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1.
Molecules ; 27(7)2022 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-35408551

RESUMO

Inspired by the recent cocrystallization and theory of energetic materials, we theoretically investigated the intermolecular vibrational energy transfer process and the non-covalent intermolecular interactions between explosive compounds. The intermolecular interactions between 2,4,6-trinitrotoluene (TNT) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and between 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) and CL-20 were studied using calculated two-dimensional infrared (2D IR) spectra and the independent gradient model based on the Hirshfeld partition (IGMH) method, respectively. Based on the comparison of the theoretical infrared spectra and optimized geometries with experimental results, the theoretical models can effectively reproduce the experimental geometries. By analyzing cross-peaks in the 2D IR spectra of TNT/CL-20, the intermolecular vibrational energy transfer process between TNT and CL-20 was calculated, and the conclusion was made that the vibrational energy transfer process between CL-20 and TNTII (TNTIII) is relatively slower than between CL-20 and TNTI. As the vibration energy transfer is the bridge of the intermolecular interactions, the weak intermolecular interactions were visualized using the IGMH method, and the results demonstrate that the intermolecular non-covalent interactions of TNT/CL-20 include van der Waals (vdW) interactions and hydrogen bonds, while the intermolecular non-covalent interactions of HMX/CL-20 are mainly comprised of vdW interactions. Further, we determined that the intermolecular interaction can stabilize the trigger bond in TNT/CL-20 and HMX/CL-20 based on Mayer bond order density, and stronger intermolecular interactions generally indicate lower impact sensitivity of energetic materials. We believe that the results obtained in this work are important for a better understanding of the cocrystal mechanism and its application in the field of energetic materials.


Assuntos
Substâncias Explosivas , Trinitrotolueno , Transferência de Energia , Substâncias Explosivas/química , Ligação de Hidrogênio , Trinitrotolueno/química , Vibração
2.
Inorg Chem ; 59(23): 16924-16935, 2020 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-33170004

RESUMO

By utilizing the 2-hydroxyisophthalic acid (H3ipO) ligand, 2D metal-organic frameworks (MOFs) featuring rare Ophenol-bridged [Ln2]-magnetic building blocks (MBBs), [Ln2(ipO)2(DMF)(H2O)] [Ln = Gd (1), Dy (2); DMF = N,N-dimethylformamide], were rationally designed and synthesized. When the reaction solvents that behave as terminal ligands were changed, the coordination geometries of LnIII ions and the arrangement fashion of [Ln2]-MBBs for these MOFs were modified accordingly. Another type of 2D MOF of [Ln2(ipO)2(H2O)4]·2H2O [Ln = Gd (3), Dy (4)] was thus obtained. MOFs 1 and 3 exhibited favorable magnetocaloric effect, whose maximum -ΔSm values reach 30.0 and 31.7 J kg-1 K-1, respectively. None of the single-molecule-magnet (SMM) behavior was observed in 2. However, from 2 to 4, the change of the terminal coordinated solvents brought obvious improvement of the magnetic properties. MOF 4 showed interesting relaxation behavior, in which dual relaxation was only visible under weak direct-current fields, and its highest effective energy barrier (Ueff) reached up to 243 K. Ab initio calculations revealed the tuning mechanism of the terminal coordinated solvents. Their change optimized the arrangements of the magnetic axis of the DyIII centers in both each MBB and the whole framework, thus improving the magnetic anisotropy and magnetic interactions of the system. Significantly, within the [Dy2]-MBBs of 4, the angle made by the individual magnetic axis and Dy···Dy' line is nearly 0°. This case favoring a high SMM performance not only was scarcely achieved in discrete {Ln2}-SMMs with numerous members but also has never been observed in any MBB-based MOFs as far as we know.

3.
Dalton Trans ; 49(44): 15739-15749, 2020 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-33146181

RESUMO

The novel multidentate chelating ligands N'-(2-pyridylmethylidene)-2-(2-pyridylmethylideneamino)benzohydrazide (Hpphz) and N'-(2-salicylmethylidene)-2-(2-salicylmethylideneamino)benzohydrazide (H3sshz), which incorporate both amine and acylhydrazine Schiff base groups, were synthesized and investigated in DyIII coordination chemistry. The reactions of Hpphz and Dy(OAc)3·4H2O have yielded two {Dy2} featuring double OAc- bridges: [Dy2(H2aphz)2(OAc)4(ROH)2] [R = Me (1) and Et (2)], where the Hpphz ligands were in situ hydrolyzed into 2-amino-(2-pyridylmethylideneamino)benzohydrazide ions (H2aphz-). Besides, the reaction between H3sshz and Dy(NO)3·6H2O afforded a [Dy6(sshz)4(µ3-OH)4(µ4-O)(MeOH)4]2·17.5MeOH·2H2O cluster (3). This cluster contained two discrete {Dy6} cores, each of which consisted of a pair of {Dy3} triangular units. All the complexes displayed a single relaxation process of single-molecule magnet (SMM) behaviors under a zero dc field. Both 1 and 2 showed field-induced dual magnetic-relaxation behaviors. However, their diluted samples (1@Y and 2@Y) only showed one-step relaxation behaviors whether under a zero or applied dc field, indicating that the dual magnetic-relaxation behaviors of 1 and 2 were absent after the dilution. Combined with ab initio calculations, it could be infered that the dual magnetic-relaxation behaviors of 1 and 2 might be ascribled to the joint contributions of the single ion anisotropy and magnetic interactions. Examples of this type are rather rare in previous studies. Ab initio calculations also suggested that the discrepancy between the relaxation processes of 1 and 2 may be caused by the small difference between their magnetic interactions.

4.
Yi Chuan ; 42(6): 599-612, 2020 Jun 20.
Artigo em Chinês | MEDLINE | ID: mdl-32694118

RESUMO

Colorectal cancer (CRC) is a malignant cancer with high incidence and mortality in the world. Immunotherapy targeting neoantigens can induce durable tumor regression in cancer patients, but is almost limited to personalized precision therapy, due to the individual differences of unique neoantigens. With the discovery of many common oncogenic mutations, and such mutation-associated neoantigens could cover more patients, and hence are valuable in clinical field. However, whether the common neoantigens can be identified in CRC is unknown. Combining the somatic mutations data from 321 CRC patients with a filter standard and 7 predicted algorithms, we screened and obtained 25 HLA-A*1101-restricted common neoantigens with a high binding affinity (IC50<50 nmol/L) and presentation score (>0.90). Besides the positive epitope KRAS_G12V8-16, 11 out of 25 common neoantigens specifically induced in vitro pre- stimulated cytotoxic lymphocyte (CTL) to secrete interferon gamma (IFN-γ). Moreover, combining cell-sorting technology and single-cell RNA sequencing, the immune repertoire profiles of C1orf170_S418G413-421 and KRAS_G12V8-16-specific CTL were analyzed and validated. Their related T-cell receptor engineered T cell (TCR-T) cells could also recognize the neoantigens and secrete IFN-γ. Hence, we have established a method to screen for common neoantigens with immunogenicity in CRC based on the public somatic mutation library. It can provide essential peptide and TCR information for immunotherapies, such as peptides, dendritic cells (DC) vaccines, TCR-like antibodies, TCR-T, etc., for the CRC and other cancers, which has practical application value in the clinics.


Assuntos
Antígenos de Neoplasias , Neoplasias Colorretais , Antígenos de Neoplasias/genética , Neoplasias Colorretais/genética , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/terapia , Detecção Precoce de Câncer , Humanos , Mutação , Receptores de Antígenos de Linfócitos T/genética
5.
J Int Med Res ; 48(4): 300060519894790, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31884845

RESUMO

OBJECTIVE: To examine the clinical effect of computed tomography angiography (CTA) on parameters of intracranial aneurysms in different locations and with different sizes using digital subtraction angiography (DSA) as the standard. METHODS: Patients with intracranial aneurysms who underwent CTA examinations at the same center and received DSA examinations within 3 days were analyzed retrospectively. The morphological parameters of the aneurysms and parent arteries were measured with these two methods. RESULTS: Mean aneurysm size and parent artery diameter were not different between CTA and DSA. The size of microaneurysms was significantly smaller with DSA than with CTA. The aneurysmal neck width was not different between CTA and DSA. DSA could clearly evaluate the relationship between the aneurysmal neck and the parent artery in all cases. However, CTA had a 90% accuracy rate of visualizing this relationship. CONCLUSION: The accuracy rates of evaluating aneurysm size and the aneurysmal neck width and parent artery diameter are similar between CTA and DSA. A DSA examination is essential for evaluating the relationship among microaneurysms, the aneurysmal neck, and the parent artery. CTA is widely applied and more safe in clinical practice, while DSA has a better guiding effect than CTA for some complicated aneurysms.


Assuntos
Aneurisma Intracraniano , Angiografia Digital , Angiografia Cerebral , Angiografia por Tomografia Computadorizada , Humanos , Aneurisma Intracraniano/diagnóstico por imagem , Estudos Retrospectivos , Sensibilidade e Especificidade
6.
Yi Chuan ; 41(11): 1041-1049, 2019 Nov 20.
Artigo em Chinês | MEDLINE | ID: mdl-31735706

RESUMO

Accurate epitope presentation prediction is a key procedure in tumour immunotherapies based on neoantigen for targeting T cell specific epitopes. Epitopes identified by mass spectrometry (MS) is valuable to train an epitope presentation prediction model. In spite of the accelerating accumulation of MS data, the number of epitopes that match most of human leukocyte antigens (HLAs) is relatively small, which makes it difficult to build a reliable prediction model. Therefore, this research attempted to use the transfer learning method to train a model to learn common features among the mixed allele specific epitopes. Then based on this pre-trained model, we used the allele-specific epitopes to train the final epitope presentation prediction model, termed Pluto. The average 0.1% positive predictive value (PPV) of Pluto outperformed the prediction model without pretraining with a margin of 0.078 on the same validation dataset. When evaluating Pluto on external HLA eluted ligand datasets, Pluto achieved an averaged 0.1% PPV of 0.4255, which is better than the prediction model without pretraining (0.3824) and other popular methods, including MixMHCpred (0.3369), NetMHCpan4.0-EL (0.4000), NetMHCpan4.0-BA (0.3188) and MHCflurry (0.3002). Moreover, when it comes to the evaluation of predicting immunogenicity, Pluto can identify more neoantigens than other tools. Pluto is publicly available at https://github.com/weipenegHU/Pluto.


Assuntos
Algoritmos , Apresentação de Antígeno , Epitopos de Linfócito T/química , Animais , Humanos , Ligantes , Aprendizado de Máquina
7.
Inorganica Chim Acta ; 489: 85-92, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-34079145

RESUMO

Four mononuclear lanthanide complexes containing 4'-phenyl-2,2':6',2″-terpyridine (ptpy), [Ln(NO3)3(ptpy) (H2O)] (Ln = Eu (1), Gd (2), Tb (3), Dy (4)), were solvothermally synthesized and characterized via elemental analysis, infrared spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction, and powder X-ray diffraction. Hirshfeld surfaces and the solid-state luminescence properties of the complexes were investigated. The 3-D Hirshfeld surface and 2-D fingerprint plots show that the main interactions are the O H/H O intermolecular interactions in 1-4. Solid-state luminescence investigation reveals that GdIII complex 2 displays a ligand-centered emission and the EuIII, TbIII and DyIII complexes 1, 3 and 4 show the characteristic lanthanide-centered luminescence upon UV excitations. The EuIII and TbIII complexes exhibit red (CIE: 0.6549, 0.3447) and green (CIE: 0.3760, 0.5412) luminescence in the solid state with quantum yields of 16.8% and 0.8% and lifetimes of 0.545 and 0.043 ms, respectively. Density functional theory (DFT) calculations were conducted to unravel the HOMO-LUMO energy gaps of the structures of ptpy and complexes 1 and 3.

8.
Cell Rep ; 25(13): 3800-3810.e6, 2018 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-30590050

RESUMO

Glucose-stimulated insulin secretion from islet ß cells is mediated by KATP channels. However, the role of non-KATP K+ channels in insulin secretion is largely unknown. Here, we show that a non-KATP K+ channel, KCNH6, plays a key role in insulin secretion and glucose hemostasis in humans and mice. KCNH6 p.P235L heterozygous mutation co-separated with diabetes in a four-generation pedigree. Kcnh6 knockout (KO) or Kcnh6 p.P235L knockin (KI) mice had a phenotype characterized by changing from hypoglycemia with hyperinsulinemia to hyperglycemia with insulin deficiency. Islets from the young KO mice had increased intracellular calcium concentration and increased insulin secretion. However, islets from the adult KO mice not only had increased intracellular calcium levels but also had remarkable ER stress and apoptosis, associated with loss of ß cell mass and decreased insulin secretion. Therefore, dysfunction of KCNH6 causes overstimulation of insulin secretion in the short term and ß cell failure in the long term.


Assuntos
Diabetes Mellitus/patologia , Canais de Potássio Éter-A-Go-Go/metabolismo , Hiperinsulinismo/patologia , Secreção de Insulina , Potenciais de Ação , Adolescente , Adulto , Animais , Sequência de Bases , Diabetes Mellitus/genética , Canais de Potássio Éter-A-Go-Go/genética , Feminino , Genes Dominantes , Células HEK293 , Humanos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Ativação do Canal Iônico , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação/genética , Linhagem , Adulto Jovem
9.
Mater Sci Eng C Mater Biol Appl ; 92: 657-662, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30184792

RESUMO

Assembly of anisotropic nanoparticles which need well controlling of assembly direction and spatial arrangement is more interesting than one-dimensional nanoparticles assemblies. As confirmed by observing of transmission electron microscopy images and analysis of plasmon resonance spectrum transformations, we found that silver triangular nanoplates (TNPs) without further modification could be face-to-face assembled by citrate. The face-to-face assembly of silver TNPs could be disassembled quickly by heating at a wide temperature range from 30 to 80 °C. In this process, an obvious localized surface plasmon resonance (LSPR) peak shift and a color change of solution from pink to purple could be observed. Moreover, the disassembled silver TNPs suspension is very stable that no significant peak shift of silver TNPs spectrum was observed in 8 h after removing of silver TNPs from a hearing area. Therefore, we fabricated an irreversible temperature indicator by measuring the relationship between the shift of LSPR peak and heating temperature, and by watching the color change of the solution in a certain environment. The irreversible temperature indicator has potential to develop a temperature label for revealing temperature history of a thermosensitive product which cannot expose to excessive temperature.


Assuntos
Ácido Cítrico/química , Nanopartículas Metálicas/química , Prata/química , Ressonância de Plasmônio de Superfície , Nanopartículas Metálicas/ultraestrutura , Tamanho da Partícula
10.
Phys Chem Chem Phys ; 20(25): 17253-17261, 2018 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-29901061

RESUMO

Employing molecular dynamic (MD) simulations and solid-state density functional theory (DFT), we carried out thorough studies to understand the interaction-structure-property interrelationship of the co-crystal explosive 1 : 1 CL-20 : TNT. Our results revealed that the co-crystallization of CL-20 and TNT molecules enhances the intermolecular binding forces, where the main driving force for the formation of the co-crystal CL-20/TNT comes from HO and CO interactions, while OO contributes to the co-crystal stabilization. Furthermore, we also used the concept of atoms in molecule (AIM) and the reduced density gradient (RDG) to describe the spatial arrangements and interactions of co-crystal compositions, which showed that although the adjoining TNT molecules possess two symmetry groups and the adjoining CL-20 molecules possess the same symmetry group, their interactions are not identical. These spatial arrangements provide a good reference to the formation of other co-crystals. When the obtained structural and detonation properties of the three crystals were compared, it was observed that the CL-20/TNT co-crystal achieved the desirable properties of explosives, i.e., low-sensitivity and high-energy, possessing the advantages of both CL-20 and TNT explosives.

11.
Proc Natl Acad Sci U S A ; 115(16): 4218-4222, 2018 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-29610342

RESUMO

Reactive oxygen species formed within the mammalian cell can produce 8-oxo-7,8-dihydroguanine (8-oxoG) in mRNA, which can cause base mispairing during gene expression. Here we found that administration of 8-oxoGTP in MTH1-knockdown cells results in increased 8-oxoG content in mRNA. Under this condition, an amber mutation of the reporter luciferase is suppressed. Using second-generation sequencing techniques, we found that U-to-G changes at preassigned sites of the luciferase transcript increased when 8-oxoGTP was supplied. In addition, an increased level of 8-oxoG content in RNA induced the accumulation of aggregable amyloid ß peptides in cells expressing amyloid precursor protein. Our findings indicate that 8-oxoG accumulation in mRNA can alter protein synthesis in mammalian cells. Further work is required to assess the significance of these findings under normal physiological conditions.


Assuntos
Guanina/análogos & derivados , Mutagênese/genética , Biossíntese de Proteínas/genética , Transcrição Gênica/genética , Peptídeos beta-Amiloides/genética , Anticódon/genética , Pareamento de Bases , Códon sem Sentido , Enzimas Reparadoras do DNA/antagonistas & inibidores , Enzimas Reparadoras do DNA/genética , Técnicas de Silenciamento de Genes , Genes Reporter , Guanina/química , Células HeLa , Humanos , Luciferases/genética , Monoéster Fosfórico Hidrolases/antagonistas & inibidores , Monoéster Fosfórico Hidrolases/genética , Interferência de RNA , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Espécies Reativas de Oxigênio
12.
Dalton Trans ; 47(7): 2337-2343, 2018 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-29369317

RESUMO

A family of novel Ln nanoclusters, namely, [Ln11(ovpho)4(µ-CH3O)2(µ-H2O)2(µ3-OH)6(CH3OH)4(H2O)2(NO3)8](OH)·xH2O·yCH3OH [Ln = Gd (1), x = 1, y = 3; Ln = Tb (2), x = 1, y = 3; Ln = Dy (3), x = 0, y = 3], was obtained via solvothermal reactions of Ln(NO3)3 with a diacylhydrazone ligand N,N'-bis(o-vanillidene)pyridine-2,6-dicarbohydrazide N-oxide (H4ovpho). Their isostructural molecular structures are composed of two crystallographically symmetric {Ln6} rings sharing a Ln3+ ion, and display an unprecedented "double boat conformation" topology that, to our knowledge, has not yet been reported. Ophenol, Oenol and Ooxynitride from ovpho4- ligands, as well as Omethanol, Owater and Ohydroxyl help to bridge the Ln3+ ions. The structural variation between these {Ln11} clusters and a previously reported {Gd18} nanowheel, both of which are assembled by H4ovpho under the same synthetic method and reaction conditions, is caused only by changing the anions of Ln salts. Magnetic investigations revealed a large magnetocaloric effect (MCE) of 1, whose maximum -ΔSm value reaches 30.1 J kg-1 K-1 for ΔH = 50 kOe at 2.0 K. Additionally, it was found that 3 shows single-molecule magnets (SMMs) behavior, with an approximated energy barrier Ueff = 6.13 K and pre-exponential factor τ0 = 1.70 × 10-6 s.

13.
Mol Neurobiol ; 54(3): 1919-1926, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-26899574

RESUMO

The objective of this study was to investigate the association between serum resistin levels and acute cerebral infarction (ACI). PubMed, SpringerLink, Wiley, EBSCO, Ovid, Web of Science, Wanfang, China National Knowledge Infrastructure, and VIP databases (last updated search in October 2014) were exhaustively searched, and data from the eligible studies were extracted and analyzed to assess the association between serum resistin levels and ACI. STATA software (version 12.0, Stata Corporation, College Station, TX, USA) was utilized for data analysis. Ten studies including 1829 ACI patients and 1557 healthy controls were eligible for inclusion in the meta-analysis. Our major result revealed that ACI patients exhibited higher serum resistin levels compared with healthy controls. Asubgroup analysis based on ethnicity showed a significant association between serum resistin levels and ACI in Asians, but surprisingly not in Caucasians. The results of our meta-analysis suggest that serum resistin levels are associated with an increased risk of ACI.


Assuntos
Infarto Cerebral/sangue , Infarto Cerebral/diagnóstico , Resistina/sangue , Doença Aguda , Povo Asiático/etnologia , Biomarcadores/sangue , Estudos de Casos e Controles , Infarto Cerebral/etnologia , Humanos , Fatores de Risco , População Branca/etnologia
15.
Nat Commun ; 7: 12992, 2016 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-27703150

RESUMO

Hepatitis B virus (HBV) can integrate into the human genome, contributing to genomic instability and hepatocarcinogenesis. Here by conducting high-throughput viral integration detection and RNA sequencing, we identify 4,225 HBV integration events in tumour and adjacent non-tumour samples from 426 patients with HCC. We show that HBV is prone to integrate into rare fragile sites and functional genomic regions including CpG islands. We observe a distinct pattern in the preferential sites of HBV integration between tumour and non-tumour tissues. HBV insertional sites are significantly enriched in the proximity of telomeres in tumours. Recurrent HBV target genes are identified with few that overlap. The overall HBV integration frequency is much higher in tumour genomes of males than in females, with a significant enrichment of integration into chromosome 17. Furthermore, a cirrhosis-dependent HBV integration pattern is observed, affecting distinct targeted genes. Our data suggest that HBV integration has a high potential to drive oncogenic transformation.


Assuntos
Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/virologia , Vírus da Hepatite B/fisiologia , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/virologia , Transformação Celular Neoplásica , Ilhas de CpG , DNA Viral/genética , Feminino , Genoma Humano , Genoma Viral , Hepatite B Crônica/genética , Humanos , Estimativa de Kaplan-Meier , Cirrose Hepática/genética , Cirrose Hepática/virologia , Masculino , Reação em Cadeia da Polimerase em Tempo Real , Análise de Sequência de DNA , Análise de Sequência de RNA , Integração Viral
16.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(4): 951-5, 2015 Apr.
Artigo em Japonês | MEDLINE | ID: mdl-26197581

RESUMO

In the present paper, the authors studied fluorescence resonance energy transfer (FRET) phenomenon between silver triangular nanoplates and bovine serum albumin (BSA)/Rhodamine 6G fluorescence complex, and established a fluorescence method for the detection of cobalt ions. We found that when increasing the silver triangular nanoplates added to certain concentrations of fluorescent bovine serum albumin (BSA)/Rhodamine 6G complex, the fluorescence of Rhodamine 6G would be quenched up to 80% due to the FRET between the quencher and donor. However, in the presence of cobalt ions, the disassociation of the fluorescent complex from silver triangular nanoplates occurred and the fluorescence of the Rhodamine 6G recovered. The recovery of fluorescence intensity rate (I/I0) has a good relationship with the cobalt ion concentration (cCO2+) added. Thus, the authors developed a fluorescence method for the detection of cobalt ions based on the FRET of silver triangular nanoplates and Rhodamine 6G.


Assuntos
Cobalto/análise , Transferência Ressonante de Energia de Fluorescência , Nanopartículas/química , Rodaminas/química , Soroalbumina Bovina/análise , Prata/química , Animais , Bovinos , Fluorescência , Íons
17.
Biotechnol Lett ; 37(9): 1877-86, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25994580

RESUMO

OBJECTIVES: To acquire a thermostable xylanase, that is suitable for xylooligosaccharide production from pretreated corncobs, the metagenomic method was used to obtain the gene from an uncultured environmental microorganism. RESULTS: A thermostable xylanase-encoding gene (xyn10CD18) was cloned directly from the metagenomic DNA of cow dung compost. When xyn10CD18 was expressed in Bacillus megaterium MS941, extracellular xylansae activity at 106 IU/ml was achieved. The purified recombinant Xyn10CD18 was optimally active at pH 7 and 75 °C as measured over 10 min. It retained over 55% of its initial activity at 70 °C and pH 7 after 24 h. Its action on birchwood xylan for 18 h liberated xylooligosaccharides with 2°-4° of polymerization, with xylobiose and xylotetraose as the main products. When pretreated corncobs were hydrolyzed by Xyn10CD18 for 18 h, the xylooligosaccharides (DP 2-4) products increased to 80% and the xylose was just increased by 3%. CONCLUSION: Xyn10CD18 is a thermostable endoxylanase and is a promising candidate for biomass conversion and xylooligosaccharide production.


Assuntos
Clonagem Molecular/métodos , Endo-1,4-beta-Xilanases/genética , Glucuronatos/biossíntese , Metagenoma , Oligossacarídeos/biossíntese , Animais , Bovinos , Endo-1,4-beta-Xilanases/química , Endo-1,4-beta-Xilanases/metabolismo , Estabilidade Enzimática , Microbiologia do Solo , Temperatura , Zea mays/química
18.
Spectrochim Acta A Mol Biomol Spectrosc ; 137: 1250-7, 2015 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-25305618

RESUMO

In this work, we designed a new fluorescent oligonucleotides-stabilized silver nanoclusters (DNA/AgNCs) probe for sensitive detection of mercury and copper ions. This probe contains two tailored DNA sequence. One is a signal probe contains a cytosine-rich sequence template for AgNCs synthesis and link sequence at both ends. The other is a guanine-rich sequence for signal enhancement and link sequence complementary to the link sequence of the signal probe. After hybridization, the fluorescence of hybridized double-strand DNA/AgNCs is 200-fold enhanced based on the fluorescence enhancement effect of DNA/AgNCs in proximity of guanine-rich DNA sequence. The double-strand DNA/AgNCs probe is brighter and stable than that of single-strand DNA/AgNCs, and more importantly, can be used as novel fluorescent probes for detecting mercury and copper ions. Mercury and copper ions in the range of 6.0-160.0 and 6-240 nM, can be linearly detected with the detection limits of 2.1 and 3.4 nM, respectively. Our results indicated that the analytical parameters of the method for mercury and copper ions detection are much better than which using a single-strand DNA/AgNCs.


Assuntos
Cobre/análise , DNA/química , Corantes Fluorescentes/química , Mercúrio/análise , Nanopartículas Metálicas/química , Prata/química , Sequência de Bases , Cátions Bivalentes/análise , Fluorescência , Guanina/química , Limite de Detecção , Rios/química , Espectrometria de Fluorescência/métodos
19.
J Microbiol Biotechnol ; 24(4): 489-96, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24448166

RESUMO

High levels of extracellular xylanase activity (211.79 IU/mg) produced by Paenibacillus sp. NF1 were detected when it was submerged-cultured. After three consecutive purification steps using Octyl-Sepharose, Sephadex G75, and Q-Sepharose columns, a thermostable xylanase (XynNF) was purified to homogeneity and showed a molecular mass of 37 kDa according to SDS-PAGE. The specific activity of the purified XynNF was up to 3,081.05 IU/mg with a 14.55-fold purification. The activity of XynNF was stimulated by Ca(2+), Ba(2+), DTT, and ß-mercaptoethanol, but was inhibited by Fe(3+), Zn(2+), Fe(2+), Cu(2+), SDS, and EDTA. The purified XynNF displayed a greater affinity for oat spelt xylan with the maximal enzymatic activity at 60°C and pH 6.0. XynNF, which was shown to be cellulose-free, with high stability at high temperature (70°C-80°C) and low pH range (pH 4.0-7.0), is potentially valuable for various industrial applications. The end products of high efficient oat spelt xylan hydrolysis by XynNF (an endoxylanase) containing 95.8% xylooligosaccharides of 2-4 degree of polymerization (DP2-4) with the enrichment of xylobiose (61.5%) indicated that XynNF is a promising candidate for xylooligosaccharides production.


Assuntos
Glucuronatos/metabolismo , Oligossacarídeos/metabolismo , Paenibacillus/enzimologia , Xilosidases/química , Xilosidases/metabolismo , Avena/química , Cromatografia Líquida/métodos , Eletroforese em Gel de Poliacrilamida , Ativadores de Enzimas/análise , Inibidores Enzimáticos/análise , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Hidrólise , Peso Molecular , Temperatura , Xilanos/metabolismo , Xilosidases/isolamento & purificação
20.
BMC Genomics ; 14: 579, 2013 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-23984715

RESUMO

BACKGROUND: Artificial selection played an important role in the origin of modern Glycine max cultivars from the wild soybean Glycine soja. To elucidate the consequences of artificial selection accompanying the domestication and modern improvement of soybean, 25 new and 30 published whole-genome re-sequencing accessions, which represent wild, domesticated landrace, and Chinese elite soybean populations were analyzed. RESULTS: A total of 5,102,244 single nucleotide polymorphisms (SNPs) and 707,969 insertion/deletions were identified. Among the SNPs detected, 25.5% were not described previously. We found that artificial selection during domestication led to more pronounced reduction in the genetic diversity of soybean than the switch from landraces to elite cultivars. Only a small proportion (2.99%) of the whole genomic regions appear to be affected by artificial selection for preferred agricultural traits. The selection regions were not distributed randomly or uniformly throughout the genome. Instead, clusters of selection hotspots in certain genomic regions were observed. Moreover, a set of candidate genes (4.38% of the total annotated genes) significantly affected by selection underlying soybean domestication and genetic improvement were identified. CONCLUSIONS: Given the uniqueness of the soybean germplasm sequenced, this study drew a clear picture of human-mediated evolution of the soybean genomes. The genomic resources and information provided by this study would also facilitate the discovery of genes/loci underlying agronomically important traits.


Assuntos
Genoma de Planta , Glycine max/genética , Teorema de Bayes , Cruzamento , Evolução Molecular , Genética Populacional , Haplótipos , Humanos , Mutação INDEL , Anotação de Sequência Molecular , Filogenia , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Seleção Genética , Análise de Sequência de DNA
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