi2o4-semiconductor
#6
Shuzhen Lv, Kangyao Zhang, Zhenzhen Lin, Dianping Tang
A novel p-type semiconductor material (p-CuBi2O4) is designed for the construction of split-type photoelectrochemical (PEC) immunosensor for alpha-fetoprotein (AFP) with the hemin assistant to enhance the cathodic photocurrent. Initially, the photocathode of PEC immunosensor is fabricated by p-CuBi2O4 on a layer of gold nanoparticles (AuNPs, as a front contact of p-CuBi2O4) to enhance the efficiency of charge separation. In the presence of target AFP, a sandwich-type immunoreaction was carried out in capture antibody-coated microplate by using detection antibody and hemin-based G-quadruplex (labeled on the AuNP) as the signal probe...
May 13, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28524432/solution-nmr-structure-of-a-ligand-hybrid-2-g-quadruplex-complex-reveals-rearrangements-that-affect-ligand-binding
#7
Julia Wirmer-Bartoschek, Lars Erik Bendel, Hendrik R A Jonker, J Tassilo Grün, Francesco Papi, Carla Bazzicalupi, Luigi Messori, Paola Gratteri, Harald Schwalbe
Telomeric G-quadruplexes have recently emerged as drug targets in cancer research. Herein, we present the first NMR structure of a telomeric DNA G-quadruplex that adopts the biologically relevant hybrid-2 conformation in a ligand-bound state. We solved the complex with a metalorganic gold(III) ligand that stabilizes G-quadruplexes. Analysis of the free and bound structures reveals structural changes in the capping region of the G-quadruplex. The ligand is sandwiched between one terminal G-tetrad and a flanking nucleotide...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28524354/an-aggregating-amphiphilic-squaraine-a-light-up-probe-that-discriminates-parallel-g-quadruplexes
#8
Vincenzo Grande, Filippo Doria, Mauro Freccero, Frank Würthner
G-quadruplexes (G4s) are peculiar DNA or RNA tertiary structures that are involved in the regulation of many biological events within mammalian cells, bacteria, and viruses. Although their role as versatile therapeutic targets has been emphasized for 35 years, G4 selectivity over ubiquitous double-stranded DNA/RNA, as well as G4 differentiation by small molecules, still remains challenging. Here, a new amphiphilic dicyanovinyl-substituted squaraine, SQgl, is reported to act as an NIR fluorescent light-up probe discriminating an extensive panel of parallel G4s while it is non-fluorescent in the aggregated state...
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28523907/unexpected-position-dependent-effects-of-ribose-g-quartets-in-g-quadruplexes
#9
Jun Zhou, Samir Amrane, Frédéric Rosu, Gilmar F Salgado, Yunqiang Bian, Hisae Tateishi-Karimata, Eric Largy, Dursun Nizam Korkut, Anne Bourdoncle, Daisuke Miyoshi, Jian Zhang, Huangxian Ju, Wei Wang, Naoki Sugimoto, Valérie Gabelica, Jean-Louis Mergny
To understand the role of ribose G-quartets and how they affect the properties of G-quadruplex structures, we studied three systems in which one, two, three, or four deoxyribose G-quartets were substituted with ribose G-quartets. These systems were a parallel DNA intramolecular G-quadruplex d(TTGGGTGGGTTGGGTGGGTT) and two tetramolecular G-quadruplexes d(TGGGT) and d(TGGGGT). Thermal denaturation experiments revealed that ribose G-quartets have position-dependent and cumulative effects on G-quadruplex stability...
May 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28521363/a-cisplatin-derivative-tetra-pt-bpy-as-an-oncotherapeutic-agent-for-targeting-alt-cancer
#10
Xiao-Hui Zheng, Xin Nie, Yiming Fang, Zepeng Zhang, Yingnan Xiao, Zongwan Mao, Haiying Liu, Jian Ren, Feng Wang, Lixin Xia, Junjiu Huang, Yong Zhao
Background: In approximately 15% of human cancers, telomere length is maintained independently of telomerase by the homologous recombination (HR)-mediated alternative lengthening of telomeres (ALT) pathway. Whether the ALT pathway can be exploited for therapeutic treatment remains unknown. The purpose of this study is to develop oncotherapeutic agent to target ALT cancers. Methods: Surface plasmon resonance assay, antibody to G-quadruplex, and fluorescence in situ hybridization (FISH) were used to discover Tetra-Pt(bpy), a cisplatin derivative that specifically targets telomeric G-quadruplex...
October 1, 2017: Journal of the National Cancer Institute
https://www.readbyqxmd.com/read/28515481/conserved-presence-of-g-quadruplex-forming-sequences-in-the-long-terminal-repeat-promoter-of-lentiviruses
#11
Rosalba Perrone, Enrico Lavezzo, Giorgio Palù, Sara N Richter
G-quadruplexes (G4s) are secondary structures of nucleic acids that epigenetically regulate cellular processes. In the human immunodeficiency lentivirus 1 (HIV-1), dynamic G4s are located in the unique viral LTR promoter. Folding of HIV-1 LTR G4s inhibits viral transcription; stabilization by G4 ligands intensifies this effect. Cellular proteins modulate viral transcription by inducing/unfolding LTR G4s. We here expanded our investigation on the presence of LTR G4s to all lentiviruses. G4s in the 5'-LTR U3 region were completely conserved in primate lentiviruses...
May 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28514170/discovery-of-novel-11-triazole-substituted-benzofuro-3-2-b-quinolone-derivatives-as-c-myc-g-quadruplex-specific-stabilizers-via-click-chemistry
#12
De-Ying Zeng, Guo-Tao Kuang, Shi-Ke Wang, Wang Peng, Shu-Ling Lin, Qi Zhang, Xiao-Xuan Su, Ming-Hao Hu, Honggen Wang, Jia-Heng Tan, Zhi-Shu Huang, Lian-Quan Gu, Tian-Miao Ou
The specificity of nucleic acids' binders is crucial for developing this kind of drugs, especially for novel G-quadruplexes' binders. Quindoline derivatives have been developed as G-quadruplex stabilizers with good interactive activities. In order to improve the selectivity and binding affinity of quindoline derivatives as c-myc G-quadruplex binding ligands, novel triazole containing benzofuroquinoline derivatives (T-BFQs) were designed and synthesized by using the 1,3-dipolar cycloaddition of a series of alkyne and azide building blocks...
May 17, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28513652/an-electrochemiluminescence-assay-for-sensitive-detection-of-methyltransferase-activity-in-different-cancer-cells-by-hybridization-chain-reaction-coupled-with-a-g-quadruplex-hemin-dnazyme-biosensing-strategy
#13
Hui Zhang, Zhihui Guo, Huilei Dong, Hongfei Chen, Chenxin Cai
In this work, a highly sensitive electrochemiluminescence (ECL) assay was fabricated for the detection of human DNA (cytosine-5)-methyltransferase1 (DNMT1) activity in cancer cells. The ECL assay coupled hybridization chain reaction with a G-quadruplex/hemin DNAzyme biosensing strategy. The ECL intensity changes (ΔI) allowed detection of DNMT1 activity down to 0.09 U mL(-1), and ΔI was proportional to the logarithm of the activity of DNMT1 within the range of 1.0 to 30.0 U mL(-1) in buffer solution. It also showed high sensitivity to DNMT1 activity in A549 cells, with a detection limit of about 2 cells...
May 17, 2017: Analyst
https://www.readbyqxmd.com/read/28513602/tetrahelical-structural-family-adopted-by-agcga-rich-regulatory-dna-regions
#14
Vojč Kocman, Janez Plavec
Here we describe AGCGA-quadruplexes, an unexpected addition to the well-known tetrahelical families, G-quadruplexes and i-motifs, that have been a focus of intense research due to their potential biological impact in G- and C-rich DNA regions, respectively. High-resolution structures determined by solution-state nuclear magnetic resonance (NMR) spectroscopy demonstrate that AGCGA-quadruplexes comprise four 5'-AGCGA-3' tracts and are stabilized by G-A and G-C base pairs forming GAGA- and GCGC-quartets, respectively...
May 17, 2017: Nature Communications
https://www.readbyqxmd.com/read/28513534/unraveling-prion-protein-interactions-with-aptamers-and-other-prp-binding-nucleic-acids
#15
REVIEW
Bruno Macedo, Yraima Cordeiro
Transmissible spongiform encephalopathies (TSEs) are a group of neurodegenerative disorders that affect humans and other mammals. The etiologic agents common to these diseases are misfolded conformations of the prion protein (PrP). The molecular mechanisms that trigger the structural conversion of the normal cellular PrP (PrP(C)) into the pathogenic conformer (PrP(Sc)) are still poorly understood. It is proposed that a molecular cofactor would act as a catalyst, lowering the activation energy of the conversion process, therefore favoring the transition of PrP(C) to PrP(Sc)...
May 17, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28510424/structure-dependent-binding-of-hnrnp-a1-to-telomere-rna
#16
Xiao Liu, Takumi Ishizuka, Hong-Liang Bao, Kei Wada, Yuuma Takada, Keisuke Iida, Kazuo Nagasawa, Danzhou Yang, Yan Xu
Telomeric repeat-containing RNA is a new non-coding RNA molecule that performs various bio-functions. Heterogeneous nuclear ribonucleoprotein (hnRNP) A1 is an RNA-binding protein involved in the telomere maintenance machinery. To date, little is known about how hnRNPA1 binds to telomeric RNA. In this study, we investigated the binding affinity and recognition mechanism of telomere RNA with the RNA recognition motif (RRM) of hnRNPA1. Using the photochemical crosslinking method, we showed that the telomere RNA G-quadruplex with loops is important in the interaction of telomere RNA with hnRNPA1...
May 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28506718/g-quadruplex-surveillance-in-bcl-2-gene-a-promising-therapeutic-intervention-in-cancer-treatment
#17
REVIEW
Pallabi Sengupta, Samit Chattopadhyay, Subhrangsu Chatterjee
BCL-2 overexpression promotes neoplastic cell expansion in cancers. Multiple noncanonical B-DNA motifs in the BCL-2 gene regulate selective modulation of its expression in normal and cancer cells. Three G-quadruplex topologies and one i-motif, in the vicinity of the P1 (major) promoter, stringently control its transcription. RNA quadruplexes and Z-DNA elements within translocation breakpoints of noncoding regions affect translation and promote oncogenic transformation of BCL-2 [e.g., t(14;18) translocation]...
May 12, 2017: Drug Discovery Today
https://www.readbyqxmd.com/read/28505453/adaptive-and-specific-recognition-of-telomeric-g-quadruplexes-via-polyvalency-induced-unstacking-of-binding-units
#18
Jibin Abraham Punnoose, Yue Ma, Yuanyuan Li, Mai Sakuma, Shankar Mandal, Kazuo Nagasawa, Hanbin Mao
Targeting DNA G-quadruplexes using small-molecule ligands has shown to modulate biological functions mediated by G-quadruplexes inside cells. Given >716,000 G-quadruplex hosting sites in human genome, the specific binding of ligands to quadruplex becomes problematic. Here, we innovated a polyvalency based mechanism to specifically target multiple telomeric G-quadruplexes. We synthesized a tetrameric telomestatin derivative and evaluated its complex polyvalent binding with multiple G-quadruplexes by single-molecule mechanical unfolding in laser tweezers...
May 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28503738/targeting-human-telomeric-g-quadruplex-dna-with-antitumour-natural-alkaloid-aristololactam-%C3%AE-d-glucoside-and-its-comparison-with-daunomycin
#19
Abhi Das, Sabyasachi Chatterjee, Gopinatha Suresh Kumar
Study on anticancer agents that act via stabilization of telomeric G-quadruplex DNA has emerged as novel and exciting field for anticancer drug discovery. The interaction of carbohydrate containing anticancer alkaloid aristololactam-β-D-glucoside (ADG) with human telomeric G-quadruplex DNA sequence was characterized by different biophysical techniques. The binding parameters were compared with daunomycin (DAN), a well-known chemotherapeutic drug. The Scatchard binding isotherms revealed noncooperative binding for both with the binding affinity values of (1...
May 15, 2017: Journal of Molecular Recognition: JMR
https://www.readbyqxmd.com/read/28499037/ball-with-hair-modular-functionalization-of-highly-stable-g-quadruplex-dna-nano-scaffolds-through-n2-guanine-modification
#20
Christopher Jacques Lech, Anh Tuân Phan
Functionalized nanoparticles have seen valuable applications, particularly in the delivery of therapeutic and diagnostic agents in biological systems. However, the manufacturing of such nano-scale systems with the consistency required for biological application can be challenging, as variation in size and shape have large influences in nanoparticle behavior in vivo. We report on the development of a versatile nano-scaffold based on the modular functionalization of a DNA G-quadruplex. DNA sequences are functionalized in a modular fashion using well-established phosphoramidite chemical synthesis with nucleotides containing modification of the amino (N2) position of the guanine base...
May 11, 2017: Nucleic Acids Research
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