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1.
J Hazard Mater ; 477: 135292, 2024 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-39059292

RESUMEN

Laccases are the most commonly used agents for the treatment of phenolic pollutants. To address the instability and high cost of natural laccases, we investigated nucleobase-modulated copper nanomaterial with laccase-like activity. Various nucleobases, including adenine, guanine, cytosine, and thymine, were investigated as templates for Cu2+ reduction and copper nanomaterials formation due to their coordination capacity. By comparing structure and catalytic activity, the cytosine-mediated copper nanomaterial (C-Cu) had the best laccase-like activity and other nucleobase-templated copper nanomaterials exhibited low catalytic activity under the same conditions. The mechanism of nucleobase regulation of the catalytic activity of copper nanomaterials was further analyzed using X-ray photoelectron spectroscopy and density functional theory. The possible catalytic mechanisms of C-Cu, including substrate adsorption, substrate oxidation, oxygen binding, and oxygen reduction, were proposed. Remarkably, nucleobase-modulated copper nanozymes showed high stability and catalytic oxidation performance at various pH values, temperatures, long-term storage, and high salinity. In combination with electrochemical techniques, a portable electrochemical sensor for measuring phenolic pollutants was developed. This novel sensor exhibited a good linear response to catechol (10-1000 µM) with a limit of detection of 1.8 µM and excellent selectivity and anti-interference ability. This study provides not only a new strategy for the regulation of the laccase-like activity of copper nanomaterials but also a novel tool for the effective removal and low-cost detection of phenolic pollutants.


Asunto(s)
Cobre , Lacasa , Nanoestructuras , Contaminantes Químicos del Agua , Cobre/química , Lacasa/química , Lacasa/metabolismo , Nanoestructuras/química , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/química , Oxidación-Reducción , Fenoles/química , Fenoles/análisis , Catálisis , Técnicas Electroquímicas , Citosina/química , Catecoles/química , Adenina/química , Adenina/análisis , Guanina/química , Guanina/análisis
2.
Biosens Bioelectron ; 226: 115104, 2023 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-36764126

RESUMEN

The separation of the superimposed electrochemical signals of intracellular guanine (G) and xanthine (X) is difficult, which is great obstacle to the application of cell electrochemistry. In this paper, independent functional modules, G-functional module (G-FM) and X-functional module (X-FM), were constructed by molecular imprinting technology for sensitive detection of G and X without mutual interference, then integrated in dual-functional module cellular electrochemical sensing platform (DMCEP) as signal sensing units. DMCEP transmitted signals of G and X in cells synchronously to two windows by two signal sensing channels, and achieved the separation of superimposed signals of G and X in cells. DMCEP exhibited satisfactory reproducibility with relative standard deviation (RSD) of 3.10 and 2.22 %, repeatability with RSD of 3.72 and 3.05 % for G and X detection, and detection limit 0.05 µΜ for G and 0.06 µΜ for X. Good linear relationships between cell concentrations and the signals of G and X on DMCEP were shown in range of 0.75-85 × 106 and 3-85 × 106 cells/mL, respectively. The growth of MCF-7 cells was tracked by DMCEP, and showed consistent trend with the cell counting method, while the change of cell viability from lag to logarithmic phase captured by DMCEP was earlier than that of cell counting method. This strategy provided the foundation for the establishment of the cell viability electrochemical detection method, and new insights into the simultaneous recording of other analyses with superimposed peak positions and the simultaneous tracking of multiple biomarkers.


Asunto(s)
Técnicas Biosensibles , Guanina , Humanos , Xantina , Guanina/análisis , Reproducibilidad de los Resultados , Células MCF-7 , Técnicas Electroquímicas , Límite de Detección , Electrodos
3.
Chemosphere ; 309(Pt 1): 136763, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36209857

RESUMEN

Halobenzoquinones (HBQs) are an emerging class of drinking water disinfection byproducts that have been predicted as bladder carcinogens. However, data on the genotoxicity of HBQs are still scarce. This study performed a quantitative structure-toxicity relationship (QSTR) analysis of HBQ isomers on DNA reactivity and genotoxicity. The interaction of HBQs with calf thymus DNA (ct-DNA) was studied using multi-spectroscopic and molecular docking techniques. UV-Vis absorption spectra observed a significant hyperchromic effect with the increase of HBQ concentration. The fluorescence intensity of both probe-ct-DNA decreased with the increasing concentration of HBQs, indicating that the interaction mode between each HBQs and DNA was quite complicated, and there were both minor groove binding and intercalation binding. Molecular docking showed that HBQs interacted with DNA predominantly via hydrogen bond at guanine-rich areas in the minor groove of DNA. The genotoxicity of HBQs on human hepatocytes (L-02) was evaluated by micronucleus test, and the results showed that HBQs could cause significant chromosomal damage. The rank order of HBQ isomers on DNA reactivity and genotoxicity was 2,5-HBQs > their corresponding 2,6-HBQs. QSTR analysis found that dipole moment is the key structural descriptor influencing both DNA reactivity and genotoxicity of HBQ isomers. This study suggested that HBQs have caused genotoxicity which was influenced by their isomeric effects, warranting a comprehensive understanding of the genotoxic and carcinogenic risks associated with HBQs exposure.


Asunto(s)
Agua Potable , Humanos , Agua Potable/análisis , Simulación del Acoplamiento Molecular , Benzoquinonas/química , Daño del ADN , ADN , Carcinógenos/análisis , Guanina/análisis
4.
Mikrochim Acta ; 188(11): 406, 2021 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-34734344

RESUMEN

Raman spectroscopy is a powerful method to characterize molecules in various media. Although surface-enhanced Raman scattering (SERS) is often employed to compensate for the intrinsically poor sensitivity of Raman spectroscopy, there remain serious tasks, such as simple preparations of SERS substrates, sensitivity control, and reproducible measurements. Here, we propose freezing as an efficient way to overcome these problems in SERS measurements using DNA bases as model targets. Solutes are expelled from ice crystals and concentrated in the liquid phase upon freezing. Silver nanoparticles (AgNPs) are also concentrated in the liquid phase to aggregate with Raman target analytes. The SERS signal intensity is maximized when the AgNP concentration exceeds the critical aggregation value. Freezing allows up to 5000 times enhancements of the SERS signal. Thus, an efficient SERS platform is prepared by simple freezing. The simultaneous detection of four DNA bases effectively eliminates variations of signal intensities and allows the reliable determination of concentration ratios.


Asunto(s)
Adenina/análisis , Citosina/análisis , Guanina/análisis , Nanopartículas del Metal/química , Timidina/análisis , Cerveza/análisis , Crioprotectores/química , Congelación , Glicerol/química , Límite de Detección , Plata/química , Espectrometría Raman/métodos , Sacarosa/química
5.
Mikrochim Acta ; 188(8): 276, 2021 07 28.
Artículo en Inglés | MEDLINE | ID: mdl-34319444

RESUMEN

A rapid and sensitive electrochemical sensing platform is reported based on bimetallic gold-platinum nanoclusters (AuPtNCs) dispersed on reduced graphene oxide (rGO) for the simultaneous detection of guanine and adenine using square wave voltammetry (SWV). The synthesis of AuPtNCs-rGO nanocomposite was achieved by a simultaneous reduction of graphene oxide (GO) and metal ions (Au3+ and Pt4+) in an aqueous solution. The developed AuPtNCs-rGO electrochemical sensor with the optimized 50:50 bimetallic (Au:Pt) nanoclusters exhibited an outstanding electrocatalytic performance towards the simultaneous oxidation of guanine and adenine without the aid of any enzymes or mediators in physiological pH. The electrochemical sensor platform showed low detection limits of 60 nM and 100 nM (S/N = 3) for guanine and adenine, respectively, with high sensitivity and an extensive linear range from 1.0 µM to 0.2 mM for both guanine and adenine. The interference from the most common electrochemically active interferents, including ascorbic acid, uric acid, and dopamine, was almost negligible. The simultaneous sensing of guanine and adenine in denatured Salmon Sperm DNA sample was successfully achieved using the proposed platform, showing that the AuPtNCs-rGO nanocomposite could provide auspicious clinical diagnosis and biomedical applications.


Asunto(s)
Adenina/análisis , Aleaciones/química , Grafito/química , Guanina/análisis , Nanopartículas del Metal/química , Nanocompuestos/química , Animales , Ácido Ascórbico/química , Técnicas Biosensibles , ADN/análisis , Dopamina/química , Técnicas Electroquímicas , Electrodos , Oro/química , Límite de Detección , Masculino , Oxidación-Reducción , Platino (Metal)/química , Salmón , Espermatozoides/química , Ácido Úrico/química
6.
J Sep Sci ; 44(16): 3080-3088, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34165890

RESUMEN

A simple and rapid ultra-high-performance liquid chromatography coupled with mass spectrometry method was developed for acyclovir and its metabolite 9-carboxymethoxymethylguanine in human serum. After precipitation of serum samples with 0.1% formic acid in acetonitrile/methanol (40:60, v/v), components were separated on a Luna Omega C18 column (1.6 µm; 2.1 × 150 mm) at 40°C. Mobile phase A (2 mmol/L ammonium acetate, 0.1% formic acid in 5% acetonitrile, v/v/v) and mobile phase B (2 mmol/L ammonium acetate, 0.1% formic acid in 95% acetonitrile, v/v/v) were used for gradient elution. A linear calibration curve was obtained over the range of 0.05-50 mg/L, and the correlation coefficients were better than 0.999. The limit of quantitation was 0.05 mg/L for both analytes. The intra- and interday accuracy and precision at three concentration levels ranged between 1.6 and 13.3%, and recoveries were achieved with a range between 92.2 and 114.2%. This method was developed and validated for the therapeutic monitoring of acyclovir in patients.


Asunto(s)
Aciclovir/análisis , Cromatografía Líquida de Alta Presión/métodos , Guanina/análogos & derivados , Espectrometría de Masas en Tándem/métodos , Acetonitrilos/química , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Calibración , Técnicas de Química Analítica/normas , Femenino , Formiatos/química , Guanina/análisis , Humanos , Límite de Detección , Masculino , Espectrometría de Masas , Persona de Mediana Edad , Control de Calidad , Reproducibilidad de los Resultados , Adulto Joven
7.
Rapid Commun Mass Spectrom ; 35(13): e9095, 2021 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-33821547

RESUMEN

RATIONALE: As a new approach to DNA adductomics, we directly reacted intact, double-stranded (ds)-DNA under warm conditions with an alkylating mass tag followed by analysis by liquid chromatography/mass spectrometry. This method is based on the tendency of adducted nucleobases to locally disrupt the DNA structure (forming a "DNA bubble") potentially increasing exposure of their nucleophilic (including active hydrogen) sites for preferential alkylation. Also encouraging this strategy is that the scope of nucleotide excision repair is very broad, and this system primarily recognizes DNA bubbles. METHODS: A cationic xylyl (CAX) mass tag with limited nonpolarity was selected to increase the retention of polar adducts in reversed-phase high-performance liquid chromatography (HPLC) for more detectability while maintaining resolution. We thereby detected a diversity of DNA adducts (mostly polar) by the following sequence of steps: (1) react DNA at 45°C for 2 h under aqueous conditions with CAX-B (has a benzyl bromide functional group to label active hydrogen sites) in the presence of triethylamine; (2) remove residual reagents by precipitating and washing the DNA (a convenient step); (3) digest the DNA enzymatically to nucleotides and remove unlabeled nucleotides by nonpolar solid-phase extraction (also a convenient step); and (4) detect CAX-labeled, adducted nucleotides by LC/MS2 or a matrix-assisted laser desorption/ionization (MALDI)-MS technique. RESULTS: Examples of the 42 DNA or RNA adducts detected, or tentatively so based on accurate mass and fragmentation data, are as follows: 8-oxo-dGMP, ethyl-dGMP, hydroxyethyl-dGMP (four isomers, all HPLC-resolved), uracil-glycol, apurinic/apyrimidinic sites, benzo[a]pyrene-dGMP, and, for the first time, benzoquinone-hydroxymethyl-dCMP. Importantly, these adducts are detected in a single procedure under a single set of conditions. Sensitivity, however, is only defined in a preliminary way, namely the latter adduct seems to be detected at a level of about 4 adducts in 109 nucleotides (S/N ~30). CONCLUSIONS: CAX-Prelabeling is an emerging new technique for DNA adductomics, providing polar DNA adductomics in a practical way for the first time. Further study of the method is encouraged to better characterize and extend its performance, especially in scope and sensitivity.


Asunto(s)
Aductos de ADN/análisis , Animales , Benzo(a)pireno/análisis , Compuestos de Bencilo , Cationes , Bovinos , Cromatografía Líquida de Alta Presión , Aductos de ADN/química , Aductos de ADN/metabolismo , Etilaminas , Guanina/análogos & derivados , Guanina/análisis , Humanos , Nucleótidos/metabolismo , Radioisótopos de Fósforo , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Uracilo/análogos & derivados , Uracilo/análisis
8.
Mikrochim Acta ; 188(2): 58, 2021 01 28.
Artículo en Inglés | MEDLINE | ID: mdl-33507409

RESUMEN

Oxidative DNA damage plays an important role in the pathogenesis of various diseases. Among oxidative DNA lesions, 8-oxoguanine (8-oxoG) and its corresponding nucleotide 8-oxo-2'-deoxyguanosine (8-oxodG), the guanine and deoxyguanosine oxidation products, have gained much attention, being considered biomarkers for oxidative DNA damage. Both 8-oxoG and 8-oxodG are used to predict overall body oxidative stress levels, to estimate the risk, to detect, and to make prognosis related to treatment of cancer, degenerative, and other age-related diseases. The need for rapid, easy, and low-cost detection and quantification of 8-oxoG and 8-oxodG biomarkers of oxidative DNA damage in complex samples, urine, blood, and tissue, caused an increasing interest on electrochemical sensors based on modified electrodes, due to their high sensitivity and selectivity, low-cost, and easy miniaturization and automation. This review aims to provide a comprehensive and exhaustive overview of the fundamental principles concerning the electrochemical determination of the biomarkers 8-oxoG and 8-oxodG using nanostructured materials (NsM), such as carbon nanotubes, carbon nanofibers, graphene-related materials, gold nanomaterials, metal nanoparticles, polymers, nanocomposites, dendrimers, antibodies and aptamers, and modified electrochemical sensors.


Asunto(s)
8-Hidroxi-2'-Desoxicoguanosina/análisis , Guanina/análogos & derivados , Nanoestructuras/química , Animales , Biomarcadores/análisis , Línea Celular Tumoral , Daño del ADN , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Electrodos , Guanina/análisis , Humanos , Estrés Oxidativo
9.
Cells ; 10(1)2021 01 03.
Artículo en Inglés | MEDLINE | ID: mdl-33401566

RESUMEN

Photosynthetic energy conversion and the resulting photoautotrophic growth of green algae can only occur in daylight, but DNA replication, nuclear and cellular divisions occur often during the night. With such a light/dark regime, an algal culture becomes synchronized. In this study, using synchronized cultures of the green alga Desmodesmus quadricauda, the dynamics of starch, lipid, polyphosphate, and guanine pools were investigated during the cell cycle by two independent methodologies; conventional biochemical analyzes of cell suspensions and confocal Raman microscopy of single algal cells. Raman microscopy reports not only on mean concentrations, but also on the distribution of pools within cells. This is more sensitive in detecting lipids than biochemical analysis, but both methods-as well as conventional fluorescence microscopy-were comparable in detecting polyphosphates. Discrepancies in the detection of starch by Raman microscopy are discussed. The power of Raman microscopy was proven to be particularly valuable in the detection of guanine, which was traceable by its unique vibrational signature. Guanine microcrystals occurred specifically at around the time of DNA replication and prior to nuclear division. Interestingly, guanine crystals co-localized with polyphosphates in the vicinity of nuclei around the time of nuclear division.


Asunto(s)
Ciclo Celular , Chlorophyta/citología , Guanina/análisis , Lípidos/análisis , Microscopía , Polifosfatos/análisis , Espectrometría Raman , Almidón/análisis , Tamaño de la Célula , Pared Celular/química , Chlorophyta/crecimiento & desarrollo , Gotas Lipídicas/metabolismo , Factores de Tiempo
10.
Bioelectrochemistry ; 138: 107721, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33360587

RESUMEN

In this paper, we present a computational study investigating the electronic properties of DNA nucleobases (Adenine, Guanine, Cytosine and Thymine) on χ3 borophene using a combination of density functional theory (DFT) and non-equilibrium Green's function (NEGF) formalism.The adsorption energy, equilibrium distance, net charge of transfer, and density of states (DOSs) are obtained at different molecule orientations and selective positions.The most stable geometries of DNA molecules on χ3 borophene are also determined.By using (NEGF) formalism, the electronic transmission and electrical current are calculated separately as a function of applied bias voltage for each nucleobase. We find that attaching this molecule to borophene changes the electrical conductivity.Results indicate the strong potential of borophene in adsorption of the DNA molecules, meaning this two-dimensional material could be a suitable candidate for future DNA sequencing devices.


Asunto(s)
Adenina/análisis , Boro/química , Citosina/análisis , Teoría Funcional de la Densidad , Guanina/análisis , Timina/análisis , Adenina/química , Adsorción , Citosina/química , Transporte de Electrón , Guanina/química , Modelos Moleculares , Conformación Molecular , Timina/química
11.
Molecules ; 25(17)2020 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-32825151

RESUMEN

Aquaculture represents a major part of the world's food supply. This area of food production is developing rapidly, and as such the tools and analytical techniques used to monitor and assess the quality of fish need to also develop and improve. The use of spatially off-set Raman spectroscopy (SORS) is particularly well-suited for these applications, given the ability of this technique to take subsurface measurements as well as being rapid, non-destructive and label-free compared to classical chemical analysis techniques. To explore this technique for analysing fish, SORS measurements were taken on commercially significant whole fish through the skin in different locations. The resulting spectra were of high quality with subsurface components such as lipids, carotenoids, proteins and guanine from iridophore cells clearly visible in the spectra. These spectral features were characterised and major bands identified. Chemometric analysis additionally showed that clear differences are present in spectra not only from different sections of a fish but also between different species. These results highlight the potential application for SORS analysis for rapid quality assessment and species identification in the aquaculture industry by taking through-skin measurements.


Asunto(s)
Biomarcadores/análisis , Peces/metabolismo , Contaminación de Alimentos/análisis , Melanóforos/metabolismo , Piel/química , Espectrometría Raman/métodos , Animales , Carotenoides/análisis , Guanina/análisis , Lípidos/análisis , Proteínas/análisis
12.
Nature ; 584(7820): 279-285, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32760005

RESUMEN

In pathophysiology, reactive oxygen species oxidize biomolecules that contribute to disease phenotypes1. One such modification, 8-oxoguanine2 (o8G), is abundant in RNA3 but its epitranscriptional role has not been investigated for microRNAs (miRNAs). Here we specifically sequence oxidized miRNAs in a rat model of the redox-associated condition cardiac hypertrophy4. We find that position-specific o8G modifications are generated in seed regions (positions 2-8) of selective miRNAs, and function to regulate other mRNAs through o8G•A base pairing. o8G is induced predominantly at position 7 of miR-1 (7o8G-miR-1) by treatment with an adrenergic agonist. Introducing 7o8G-miR-1 or 7U-miR-1 (in which G at position 7 is substituted with U) alone is sufficient to cause cardiac hypertrophy in mice, and the mRNA targets of o8G-miR-1 function in affected phenotypes; the specific inhibition of 7o8G-miR-1 in mouse cardiomyocytes was found to attenuate cardiac hypertrophy. o8G-miR-1 is also implicated in patients with cardiomyopathy. Our findings show that the position-specific oxidation of miRNAs could serve as an epitranscriptional mechanism to coordinate pathophysiological redox-mediated gene expression.


Asunto(s)
Cardiomegalia/genética , Cardiomegalia/patología , Silenciador del Gen , MicroARNs/química , MicroARNs/metabolismo , Animales , Emparejamiento Base , Línea Celular , Modelos Animales de Enfermedad , Guanina/análogos & derivados , Guanina/análisis , Guanina/química , Guanina/metabolismo , Humanos , Ratones , MicroARNs/genética , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Oxidación-Reducción , Ratas , Transcripción Genética/genética , Transcriptoma/genética
13.
Int J Mol Sci ; 21(14)2020 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-32679695

RESUMEN

DNA damage plays a decisive role in epigenetic effects. The detection and analysis of DNA damages, like the most common change of guanine (G) to 8-oxo-7,8-dihydroguanine (OG), is a key factor in cancer research. It is especially true for G quadruplex structure (GQ), which is one of the best-known examples of a non-canonical DNA arrangement. In the present work, we provided an overview on analytical methods in connection with the detection of OG in oligonucleotides with GQ-forming capacity. Focusing on the last five years, novel electrochemical tools, like dedicated electrodes, were overviewed, as well as different optical methods (fluorometric assays, resonance light scattering or UV radiation) along with hyphenated detection and structural analysis methods (CD, NMR, melting temperature analysis and nanopore detection) were also applied for OG detection. Additionally, GQ-related computational simulations were also summarized. All these results emphasize that OG detection and the analysis of the effect of its presence in higher ordered structures like GQ is still a state-of-the-art research line with continuously increasing interest.


Asunto(s)
Daño del ADN , Guanina/metabolismo , Oligonucleótidos/metabolismo , Estrés Oxidativo , Animales , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Dicroismo Circular/instrumentación , Dicroismo Circular/métodos , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Fluorometría/instrumentación , Fluorometría/métodos , G-Cuádruplex , Guanina/análisis , Humanos , Luz , Mediciones Luminiscentes/instrumentación , Mediciones Luminiscentes/métodos , Espectroscopía de Resonancia Magnética/instrumentación , Espectroscopía de Resonancia Magnética/métodos , Espectrometría de Masas/instrumentación , Espectrometría de Masas/métodos , Oligonucleótidos/química , Dispersión de Radiación
14.
J Am Chem Soc ; 142(31): 13283-13287, 2020 08 05.
Artículo en Inglés | MEDLINE | ID: mdl-32664726

RESUMEN

MutY glycosylase excises adenines misincorporated opposite the oxidatively damaged lesion, 8-oxo-7,8-dihydroguanine (OG), to initiate base excision repair and prevent G to T transversion mutations. Successful repair requires MutY recognition of the OG:A mispair amidst highly abundant and structurally similar undamaged DNA base pairs. Herein we use a combination of in vitro and bacterial cell repair assays with single-molecule fluorescence microscopy to demonstrate that both a C-terminal domain histidine residue and the 2-amino group of OG base are critical for MutY detection of OG:A sites. These studies are the first to directly link deficiencies in MutY lesion detection with incomplete cellular repair. These results suggest that defects in lesion detection of human MutY (MUTYH) variants may prove predictive of early-onset colorectal cancer known an MUTYH-associated polyposis. Furthermore, unveiling these specific molecular determinants for repair makes it possible to envision new MUTYH-specific cancer therapies.


Asunto(s)
ADN Glicosilasas/metabolismo , Guanina/análogos & derivados , Histidina/metabolismo , ADN Glicosilasas/química , Guanina/análisis , Guanina/metabolismo , Humanos , Microscopía Fluorescente , Modelos Moleculares
15.
Science ; 368(6498): 1465-1468, 2020 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-32587016

RESUMEN

DNA and proteins are chiral: Their three-dimensional structures cannot be superimposed with their mirror images. Circular dichroism spectroscopy is widely used to characterize chiral compounds, but data interpretation is difficult in the case of mixtures. We recorded the electronic circular dichroism spectra of DNA helices separated in a mass spectrometer. We studied guanine-rich strands having various secondary structures, electrosprayed them as negative ions, irradiated them with an ultraviolet nanosecond optical parametric oscillator laser, and measured the difference in electron photodetachment efficiency between left and right circularly polarized light. The reconstructed circular dichroism ion spectra resembled those of their solution-phase counterparts, thereby allowing us to assign the DNA helical topology. The ability to measure circular dichroism directly on biomolecular ions expands the capabilities of mass spectrometry for structural analysis.


Asunto(s)
Dicroismo Circular/métodos , ADN/química , Guanina/química , Espectrometría de Masas/métodos , Guanina/análisis , Conformación de Ácido Nucleico
16.
Biochemistry ; 59(28): 2627-2639, 2020 07 21.
Artículo en Inglés | MEDLINE | ID: mdl-32578995

RESUMEN

Telomeres are hot spots for mutagenic oxidative and methylation base damage due to their high guanine content. We used single-molecule fluorescence resonance energy transfer detection and biochemical assays to determine how different positions and types of guanine damage and mutations alter telomeric G-quadruplex structure and telomerase activity. We compared 15 modifications, including 8-oxoguanine (8oxoG), O-6-methylguanine (O6mG), and all three possible point mutations (G to A, T, and C) at the 3' three terminal guanine positions of a telomeric G-quadruplex, which is the critical access point for telomerase. We found that G-quadruplex structural instability was induced in the order C < T < A ≤ 8oxoG < O6mG, with the perturbation caused by O6mG far exceeding the perturbation caused by other base alterations. For all base modifications, the central G position was the most destabilizing among the three terminal guanines. While the structural disruption by 8oxoG and O6mG led to concomitant increases in telomerase binding and extension activity, the structural perturbation by point mutations (A, T, and C) did not, due to disrupted annealing between the telomeric overhang and the telomerase RNA template. Repositioning the same mutations away from the terminal guanines caused both G-quadruplex structural instability and elevated telomerase activity. Our findings demonstrate how a single-base modification drives structural alterations and telomere lengthening in a position-dependent manner. Furthermore, our results suggest a long-term and inheritable effect of telomeric DNA damage that can lead to telomere lengthening, which potentially contributes to oncogenesis.


Asunto(s)
G-Cuádruplex , Guanina/análisis , ARN/metabolismo , Telomerasa/metabolismo , Telómero/genética , Daño del ADN , Guanina/análogos & derivados , Guanina/metabolismo , Células HEK293 , Humanos , Mutación Puntual , Complejo Shelterina , Telómero/química , Telómero/metabolismo , Proteínas de Unión a Telómeros/metabolismo
17.
Chem Res Toxicol ; 33(7): 1609-1622, 2020 07 20.
Artículo en Inglés | MEDLINE | ID: mdl-32529823

RESUMEN

Acrylonitrile (ACN), which is a widely used industrial chemical, induces cancers in multiple organs/tissues of rats by unresolved mechanisms. For this report, evidence for ACN-induced direct/indirect DNA damage and mutagenesis was investigated by assessing the ability of ACN, or its reactive metabolite, 2-cyanoethylene oxide (CEO), to bind to DNA in vitro, to form select DNA adducts [N7-(2'-oxoethyl)guanine, N2,3-ethenoguanine, 1,N6-ethenodeoxyadenosine, and 3,N4-ethenodeoxycytidine] in vitro and/or in vivo, and to perturb the frequency and spectra of mutations in the hypoxanthine-guanine phosphoribosyltransferase (Hprt) gene in rats exposed to ACN in drinking water. Adducts and frequencies and spectra of Hprt mutations were analyzed using published methods. Treatment of DNA from human TK6 lymphoblastoid cells with [2,3-14C]-CEO produced dose-dependent binding of 14C-CEO equivalents, and treatment of DNA from control rat brain/liver with CEO induced dose-related formation of N7-(2'-oxoethyl)guanine. No etheno-DNA adducts were detected in target tissues (brain and forestomach) or nontarget tissues (liver and spleen) in rats exposed to 0, 3, 10, 33, 100, or 300 ppm ACN for up to 105 days or to 0 or 500 ppm ACN for ∼15 months; whereas N7-(2'-oxoethyl)guanine was consistently measured at nonsignificant concentrations near the assay detection limit only in liver of animals exposed to 300 or 500 ppm ACN for ≥2 weeks. Significant dose-related increases in Hprt mutant frequencies occurred in T-lymphocytes from spleens of rats exposed to 33-500 ppm ACN for 4 weeks. Comparisons of "mutagenic potency estimates" for control rats versus rats exposed to 500 ppm ACN for 4 weeks to analogous data from rats/mice treated at a similar age with N-ethyl-N-nitrosourea or 1,3-butadiene suggest that ACN has relatively limited mutagenic effects in rats. Considerable overlap between the sites and types of mutations in ACN-exposed rats and butadiene-exposed rats/mice, but not controls, provides evidence that the carcinogenicity of these epoxide-forming chemicals involves corresponding mutagenic mechanisms.


Asunto(s)
Acrilonitrilo/toxicidad , Carcinógenos/toxicidad , Aductos de ADN/análisis , Guanina/análisis , Hipoxantina Fosforribosiltransferasa/genética , Acrilonitrilo/administración & dosificación , Acrilonitrilo/metabolismo , Administración Oral , Animales , Carcinógenos/administración & dosificación , Carcinógenos/metabolismo , Células Cultivadas , Aductos de ADN/biosíntesis , Relación Dosis-Respuesta a Droga , Óxido de Etileno/administración & dosificación , Óxido de Etileno/análogos & derivados , Óxido de Etileno/metabolismo , Óxido de Etileno/toxicidad , Femenino , Guanina/análogos & derivados , Guanina/biosíntesis , Humanos , Hipoxantina Fosforribosiltransferasa/metabolismo , Masculino , Ratones , Ratas , Ratas Endogámicas F344
18.
Chem Commun (Camb) ; 56(48): 6535-6538, 2020 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-32395729

RESUMEN

A new chemiluminescence aptasensor for sensitive and efficient detection of 8-hydroxyguanine based on the synergistic interaction of Ni NPs@l-histidine@aptamer@MBs has been developed, and it has been applied in the real urine samples of cancer patients.


Asunto(s)
Guanina/análogos & derivados , Histidina/química , Mediciones Luminiscentes/métodos , Nanopartículas del Metal/química , Níquel/química , Aptámeros de Nucleótidos/química , Guanina/análisis , Guanina/orina , Humanos , Magnetismo , Neoplasias/diagnóstico
19.
Phys Chem Chem Phys ; 22(20): 11452-11459, 2020 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-32391530

RESUMEN

Detection and sequencing of various nucleobases are of immense usefulness that can revolutionise future medical diagnostics procedures. In this regard, the newly discovered 2D material, C3N, has demonstrated supreme potential for future nanoelectronic and spintronic developments due to its unique sets of electronic properties and structural similarity to graphene. Herein, we have investigated the effect of various nucleobases in the close vicinity of a C3N nanoribbon. Our extensive calculations revealed significant changes in the transport behaviour in the presence of DNA/RNA molecules. The transport response can be further modified through the (i) incorporation of doping, (ii) presence of defects, (iii) concentration of the adsorbed molecule, etc. Furthermore, in the presence of a gate voltage in a field-effect transistor (FET) geometry, the conductivity response can be improved significantly with an ∼100% change in the presence of an adsorbed molecule. The observation of a negative differential resistance (NDR) in the C3N system has also been reported here for the first time. Our current observation demonstrates the usefulness of the C3N system as a next generation bio-sensor for the sequencing of various nucleobases, offering new leads for future developments in bioelectronics, superior sensing architectures and sustainable designs.


Asunto(s)
Nanotubos de Carbono/química , Nitrilos/química , Adenina/análisis , Adenina/química , Adsorción , Técnicas Biosensibles/métodos , Citosina/análisis , Citosina/química , Teoría Funcional de la Densidad , Guanina/análisis , Guanina/química , Modelos Químicos , Timina/análisis , Timina/química , Uracilo/análisis , Uracilo/química
20.
Nucleic Acids Res ; 48(11): 5907-5925, 2020 06 19.
Artículo en Inglés | MEDLINE | ID: mdl-32383760

RESUMEN

Mammalian antibody switch regions (∼1500 bp) are composed of a series of closely neighboring G4-capable sequences. Whereas numerous structural and genome-wide analyses of roles for minimal G4s in transcriptional regulation have been reported, Long G4-capable regions (LG4s)-like those at antibody switch regions-remain virtually unexplored. Using a novel computational approach we have identified 301 LG4s in the human genome and find LG4s prone to mutation and significantly associated with chromosomal rearrangements in malignancy. Strikingly, 217 LG4s overlap annotated enhancers, and we find the promoters regulated by these enhancers markedly enriched in G4-capable sequences suggesting G4s facilitate promoter-enhancer interactions. Finally, and much to our surprise, we also find single-stranded loops of minimal G4s within individual LG4 loci are frequently highly complementary to one another with 178 LG4 loci averaging >35 internal loop:loop complements of >8 bp. As such, we hypothesized (then experimentally confirmed) that G4 loops within individual LG4 loci directly basepair with one another (similar to characterized stem-loop kissing interactions) forming a hitherto undescribed, higher-order, G4-based secondary structure we term a 'G4 Kiss or G4K'. In conclusion, LG4s adopt novel, higher-order, composite G4 structures directly contributing to the inherent instability, regulatory capacity, and maintenance of these conspicuous genomic regions.


Asunto(s)
Elementos de Facilitación Genéticos , Genoma Humano , Guanina , Conformación de Ácido Nucleico , Emparejamiento Base , G-Cuádruplex , Reordenamiento Génico , Variación Genética , Genómica , Guanina/análisis , Humanos , Saccharomyces cerevisiae/genética , Duplicaciones Segmentarias en el Genoma , Eliminación de Secuencia
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