Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 148
Filtrar
Mais filtros

Bases de dados
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Opt Express ; 31(18): 29440-29451, 2023 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-37710744

RESUMO

Supercontinuum sources with high compactness are essential for applications such as optical sensing, airborne detection and communication systems. In the past decades, the adoption of bulky optical parametric amplifier to pump various chalcogenide glass waveguides are widely reported for on-chip mid-infrared supercontinuum generation, but this usually leads to a large volume of the whole system, and is not practical. Therefore, integrating advanced femtosecond fiber lasers with optical waveguides using nano-fabrication technology are highly desired. However, the scarcity of compact pump sources and the dispersion-matched high-nonlinearity waveguide in short wavelength regions have hindered the advancement of integrated supercontinuum source performances in the near and mid-infrared region. In this study, we demonstrate a broadband supercontinuum source from As2S3 waveguide pumped by a compact dual-femtosecond solitons pulse source. The laser is completely fiber structured, and its wavelength can be readily tuned from 2 to 2.3 µm using Raman soliton self-frequency shift technology in a Tm3+-doped fiber amplifier. Furthermore, the As2S3 waveguide is designed with controllable dispersion and high nonlinearity for a broadband supercontinuum generation. These results will advance the development of on-chip supercontinuum sources based on chalcogenide waveguides.

2.
Opt Express ; 30(2): 3089-3100, 2022 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-35209435

RESUMO

We demonstrate the tunable Raman femtosecond solitons generation with a record-breaking power of 1.2 W at 2.3 µm and an ever-reported highest Raman soliton energy conversion efficiency of 99% via precise seed-pulse management in the thulium-doped single-mode fiber amplifier. We find that the central wavelength and the chirp of the incident pulses could dramatically affect the red-shifted soliton energy, locations, conversion efficiency, and the threshold power in fundamental Raman soliton generation. For the first time, we experimentally illustrated how the seed pulse with Kelly sidebands could affect the Raman solitons generation in this amplifier, and obtained the detailed regularity between the parameters of incident pulses and the properties of the generated solitons. This work provides useful guidance for Raman soliton-based high-power mid-infrared femtosecond laser fabrication.

3.
Opt Lett ; 47(1): 34-37, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34951876

RESUMO

We demonstrate a thulium-doped mode-locked fiber laser with ultra-broadband wavelength tunability for micro-strain sensing based on the multimode interference (MMI) effect in single-mode-multimode-single-mode (SMS) fiber configuration. The homemade SMS device with high performance is fusion spliced in the laser cavity, and the developed dispersion precisely managed the all-fiber structured mode-locked picosecond laser with a record-breaking wavelength tuning range from 1976 to 1916 nm while exerting axial strain on this SMS device. We experimentally explored the regularity between the strain and the central-wavelength shift of the mode-locked pulse, and for the first time to the best of the authors' knowledge, achieved the precise in-line axial strain measurement from 0 to 5385 µÉ› by using the tunable ultrafast-laser-based sensor, and sensitivity is up to -11.5 pm/µÉ›. With high compactness and durability, this sensor has advantages in real-time dynamic measurement over other passive devices, thus will undoubtedly find various application scenarios.

4.
Opt Express ; 29(3): 4048-4057, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33770992

RESUMO

We demonstrate a watt-level mid-infrared supercontinuum source, with the spectrum covering the infrared region from 2 to 6.5 µm, in an all-fiber structured laser transmission system. To further improve the SC spectral bandwidth, power and system compactness in the follow-up As2S3 fiber, we theoretically and experimentally explored some knotty problems that would potentially result in the As2S3 fiber end-facet failure and low SC output power during the high-power butt-coupling process and proposed an optimal coupling distance on the premise of the safety of As2S3 fiber end face. In addition, we also built a multi-pulse pumping model for the first time to more precisely estimate the SC spectral evolution in As2S3 fiber. This work will give an important reference to someone who is working on the all-fiber structured, high-power mid- and far-infrared supercontinuum source.

5.
Appl Microbiol Biotechnol ; 104(13): 5959-5972, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32409945

RESUMO

Previous studies showed that probiotics supplementation contributed to alleviate obesity. This work was to assess the efficacy of Lactobacillus plantarum FRT10 from sour dough in alleviating obesity in mice fed with a high-fat diet (HFD), and the underlying mechanisms focusing on modulation of the gut microbiota profile. Kunming mice were fed with a regular diet (CT), a high-fat diet (HFD), and two HFDs containing low and high doses of L. plantarum FRT10 for 8 weeks. The physiological and biochemical modulations in liver were analyzed. Cecal contents were analyzed by high-throughput 16S ribosomal RNA sequencing. FRT10 supplementation significantly reduced body weight gain, fat weight, and liver triacylglycerols (TGs) and alanine aminotransferase (ALT) concentrations (P < 0.05). FRT10 significantly ameliorated the HFD-induced gut dysbiosis, as evidenced by increased abundance of microbes, including Butyricicoccus, Butyricimonas, Intestinimonas, Odoribacter, and Alistipes, and decreased abundance of Desulfovibrionaceae, Roseburia, and Lachnoclostridium. Lactobacillus, Bifidobacterium, and Akkermansia were markedly increased after FRT10 intervention. In addition, real-time quantitative PCR revealed that FRT10 upregulated the mRNA expression levels of peroxisome proliferator-activated receptor-α (PPARα) and carnitine palmitoyltransferase-1α (CPT1α), and downregulated the mRNA expression levels of sterol regulatory element-binding protein 1 (SREBP-1) and TG-synthesizing enzyme diacylglycerol acyltransferase 1 (DGAT1) in liver. These findings suggested that FRT10 had anti-obesity effects in obese mice partly related to the activation of PPARα/CPT1α pathway. FRT10 can be considered a single probiotic agent for preventing HFD-induced obesity in humans and animals.


Assuntos
Microbioma Gastrointestinal/efeitos dos fármacos , Lactobacillus plantarum/fisiologia , Obesidade/tratamento farmacológico , PPAR alfa/metabolismo , Probióticos/administração & dosagem , Transdução de Sinais/efeitos dos fármacos , Animais , Carnitina O-Palmitoiltransferase/genética , Carnitina O-Palmitoiltransferase/metabolismo , Dieta Hiperlipídica/efeitos adversos , Feminino , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/genética , Fígado/efeitos dos fármacos , Fígado/metabolismo , Camundongos , Camundongos Obesos , Obesidade/metabolismo , Obesidade/microbiologia , PPAR alfa/genética , Probióticos/farmacologia , Aumento de Peso/efeitos dos fármacos
6.
Opt Express ; 27(7): 10311-10319, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31045175

RESUMO

We demonstrated an ultrabroadband supercontinuum (SC) generation with high coherence property in all-normal-dispersion (ANDi) Te-based chalcogenide tapered fiber. The fibers made of Ge20As20Se15Te45 core and Ge20As20Se20Te40 cladding glasses were fabricated via isolated stacked extrusion. The waist diameter and length can be accurately controlled by a homemade tapering platform. When the core diameter of the waist was ≤14 µm, the fiber showed an ANDi characteristic in the wavelength range of 1.7-14 µm. A coherent SC generation covered 1.7-12.7 µm was generated in a 7-cm-long tapered fiber, pumped at 5.5 µm. To the best of our knowledge, this is the first SC experimental demonstration in Te-based step-index tapered fiber and the broadest SC generation in chalcogenide tapered fiber when pumped in the normal dispersion regime so far.

7.
Biomed Chromatogr ; 33(12): e4687, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31441946

RESUMO

In recent years, the fingerprint of high-performance liquid chromatography has been extensively applied in the identification and quality control of traditional Chinese medicine. It can be a potential protocol for assessing the authenticity, stability and consistency of traditional Chinese medicine and guaranteeing the expected biological activity. In this paper, a method using high-performance liquid chromatography to identify and control the quality of the extract of Taraxacum mongolicum Hand.-Mazz. (TME) was established. With this method, the correlation coefficients of the similarity of 10 batches were ≥0.994. The TME displayed a steady proliferative effect in Lactobacillus plantarum. In brief, this study successfully built a reliable, simple and efficient method to control and confirm the quality and the stability of biological activity of the TME.


Assuntos
Proliferação de Células/efeitos dos fármacos , Lactobacillus plantarum/efeitos dos fármacos , Extratos Vegetais , Taraxacum/química , Cromatografia Líquida de Alta Pressão , Extratos Vegetais/análise , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Extratos Vegetais/normas , Controle de Qualidade , Reprodutibilidade dos Testes
8.
Opt Lett ; 43(8): 1730-1733, 2018 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-29652351

RESUMO

We implement an ultrafast Yb-doped all-fiber laser which incorporates tapered single-mode fibers for managing nonlinearity and dispersion. The tapered fiber placed in the oscillator cavity aims to broaden the optical spectrum of the intracavity pulse. At the oscillator output, we use another tapered fiber to perform pulse compression. The resulting 66.1-MHz Yb-doped all-fiber oscillator self-starts and generates 0.4-nJ, 65-fs pulses, which can serve as a compact and robust seed source for subsequent high-power, high-energy amplifiers.

9.
Biomed Chromatogr ; 32(12): e4354, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30074251

RESUMO

Similarity evaluation of complicated chromatographic profiles is a potential protocol for the identification and quality control of herbal medicinal products to ensure their biological activity. In this work, a high-performance liquid chromatography method was established for controlling the batch quality of the extract from Portulaca oleracea L. Using this method, the coefficients of correlation of the similarity of 10 batches extract of P. oleracea L. were ≥ 0.97. The 10 batch extracts from P. oleracea L. possessed stable antiproliferative activity in Aspergillus flavus. The antiproliferative activity stability is correlated with the stability quality of the of the extract from P. oleracea L. Therefore, the present study successfully set up a sensitive and efficient method which might be used to guarantee stable biological activity of the extract from P. oleracea L.


Assuntos
Antifúngicos/normas , Aspergillus flavus/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Extratos Vegetais/normas , Portulaca/química , Antifúngicos/química , Antifúngicos/farmacologia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Plantas Medicinais/química , Controle de Qualidade , Reprodutibilidade dos Testes
10.
Appl Environ Microbiol ; 82(4): 1004-1014, 2016 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-26637601

RESUMO

N-Glycosylation can modulate enzyme structure and function. In this study, we identified two pepsin-resistant histidine acid phosphatase (HAP) phytases from Yersinia kristensenii (YkAPPA) and Yersinia rohdei (YrAPPA), each having an N-glycosylation motif, and one pepsin-sensitive HAP phytase from Yersinia enterocolitica (YeAPPA) that lacked an N-glycosylation site. Site-directed mutagenesis was employed to construct mutants by altering the N-glycosylation status of each enzyme, and the mutant and wild-type enzymes were expressed in Pichia pastoris for biochemical characterization. Compared with those of the N-glycosylation site deletion mutants and N-deglycosylated enzymes, all N-glycosylated counterparts exhibited enhanced pepsin resistance. Introduction of the N-glycosylation site into YeAPPA as YkAPPA and YrAPPA conferred pepsin resistance, shifted the pH optimum (0.5 and 1.5 pH units downward, respectively) and improved stability at acidic pH (83.2 and 98.8% residual activities at pH 2.0 for 1 h). Replacing the pepsin cleavage sites L197 and L396 in the immediate vicinity of the N-glycosylation motifs of YkAPPA and YrAPPA with V promoted their resistance to pepsin digestion when produced in Escherichia coli but had no effect on the pepsin resistance of N-glycosylated enzymes produced in P. pastoris. Thus, N-glycosylation may improve pepsin resistance by enhancing the stability at acidic pH and reducing pepsin's accessibility to peptic cleavage sites. This study provides a strategy, namely, the manipulation of N-glycosylation, for improvement of phytase properties for use in animal feed.


Assuntos
6-Fitase/química , 6-Fitase/metabolismo , Fosfatase Ácida/química , Fosfatase Ácida/metabolismo , Glicosilação , Pepsina A/metabolismo , Yersinia/enzimologia , 6-Fitase/genética , Fosfatase Ácida/genética , Estabilidade Enzimática , Expressão Gênica , Concentração de Íons de Hidrogênio , Mutagênese Sítio-Dirigida , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Pichia/genética , Pichia/metabolismo , Proteólise
11.
Opt Express ; 24(25): 28400-28408, 2016 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-27958550

RESUMO

In this study, the supercontinuum (SC) generation in a 1-m-long As2S3 fiber with a 200 µm core diameter was demonstrated experimentally. The high-purity As2S3 fiber we used exhibited very low optical loss with a background loss of approximately 0.1 dB/m at a wavelength of 2-5 µm. SC generation was studied by pumping the fiber at different wavelengths and different peak powers. A strong spectral broadening with a 30 dB spectral flatness spanning from 1.4 to 7.0 µm was obtained when the fiber was pumped with 150 fs short pulses at 5.0 µm. The SC generation in bent fiber was also studied. The result showed that the bending radius of the fiber will significantly affect the SC spectra bandwidth and the output power. The SC spectra in the used fiber could still be maintained when it was bent to a radius of 5 cm.

12.
Protein Expr Purif ; 119: 45-50, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26581777

RESUMO

G13 is a 19-residue cationic antimicrobial peptide derived from granulysin. In order to achieve high-level expression of G13 in Escherichia coli cells, and to reduce downstream processing costs, we introduced an Asp-Pro acid labile bond between the His-Patch thioredoxin and G13 and constructed the recombinant plasmid pThiohisA-DP-G13. The plasmid was transformed into E. coli BL21 (DE3). After induction with isopropyl-ß-d-thiogalactopyranoside for 5 h, the fusion protein accumulated up to 200 mg/L in soluble form. The fusion protein was released by a high pressure homogenizer, cleaved using 13% acetic acid at 50 °C hydrolysis for 72 h. The recombinant G13 (r-G13) was then successively purified by fractional precipitation with ammonium sulfate and trichloroacetic acid, followed by one-step cation exchange chromatography. The purified r-G13 displayed a single band (about 2.2 kDa) as analyzed by Tris-Tricine buffered SDS-PAGE, and its precise molecular weight was confirmed using tandem mass spectrometry. Analysis of r-G13 by circular dichroism (CD) indicated that r-G13 contained predominantly ß-sheet and random coil. Agar plate diffusion assay revealed that the r-G13 exhibited antibacterial activity against both Bacillus subtilis and E. coli.


Assuntos
Antibacterianos/biossíntese , Peptídeos Catiônicos Antimicrobianos/biossíntese , Fragmentos de Peptídeos/biossíntese , Proteínas Recombinantes de Fusão/biossíntese , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Antígenos de Diferenciação de Linfócitos T/química , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/isolamento & purificação , Peptídeos Catiônicos Antimicrobianos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Sequência de Bases , Precipitação Química , Cromatografia por Troca Iônica , Escherichia coli/efeitos dos fármacos , Expressão Gênica , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/isolamento & purificação , Fragmentos de Peptídeos/farmacologia , Estrutura Secundária de Proteína , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/farmacologia , Solubilidade
13.
Biochem Biophys Res Commun ; 457(1): 83-9, 2015 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-25542153

RESUMO

The tripartite motif (TRIM)-containing proteins exhibit various activities and play important roles in the immune system through regulating signaling pathways. Bloodthirsty gene is a multigene subset of TRIM genes. In this study we identified and characterized a new member of the bloodthirsty subset of TRIM genes, btr20, in zebrafish (Danio rerio). The gene is located on chromosome 19 and forms a cluster with btr18, btr21, btr22 and an E3 ubiquitin ligase TRIM39-like gene. Deduced btr20 represents a RBCC-B30.2 TRIM protein containing 544 amino acids. The mRNA expression level of btr20 was highest in intestine and gill, followed by in spleen and kidney. Challenge experiment with Aeromonas hydrophila strain NJ-1 showed that the levels of btr20 and NF-κB mRNA were remarkably upregulated in the four tissues mentioned above. btr20 was localized in the cytoplasm and formed aggregate in human embryonic kidney cell line 293T. In vitro self-ubiquitylation experiment demonstrated that btr20 has E3 ubiquitin ligase activity that can be self-ubiquitylated with most E2 enzymes, especially UbcH6. The results suggested that btr20 may involve in the anti-microbial activity in the immune system as an E3 ubiquitin ligase.


Assuntos
Aeromonas/imunologia , Infecções Bacterianas/imunologia , Infecções Bacterianas/microbiologia , Ubiquitina-Proteína Ligases/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Peixe-Zebra/imunologia , Peixe-Zebra/microbiologia , Sequência de Aminoácidos , Animais , Perfilação da Expressão Gênica , Células HEK293 , Humanos , Espaço Intracelular/metabolismo , Dados de Sequência Molecular , Transporte Proteico , Análise de Sequência de Proteína , Frações Subcelulares/metabolismo , Ubiquitina-Proteína Ligases/química , Ubiquitina-Proteína Ligases/genética , Ubiquitinação , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/química , Proteínas de Peixe-Zebra/genética
14.
Appl Microbiol Biotechnol ; 99(3): 1261-72, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25487894

RESUMO

Thermophilic Neosartorya fischeri P1 is an excellent carbohydrate-active enzyme (CAZyme) producer. Two α-galactosidases of GH (glycoside hydrolase ) family 27 with a very low sequence identity (28.7%), Gal27A and Gal27B, were identified in strain P1 and functionally expressed in Pichia pastoris. In comparison to other characterized GH27 fungal counterparts, rGal27B has a higher temperature optimum (75 °C) and better thermostability (>50% activity at 70 °C for 15 min), and rGal27A shows stability over the broadest pH range (pH 2.0-12.0). Moreover, great distinctions lie in the two enzymes. When using pNPG as the substrate, rGal27B had a higher turnover number (1621.4 vs. 368.3 s(-1)) but lower affinity (2.84 vs. 0.8 mM) and catalytic efficiency (460.8 vs. 580.3 s(-1) mM(-1)) than rGal27A. rGal27B acted on galacto-oligosaccharides, whereas rGal27A was active on polymeric substrates. Although both enzymes showed synergy in galactomannan degradation when combined with a ß-mannanase of the same strain, enzyme combinations including rGal27A released more reducing sugars (up to 11.67-fold). Homology modeling predicts different loops in N. fischeri α-galactosidases, highlighting the larger tunnel structure in Gal27A to accommodate/bind branched galactomannan with high galactose contents. Phylogenetic analysis reveals the far relationship of Gal27A and Gal27B that they may evolve in different action modes, and their coexistence widens the substrate spectrum for nutrient utilization. This study illustrates the substrate profiles and synergistic mechanism of GH27 α-galactosidases of different structures.


Assuntos
Proteínas Fúngicas/química , Neosartorya/enzimologia , alfa-Galactosidase/química , Sequência de Aminoácidos , Estabilidade Enzimática , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Galactose/análogos & derivados , Temperatura Alta , Concentração de Íons de Hidrogênio , Cinética , Mananas/metabolismo , Dados de Sequência Molecular , Neosartorya/química , Neosartorya/classificação , Neosartorya/genética , Filogenia , Alinhamento de Sequência , Especificidade por Substrato , alfa-Galactosidase/genética , alfa-Galactosidase/metabolismo , beta-Manosidase/química , beta-Manosidase/genética , beta-Manosidase/metabolismo
15.
Appl Environ Microbiol ; 80(11): 3426-32, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24657866

RESUMO

Efficient degradation of plant polysaccharides in rumen requires xylanolytic enzymes with a high catalytic capacity. In this study, a full-length xylanase gene (xynA) was retrieved from the sheep rumen. The deduced XynA sequence contains a putative signal peptide, a catalytic motif of glycoside hydrolase family 10 (GH10), and an extra C-terminal proline-rich sequence without a homolog. To determine its function, both mature XynA and its C terminus-truncated mutant, XynA-Tr, were expressed in Escherichia coli. The C-terminal oligopeptide had significant effects on the function and structure of XynA. Compared with XynA-Tr, XynA exhibited improved specific activity (12-fold) and catalytic efficiency (14-fold), a higher temperature optimum (50°C versus 45°C), and broader ranges of temperature and pH optima (pH 5.0 to 7.5 and 40 to 60°C versus pH 5.5 to 6.5 and 40 to 50°C). Moreover, XynA released more xylose than XynA-Tr when using beech wood xylan and wheat arabinoxylan as the substrate. The underlying mechanisms responsible for these changes were analyzed by substrate binding assay, circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC), and xylooligosaccharide hydrolysis. XynA had no ability to bind to any of the tested soluble and insoluble polysaccharides. However, it contained more α helices and had a greater affinity and catalytic efficiency toward xylooligosaccharides, which benefited complete substrate degradation. Similar results were obtained when the C-terminal sequence was fused to another GH10 xylanase from sheep rumen. This study reveals an engineering strategy to improve the catalytic performance of enzymes.


Assuntos
Xilanos/metabolismo , Xilosidases/genética , Xilosidases/metabolismo , Animais , Calorimetria , Domínio Catalítico , Dicroísmo Circular , Clonagem Molecular , Estabilidade Enzimática , Escherichia coli/enzimologia , Escherichia coli/genética , Fagus/química , Expressão Gênica , Concentração de Íons de Hidrogênio , Hidrólise , Ligação Proteica , Conformação Proteica , Sinais Direcionadores de Proteínas , Estrutura Terciária de Proteína , Rúmen/microbiologia , Análise de Sequência de DNA , Ovinos , Temperatura , Triticum/química , Xilosidases/química , Xilosidases/isolamento & purificação
16.
Appl Microbiol Biotechnol ; 98(5): 2155-63, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23900799

RESUMO

The gene man5XZ3 from Aspergillus nidulans XZ3 encodes a multimodular ß-mannanase of glycoside hydrolase family 5 that consists of a family 1 carbohydrate-binding module (CBM1), a Thr/Ser-rich linker region, and a catalytic domain. Recombinant Man5XZ3 and its two truncated derivatives, Man5ΔCBM (removing the CBM1) and Man5ΔCL (removing both the CBM1 and linker region), were produced in Pichia pastoris and showed significant variance in the secondary structure. The three enzymes had similar biochemical properties, such as optimal pH and temperature (pH 5.0 and 80 °C) and excellent pH stability at pH 4.0-10.0. Removal of the CBM1 alone could improve the thermostability of Man5XZ3, but further removal of the linker region resulted in worse thermostability. Man5XZ3 retained greater enzyme activity in the presence of an organic solvent (acetone), two detergents (SDS and Triton X-100), and a chaotropic agent (urea) compared with Man5ΔCBM and Man5ΔCL. This study provides an excellent ß-mannanase candidate favorable for various industries and primarily demonstrates the relationship between enzyme structure and function.


Assuntos
Aspergillus nidulans/enzimologia , Manosidases/isolamento & purificação , Manosidases/metabolismo , Aspergillus nidulans/genética , Sítios de Ligação , Análise Mutacional de DNA , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Manosidases/química , Manosidases/genética , Dados de Sequência Molecular , Pichia/genética , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Deleção de Sequência , Temperatura
17.
Appl Microbiol Biotechnol ; 98(11): 5019-28, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24584459

RESUMO

A multimodular pectinase of glycoside hydrolase family 28, S6A, was identified in Penicillium oxalicum SX6 that consists of an N-terminal catalytic domain of pectin methylesterase, a Thr/Ser-rich linker region, and a C-terminal catalytic domain of polygalacturonase. Recombinant S6A and its two derivatives, S6PE (the catalytic domain of pectin methylesterase) and S6PG (the catalytic domain of polygalacturonase), were produced in Pichia pastoris. S6A was a bifunctional protein and had both pectin methylesterase and polygalacturonase activities. Three enzymes showed similar biochemical properties, such as optimal pH and temperature (pH 5.0 and 50 °C) and excellent stability at pH 3.5-6.0 and 40 °C. Most metal ions tested (Na(+), K(+), Ca(2+), Li(+), Co(2+), Cr(3+), Ni(2+), Cu(2+), Mn(2+),Mg(2+), Fe(3+), Zn(2+), and Pb(2+)) enhanced the pectin methylesterase activities of S6PE and S6A, but had little or inhibitory effects on the polygalacturonase activities of S6A and S6PG. In comparison with most fungal pectin methylesterases, S6A had higher specific activity (271.1 U/mg) towards 70 % DM citrus pectin. When S6PE and S6PG were combined at the activity ratio of 1:4, the most significant synergistic effect was observed in citrus pectin degradation and degumming of sisal fiber, which is comparable with the performance of S6A (95 v.s. 100 % and 16.9 v.s. 17.2 %, respectively). To the best of our knowledge, this work represents the first report of gene cloning, heterologous expression, and biochemical characterization of a bifunctional pectinase with separate catalytic domains.


Assuntos
Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/metabolismo , Penicillium/enzimologia , Poligalacturonase/genética , Poligalacturonase/metabolismo , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/isolamento & purificação , Domínio Catalítico , Citrus/química , Clonagem Molecular , DNA Fúngico/química , DNA Fúngico/genética , Ativadores de Enzimas/metabolismo , Estabilidade Enzimática , Expressão Gênica , Concentração de Íons de Hidrogênio , Metais/metabolismo , Dados de Sequência Molecular , Pectinas/metabolismo , Penicillium/genética , Poligalacturonase/química , Poligalacturonase/isolamento & purificação , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Análise de Sequência de DNA , Temperatura
18.
J Anim Sci Biotechnol ; 15(1): 31, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38378651

RESUMO

BACKGROUND: Fatty liver hemorrhage syndrome (FLHS) becomes one of the most major factors resulting in the laying hen death for caged egg production. This study aimed to investigate the therapeutic effects of Lactiplantibacillus plantarum (Lp. plantarum) FRT4 on FLHS model in laying hen with a focus on liver lipid metabolism, and gut microbiota. RESULTS: The FLHS model of laying hens was established by feeding a high-energy low-protein (HELP) diet, and the treatment groups were fed a HELP diet supplemented with differential proportions of Lp. plantarum FRT4. The results indicated that Lp. plantarum FRT4 increased laying rate, and reduced the liver lipid accumulation by regulating lipid metabolism (lipid synthesis and transport) and improving the gut microbiota composition. Moreover, Lp. plantarum FRT4 regulated the liver glycerophospholipid metabolism. Meanwhile, "gut-liver" axis analysis showed that there was a correlation between gut microbiota and lipid metabolites. CONCLUSIONS: The results indicated that Lp. plantarum FRT4 improved the laying performance and alleviated FLHS in HELP diet-induced laying hens through regulating "gut-liver" axis. Our findings reveal that glycerophospholipid metabolism could be the underlying mechanism for the anti-FLHS effect of Lp. plantarum FRT4 and for future use of Lp. plantarum FRT4 as an excellent additive for the prevention and mitigation of FLHS in laying hens.

19.
Antioxidants (Basel) ; 13(5)2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38790683

RESUMO

The natural edible characteristics of Chinese herbs have led more and more people to study them as an alternative product to antibiotics. In this study, crude extracts of Glycyrrhiza radix and Atractylodes macrocephala (abbreviated as GRAM) with glycyrrhizic acid content not less than 0.2 mg/g were selected to evaluate the effects of GRAM on the immune and antioxidant capacity of model animals. Thirty 21-day-old male Leghorn chickens were weighed and randomly assigned to one of three groups of ten animals each. The treatments comprised a control group (CON), in which saline was injected at day 31, day 33, and day 35, an LPS-treated group (LPS), in which LPS (0.5 mg/kg of BW) was injected at day 31, day 33, and day 35, and finally a GRAM and LPS-treated group, (G-L) in which a GRAM-treated diet (at GRAM 2 g/kg) was fed from day 21 to day 35 with LPS injection (0.5 mg/kg of BW) at day 31, day 33, and day 35. The results of diarrhea grade and serum antioxidant measurement showed that the LPS group had obvious diarrhea symptoms, serum ROS and MDA were significantly increased, and T-AOC was significantly decreased. The oxidative stress model of LPS was successfully established. The results of immune and antioxidant indexes showed that feeding GRAM significantly decreased levels of the pro-inflammatory factors TNF-α, IL-1ß, and IL-6 (p < 0.05) and significantly increased levels of the anti-inflammatory factors IL-4 and IL-10 and levels of the antioxidant enzymes GSH-Px and CAT (p < 0.05). GRAM resisted the influence of LPS on ileum morphology, liver, and immune organs and maintained normal index values for ileum morphology, liver, and immune organs. In summary, this study confirmed the antidiarrheal effect of GRAM, which improved the immune and antioxidant capacity of model animals by regulating inflammatory cytokine levels and antioxidant enzyme activity in poultry.

20.
Appl Environ Microbiol ; 79(6): 1990-5, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23335774

RESUMO

We cloned a Paenibacillus sp. strain E18 5.3-kb xylanolytic gene cluster that contains three open reading frames encoding two family 43 α-L-arabinofuranosidases (Abf43A and Abf43B) and one family 10 xylanase (XynBE18). The deduced amino acid sequences of Abf43A and Abf43B were at most 68% and 63% identical to those of two putative family 43 proteins from Clostridium sp. strain DL-VIII (EHI98634.1 and EHI98635.1), respectively, but were only 11% identical to each other. Recombinant Abf43A and Abf43B had similar activities at 45°C and pH 6.0 but varied in thermostabilities and substrate specificities. Abf43B was active against only 4-nitrophenyl α-L-arabinofuranoside, whereas Abf43A acted on 4-nitrophenyl α-L-arabinofuranoside, wheat arabinoxylan, 4-nitrophenyl α-D-xylopyranoside, and sugar beet arabinan. The sequential and combined effects on xylan degradation by XynBE18, Abf43A, and Abf43B were characterized. For beechwood, birchwood, and oat spelt xylans as the substrates, synergistic effects were found when XynBE18 and Abf43A or Abf43B were incubated together and when the substrates were first incubated with Abf43A or Abf43B and then with XynBE18. Further high-performance liquid chromatography (HPLC) analysis showed that the amounts of xylobiose and xylose increased sharply in the aforementioned reactions. For water-soluble wheat arabinoxylan as the substrate, Abf43A not only released arabinose but also had a synergistic effect with XynBE18. Synergy may arise as the result of removal of arabinose residues from xylans by α-L-arabinofuranosidases, which eliminates steric hindrance caused by the arabinose side chains and which allows xylanases to then degrade the xylan backbone, producing short xylooligosaccharides.


Assuntos
Glicosídeo Hidrolases/metabolismo , Paenibacillus/enzimologia , Xilanos/metabolismo , Xilosidases/metabolismo , Arabinose/metabolismo , Avena/química , Betula/química , DNA Bacteriano/química , DNA Bacteriano/genética , Dissacarídeos/metabolismo , Estabilidade Enzimática , Fagus/química , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Concentração de Íons de Hidrogênio , Hidrólise , Dados de Sequência Molecular , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , Temperatura , Madeira/química , Xilanos/isolamento & purificação , Xilose/metabolismo , Xilosidases/química , Xilosidases/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA