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Converting fatty acids into specialty chemicals is sustainable but hindered by the low efficiency and thermal instability of current oleic acid hydratases, along with mass transfer limitations in emulsion reactions. This study introduces an optimized continuous flow micro-reactor (CFMR) that efficiently transforms oleic acid at low (15 g·L-1) and high (50 g·L-1) concentrations, improving reaction efficiency and overcoming key conversion barriers. The first CFMR model showed reaction speeds surpassing traditional batch stirred tank reactors (BSTR). Optimizations were performed on three key components: liquid storage, mixer, and reaction section of the CFMR, with each round's best conditions carried into the next. This achieved a space-time yield of 597 g·L-1·d-1 at a 15 g·L-1 oleic acid load. To further enhance the yield, we optimized the emulsifier system to solve incomplete emulsification and developed a two-component feed microreactor (TCFMR) that addressed substrate and product inhibition at high loads, reaching a 91% conversion of 50 g·L-1 oleic acid in 30 minutes, with a space-time yield of 2312 g·L-1·d-1. These advancements represent significant progress in utilizing fatty acids and advancing sustainable chemical synthesis.
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BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative disease with an insidious onset. The widespread application of omics techniques in AD has attracted considerable attention. We aimed to make a comprehensive analysis of published omics articles on AD in order to determine the research profile and application trends of omics techniques in AD. METHODS: This study utilizes bibliometric and visual methods including a map collaboration map, co-citations, and keywords to identify knowledge structures, hot topics, and research trends based on 6,828 publications from the Web of Science Core Collection (WoSCC) database. RESULTS: The results of this study showed that 5654 institutions from 91 countries published articles in this field. The USA, China, and the UK played a leading role in publishing numerous articles in relevant journals as well as prolific institutions and authors, respectively. This paper collects a large number of literatures on the application of AD omics technology from the WoSCC database and found the omics technology applied to AD is mainly based on genomics technology. The application of transcriptomics technology has shown an increasing trend in recent years, and the application of multi-omics technology will be the general trend in the future. CONCLUSION: The development status, frontier hotspots, and general trends of omics application technologies are reviewed. This article will provide intelligence support to researchers and institutions in the field of Alzheimer's omics research and applications from a practical perspective.
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Enfermedad de Alzheimer , Enfermedades Neurodegenerativas , Humanos , Bibliometría , China , Bases de Datos FactualesRESUMEN
The P450-mediated terminal hydroxylation of non-activated C-H bonds is a chemically challenging reaction. CYP153A7 monooxygenase, discovered in Sphingomonas sp. HXN200, belongs to the CYP153A subfamily and shows a pronounced terminal selectivity. Herein, we report the significantly improved terminal hydroxylation activity of CYP153A7 by redesign of the substrate binding pocket based on molecular docking of CYP153A7-C8:0 and sequence alignments. Some of the resultant single mutants were advantageous over the wild-type enzyme with higher reaction rates, achieving a complete conversion of n-octanoic acid (C8:0, 1â mM) in a shorter time period. Especially, a single-mutation variant, D258E, showed 3.8-fold higher catalytic efficiency than the wild type toward the terminal hydroxylation of medium-chain fatty acid C8:0 to the high value-added product 8-hydroxyoctanoic acid.
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Sistema Enzimático del Citocromo P-450 , Ácidos Grasos , Dominio Catalítico , Sistema Enzimático del Citocromo P-450/metabolismo , Ácidos Grasos/química , Hidroxilación , Simulación del Acoplamiento Molecular , Especificidad por SustratoRESUMEN
Lithium-sulfur batteries (LSBs) are still limited by the shuttle of lithium polysulfides (LiPS) and the slow Li-S reaction. Herein, we demonstrate that when using cobalt sulfide as a catalytic additive, an external magnetic field generated by a permanent magnet can significantly improve the LiPS adsorption ability and the Li-S reaction kinetics. More specifically, the results show both experimentally and theoretically how an electron spin polarization of Co ions reduces electron repulsion and enhances the degree of orbital hybridization, thus resulting in LSBs with unprecedented performance and stability. Under an external magnetic field, LSBs with 0.0084 % per cycle decay rate at 2â C during 8150â cycles are produced. Overall, this work not only demonstrates an effective strategy to promote LiPS adsorption and electrochemical conversion in LSBs at no additional energy cost but also enriches the application of the spin effect in the electrocatalysis fields.
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Oleate hydratase catalyzes the hydration of unsaturated fatty acids, giving access to C10-functionalization of oleic acid. The resultant 10-hydroxystearic acid is a key material for the synthesis of many biomass-derived value-added products. Herein, we report the engineering of an oleate hydratase from Paracoccus aminophilus (PaOH) with significantly improved catalytic efficiency (from 33 s-1 mM-1 to 119 s-1 mM-1), as well as 3.4 times increased half-life at 30 °C. The structural mechanism regarding the impact of mutations on the improved catalytic activity and thermostability was elucidated with the aid of molecular dynamics simulation. The practical feasibility of the engineered PaOH variant F233L/F122L/T15 N was demonstrated through the pilot synthesis of 10-hydroxystearic acid and 10-oxostearic acid via an optimized multi-enzymatic cascade reaction, with space-time yields of 540 g L-1 day-1 and 160 g L-1 day-1, respectively.
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Carbono/metabolismo , Ingeniería Genética , Hidroliasas/metabolismo , Ácido Oléico/metabolismo , Biocatálisis , Ensayos Analíticos de Alto Rendimiento , Cinética , Simulación de Dinámica Molecular , Mutagénesis/genética , Paracoccus/enzimología , Ácidos Esteáricos/metabolismoRESUMEN
Baeyer-Villiger monooxygenases (BVMOs) are remarkable biocatalysts for the Baeyer-Villiger oxidation of ketones to generate esters or lactones. The regioselectivity of BVMOs is essential for determining the ratio of the two regioisomeric products ("normal" and "abnormal") when catalyzing asymmetric ketone substrates. Starting from a known normal-preferring BVMO sequence from Pseudomonas putida KT2440 (PpBVMO), a novel BVMO from Gordonia sihwensis (GsBVMO) with higher normal regioselectivity (up to 97/3) was identified. Furthermore, protein engineering increased the specificity constant (kcat /KM ) 8.9-fold to 484â s-1 mM-1 for 10-ketostearic acid derived from oleic acid. Consequently, by using the variant GsBVMOC308L as an efficient biocatalyst, 10-ketostearic acid was efficiently transformed into 9-(nonanoyloxy)nonanoic acid, with a space-time yield of 60.5â g L-1 d-1 . This study showed that the mutant with higher regioselectivity and catalytic efficiency could be applied to prepare medium-chain ω-hydroxy fatty acids through biotransformation of long-chain aliphatic keto acids derived from renewable plant oils.
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Oxigenasas de Función Mixta/metabolismo , Ingeniería de Proteínas , Actinobacteria/enzimología , Biocatálisis , Oxigenasas de Función Mixta/genética , Mutagénesis Sitio-Dirigida , Ácido Oléico/química , Ácido Oléico/metabolismo , Oxidación-Reducción , Pseudomonas putida/enzimología , Ácidos Esteáricos/química , Ácidos Esteáricos/metabolismo , Estereoisomerismo , Especificidad por SustratoRESUMEN
BACKGROUND: Osteoarthritis (OA) is a non-inflammatory degenerative disease, with progressive damages on the articular cartilages. In recent years, researchers have paid many efforts in the diagnostics and treatments of OA. However, no effective therapeutic method has been revealed to help inhibit the development of OA. Herein, we studied the roles and associations of PCAT-1 and miR-27-3p in the pathogenesis OA. METHODS: OA articular cartilages and healthy articular cartilages were isolated for investigation. The chondrocytes were isolated from articular cartilage samples. QRT-PCR and western blotting were used for the detection of expression of genes and proteins. cell Titer 96® AQueous one proliferation kit was applied for detect cell viability of Chondrocytes transfected with negative control vector, pcDNA3.1 PCAT-1 plasmid or siRNA against PCAT-1. RNA pull-down assays and Luciferase reporter assay were used to confirm the connection. SPSS 17.0 was employed for statistical analysis. RESULTS: We found that the expressions of PCAT-1 were up-regulated in OA chondrocytes compared with normal chondrocytes. si-PCAT-1 suppressed apoptotic OA chondrocytes. Over-expression of PCAT-1 enhanced the apoptosis of normal chondrocytes. In addition, the online database and luciferase assay confirmed that PCAT-1 could directly target miR-27b-3p. PCAT-1 could promote the apoptosis of OA and normal chondrocytes through binding with miR-27b-3p. CONCLUSIONS: Based on the comparisons and analysis, we could conclude that lncRNA PCAT-1 regulated the apoptosis of chondrocytes through sponging miR-27b-3p in OA. PCAT-1 has potential values to act as a new therapeutic target for OA patients.
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Apoptosis/genética , Condrocitos/metabolismo , Condrocitos/patología , MicroARNs/metabolismo , Osteoartritis/genética , Osteoartritis/patología , ARN Largo no Codificante/metabolismo , Supervivencia Celular , Células Cultivadas , Silenciador del Gen , Humanos , MicroARNs/genética , ARN Largo no Codificante/genética , Regulación hacia Arriba/genéticaRESUMEN
The present study focuses on the biological synthesis, characterization, and antibacterial activities of silver nanoparticles (AgNPs) using extracellular extracts of Aspergillus japonicus PJ01.The optimal conditions of the synthesis process were: 10 mL of extracellular extracts, 1 mL of AgNO3 (0.8 mol/L), 4 mL of NaOH solution (1.5 mol/L), 30 °C, and a reaction time of 1 min. The characterizations of AgNPs were tested by UV-visible spectrophotometry, zeta potential, scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric (TG) analyses. Fourier transform infrared spectroscopy (FTIR) analysis showed that Ag+ was reduced by the extracellular extracts, which consisted chiefly of soluble proteins and reducing sugars. In this work, AgNO3 concentration played an important role in the physicochemical properties and antibacterial properties of AgNPs. Under the AgNO3 concentration of 0.2 and 0.8 mol/L, the diameters of AgNPs were 3.8 ± 1.1 and 9.1 ± 2.9 nm, respectively. In addition, smaller-sized AgNPs showed higher antimicrobial properties, and the minimum inhibitory concentration (MIC) values against both E. coli and S. aureus were 0.32 mg/mL.
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Antibacterianos , Aspergillus/metabolismo , Tecnología Química Verde/métodos , Nanopartículas del Metal/química , Plata/química , Antibacterianos/química , Antibacterianos/farmacologíaRESUMEN
Glucose dehydrogenase (GDH) is a general tool for driving nicotinamide (NAD(P)H) regeneration in synthetic biochemistry. An increasing number of synthetic bioreactions are carried out in media containing high amounts of organic cosolvents or hydrophobic substrates/products, which often denature native enzymes, including those for cofactor regeneration. In this work, we attempted to improve the chemical stability of Bacillus megaterium GDH (BmGDHM0 ) in the presence of large amounts of 1-phenylethanol by directed evolution. Among the resulting mutants, BmGDHM6 (Q252L/E170K/S100P/K166R/V72I/K137R) exhibited a 9.2-fold increase in tolerance against 10 % (v/v) 1-phenylethanol. Moreover, BmGDHM6 was also more stable than BmGDHM0 when exposed to hydrophobic and enzyme-inactivating compounds such as acetophenone, ethyl 2-oxo-4-phenylbutyrate, and ethyl (R)-2-hydroxy-4-phenylbutyrate. Coupled with a Candida glabrata carbonyl reductase, BmGDHM6 was successfully used for the asymmetric reduction of deactivating ethyl 2-oxo-4-phenylbutyrate with total turnover number of 1800 for the nicotinamide cofactor, thus making it attractive for commercial application. Overall, the evolution of chemically robust GDH facilitates its wider use as a general tool for NAD(P)H regeneration in biocatalysis.
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Glucosa 1-Deshidrogenasa/metabolismo , Niacinamida/metabolismo , Bacillus megaterium/enzimología , Alcoholes Bencílicos/química , Alcoholes Bencílicos/metabolismo , Glucosa 1-Deshidrogenasa/química , Glucosa 1-Deshidrogenasa/genética , Estructura Molecular , Mutación , Niacinamida/química , Oxidación-Reducción , Fenilbutiratos/química , Fenilbutiratos/metabolismoRESUMEN
Herein, we reported a green biosynthesis method of copper nanoparticles (CuNPs) at microwave irradiation condition by using pectin as a stabilizer and ascorbic acid as a reducing agent. Under the optimum conditions, CuNPs1 and 2 were synthesized under microwave times 0 and 3 min, respectively. Transmission electron microscope and scanning electron microscope (SEM) tests showed that CuNPs1 and 2 had irregular polygon particles with average diameters of 61.9 ± 19.4 and 40.9 ± 13.6 nm, respectively. Zeta potentials of CuNPs1 and 2 were -45.2 and -48.7 mV, respectively. X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy techniques were used to characterize the properties of CuNPs. Furthermore, inhibition zone tests showed that CuNPs2 exhibited higher antimicrobial activities against Escherichia coli, Staphylococcus aureus, and Aspergillus japonicus than CuNPs1. The antibacterial activities were also studied by the bacterial growth kinetics in broth media, and CuNPs2 exhibited lower minimum bactericidal concentrations than CuNPs1.
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Antiinfecciosos/síntesis química , Cobre/química , Nanopartículas del Metal/química , Pruebas de Sensibilidad Microbiana , Pectinas/química , Antibacterianos/farmacología , Ácido Ascórbico , Aspergillus/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Tecnología Química Verde , Cinética , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Tamaño de la Partícula , Espectroscopía de Fotoelectrones , Espectroscopía Infrarroja por Transformada de Fourier , Staphylococcus aureus/efectos de los fármacos , Termogravimetría , Difracción de Rayos XRESUMEN
Ubiquitination signaling is the main pathway of protein degradation in eukaryotic cells. Ubiquitin-proteasome system degrades the ubiquitinated cytoplasmic proteins and lysosome pathway mainly degrades the ubiquitinated membrane proteins. Previous studies have shown that ubiquitination signaling plays a critical role in fatty acids synthesis. In the process of fatty acids import, disruption of ubiquitination could prevent the degradation of fatty acid transport proteins, thereby promoting fatty acids import and milk fat synthesis in bovine primary mammary epithelial cells. In this review, we summarize the signal transduction and regulation mechanism of ubiquitination signaling in milk fat synthesis, which may provide references and new ideas for future research on milk fat traits in dairy cows.
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Glándulas Mamarias Animales , Leche , Animales , Bovinos , Células Epiteliales , Ácidos Grasos/metabolismo , Femenino , Leche/metabolismo , UbiquitinaciónRESUMEN
The present study evaluated the protective effects of pseurotin A against inflammation and the destruction of cartilage in a rat model of rheumatoid arthritis (RA). RA was induced by intradermal injections of Freund's complete adjuvant (1 mg/mL), and the treatment with pseurotin A (50 and 100 mg/kg, p.o.) was administered over 1 week. The effects of pseurotin A were assessed by estimating hind paw volume (HPV) and determining the levels of inflammatory mediators in the serum and synovial fluid of collagen-induced arthritis (CIA)-induced RA rats. Western blot and histopathological assays were performed to assess changes in synovial tissues. Additionally, in vitro analyses of receptor activator of nuclear factor-kappa-Β ligand (RANKL)-stimulated RAW264.7 cells treated with pseurotin A at different concentrations (1, 10, and 100 µg/mL) were conducted to assess the effects of pseurotin A on apoptosis ratio, real-time polymerase chain reaction data, and tartrate-resistant acid phosphatase staining. Compared to the RA group, treatment with pseurotin A significantly decreased HPV and reduced the levels of inflammatory mediators in the synovial fluid and blood. Additionally, pseurotin A ameliorated the protein expressions of osteoprotegerin, nuclear factor of activated T-cells, nuclear factor-kappa beta (NF-κB), IκBα, extracellular signal regulated kinase, and P38 as well as histopathological changes in the synovial tissue of CIA-induced RA rats. The in vitro findings revealed that pseurotin A treatment did not alter the apoptosis ratio in RANKL-stimulated RAW264.7 cells but significantly reduced the mRNA expressions of calcitonin receptor, NF-κB, and matrix metallopeptidase-9. The present findings suggest that pseurotin A ameliorated the differentiation of osteoclasts and the destruction of cartilage in RA rats via regulation of the mitogen-activated protein kinase/RANKL/NF-kB pathway.
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Artritis Experimental/tratamiento farmacológico , Artritis Reumatoide/tratamiento farmacológico , Sustancias Protectoras/uso terapéutico , Pirrolidinonas/uso terapéutico , Animales , Artritis Experimental/inmunología , Artritis Experimental/patología , Artritis Experimental/prevención & control , Artritis Reumatoide/inmunología , Artritis Reumatoide/patología , Cartílago/efectos de los fármacos , Cartílago/patología , Diferenciación Celular/efectos de los fármacos , Citocinas/inmunología , Dinoprostona/inmunología , Modelos Animales de Enfermedad , Articulaciones/efectos de los fármacos , Articulaciones/patología , Masculino , Ratones , Proteínas Quinasas Activadas por Mitógenos/inmunología , Osteoclastos/efectos de los fármacos , Osteoprotegerina/inmunología , Sustancias Protectoras/farmacología , Pirrolidinonas/farmacología , Ligando RANK/inmunología , Células RAW 264.7 , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacosRESUMEN
A new high-throughput method for screening 2-deoxyribose-5-phosphate aldolase variants with a higher activity toward aldol reaction of unnatural aldehydes was established for the first time by coupling with an aldehyde dehydrogenase LeADH. The error-prone PCR and site-directed saturation mutagenesis libraries of aldolase LbDERA were constructed and screened using the high-throughput method. Two improved variants, LbDERAT29L and LbDERAF163Y, were identified and combined, giving a double mutant LbDERAT29L/F163Y which showed 7-fold higher activity than the native enzyme. The crystal structure of LbDERAT29L/163Y obtained by X-ray diffraction with 1.77 Å resolution revealed the structural changes responsible for the significant activity improvement.
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Aldehído Deshidrogenasa/síntesis química , Aldehído Deshidrogenasa/genética , Diseño de Fármacos , Ensayos Analíticos de Alto Rendimiento/métodos , Ingeniería de Proteínas , Aldehído Deshidrogenasa/ultraestructura , Sitios de Unión , Activación Enzimática , Unión Proteica , Conformación Proteica , Especificidad por SustratoRESUMEN
BACKGROUND: Standards in treatment of acute cholecystitis (AC) in the elderly and high-risk patients has not been established. Our study evaluated the efficacy and safety of B-mode ultrasound-guided percutaneous transhepatic gallbladder drainage (PTGD) in combination with laparoscopic cholecystectomy (LC) for acute cholecystitis (AC) in elderly and high-risk patients. METHODS: Our study enrolled 35 elderly and high-risk AC patients, hospitalized between January 2010 and April 2014 at the Wenzhou People's Hospital. The patients underwent B-mode ultrasound-guided PTGD and LC (PTGD + LC group). As controls, a separate group of 35 elderly and high-risk AC patients who underwent LC alone (LC group) during the same period at the same hospital were randomly selected from a pool of 186 such cases. The volume of bleeding, surgery time, postoperative length of stay, conversion rate to laparotomy and complication rates (bile leakage, bleeding, incisional hernia, incision infection, pulmonary infarction and respiratory failure) were recorded for each patient in the two groups. RESULTS: All patients in the PTGD + LC group successfully underwent PTGD. In the PTGD + LC group, abdominal pain in patients was relieved and leukocyte count, alkaline phosphatase level, total bilirubin and carbohydrate antigen 19-9 (CA19-9) decreased to normal range, and alanine aminotransferase and aspartate aminotransferase levels improved significantly within 72 h after treatment. All patients in the PTGD + LC group underwent LC within 6-10 weeks after PTGD. Our study revealed that PTGD + LC showed a significantly higher efficacy and safety compared to LC alone in AC treatment, as measured by the following parameters: duration of operation, postoperative length of hospital stay, volume of bleeding, conversion rate to laparotomy and complication rate (operation time of LC: 55.6 ± 23.3 min vs. 91.35 ± 25.1 min; hospitalized period after LC: 3.0 ± 1.3 d vs. 7.0 ± 1.7 d; intraoperative bleeding: 28.7 ± 15.2 ml vs. 60.38 ± 16.4 ml; conversion to laparotomy: 3 cases vs. 10 cases; complication: 3 cases vs. 8 cases; all P < 0.05 ). CONCLUSION: Our results suggest that B-mode ultrasound-guided PTGD in combination with LC is superior to LC alone for treatment of AC in elderly and high-risk patients, showing multiple advantages of minimal wounding, accelerated recovery, higher safety and efficacy, and fewer complications.
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Colecistectomía Laparoscópica/métodos , Colecistitis Aguda/cirugía , Drenaje/métodos , Ultrasonografía Intervencional/métodos , Anciano , Anciano de 80 o más Años , Pérdida de Sangre Quirúrgica/estadística & datos numéricos , Colecistectomía Laparoscópica/efectos adversos , Colecistitis Aguda/diagnóstico por imagen , Terapia Combinada , Conversión a Cirugía Abierta/estadística & datos numéricos , Drenaje/efectos adversos , Femenino , Vesícula Biliar/cirugía , Humanos , Laparotomía , Tiempo de Internación , Masculino , Tempo Operativo , Complicaciones Posoperatorias/epidemiología , Resultado del Tratamiento , Ultrasonografía Intervencional/efectos adversosRESUMEN
Nitric oxide (NO) is a stress-signaling molecule in plants that mediates a wide range of physiological processes and responses to metal toxicity. In this work, various NO modulators (NO donor: SNP; NO scavenger: cPTIO; NO synthase inhibitor: l-NAME; and SNP analogs: sodium nitrite/nitrate and sodium ferrocyanide) were investigated to determine the role of NO in Trifolium repens L. plants exposed to Cd. Cd (100µM) markedly reduced biomass, NO production and chlorophyll (Chl a, Chl b and total Chl) concentration but stimulated reactive oxygen species (ROS) and Cd accumulation in plants. SNP (50µM) substantially attenuated growth inhibition, reduced hydrogen peroxide (H2O2) and malonyldialdehyde (MDA) levels, stimulated ROS-scavenging enzymes/agents, and mitigated the H(+)-ATPase inhibition in proton pumps. Interestingly, SNP considerably up-regulated the levels of jasmonic acid (JA) and proline in plant tissues but down-regulated the levels of ethylene (ET) in both shoots and roots and the level of salicylic acid (SA) in roots only, which might be related to the elevated NO synthesis. Additionally, SNP (25-200µM) regulated mineral absorption and, particularly at 50µM, significantly enhanced the uptake of shoot magnesium (Mg) and copper (Cu) and of root calcium (Ca), Mg and iron (Fe). Nevertheless, the effects of SNP on plant growth were reversed by cPTIO and l-NAME, suggesting that the protective effect of SNP might be associated with NO synthesis in vivo. Moreover, SNP analogs did not display roles similar to that of SNP. These results indicated that NO depleted Cd toxicity by eliminating oxidative damage, enhancing minerals absorption, regulating proton pumps, and maintaining hormone equilibrium.
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Cadmio/toxicidad , Minerales/metabolismo , Óxido Nítrico/fisiología , Reguladores del Crecimiento de las Plantas/metabolismo , Bombas de Protones/fisiología , Trifolium/efectos de los fármacos , Adenosina Trifosfatasas/metabolismo , Análisis de Varianza , Antioxidantes/metabolismo , Cadmio/metabolismo , Clorofila/metabolismo , Peróxido de Hidrógeno/metabolismo , Malondialdehído/farmacología , Óxido Nítrico/metabolismo , Donantes de Óxido Nítrico/farmacología , Estrés Oxidativo/efectos de los fármacos , Raíces de Plantas/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Ácido Salicílico/farmacología , Trifolium/metabolismo , Trifolium/fisiologíaRESUMEN
A novel nonheme chloroperoxidase (RhEst1), with promiscuous esterase activity for enantioselective hydrolysis of ethyl (S)-2,2-dimethylcyclopropanecarboxylate, was identified from a shotgun library of Rhodococcus sp. strain ECU1013. RhEst1 was overexpressed in Escherichia coli BL21(DE3), purified to homogeneity, and functionally characterized. Fingerprinting analysis revealed that RhEst1 prefers para-nitrophenyl (pNP) esters of short-chain acyl groups. pNP esters with a cyclic acyl moiety, especially that with a cyclobutanyl group, were also substrates for RhEst1. The Km values for methyl 2,2-dimethylcyclopropanecarboxylate (DmCpCm) and ethyl 2,2-dimethylcyclopropane carboxylate (DmCpCe) were 0.25 and 0.43 mM, respectively. RhEst1 could serve as an efficient hydrolase for the bioproduction of optically pure (S)-2,2-dimethyl cyclopropane carboxylic acid (DmCpCa), which is an important chiral building block for cilastatin. As much as 0.5 M DmCpCe was enantioselectively hydrolyzed into (S)-DmCpCa, with a molar yield of 47.8% and an enantiomeric excess (ee) of 97.5%, indicating an extremely high enantioselectivity (E = 240) of this novel and unique biocatalyst for green manufacturing of highly valuable chiral chemicals.
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Cloruro Peroxidasa/aislamiento & purificación , Cloruro Peroxidasa/metabolismo , Cilastatina/metabolismo , Inhibidores de Proteasas/metabolismo , Rhodococcus/enzimología , Secuencia de Aminoácidos , Cloruro Peroxidasa/genética , Clonación Molecular , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Cinética , Datos de Secuencia Molecular , Filogenia , Rhodococcus/genética , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Especificidad por SustratoRESUMEN
Recombinant Escherichia coli cells expressing Alcaligenes sp. nitrilase were simply immobilized by direct cross-linking using glutaraldehyde. About 85 % of the total nitrilase activity was recovered under the optimal cross-linking conditions. The thermal stabilities of the cross-linked cells measured at 30, 40 and 50 °C were 4.5-, 5.3-, and 5.1-fold those of the free cells, respectively. The concentration of (R)-(-)-mandelic acid reached 280 mM after merely 2 h transformation with the immobilized cells using 300 mM mandelonitrile as substrate, affording an extremely high productivity of 510.7 g L(-1) d(-1). In addition, operational stability of the immobilized cells was obviously superior to that of free cells, without significant activity loss after 15 cycles of batch reactions or 8 cycles of repeated fed-batch reactions. Therefore, the easy preparation and robust characteristics of the immobilized biocatalyst make it a very promising biocatalyst for high-performance and low-cost production of optically pure (R)-(-)-mandelic acid.
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Alcaligenes/enzimología , Aminohidrolasas/química , Escherichia coli/metabolismo , Glutaral/química , Ácidos Mandélicos/química , Acetonitrilos/química , Catálisis , Reactivos de Enlaces Cruzados/química , Relación Dosis-Respuesta a Droga , Enzimas/química , Enzimas Inmovilizadas , Concentración de Iones de Hidrógeno , Hidrólisis , Temperatura , Factores de TiempoRESUMEN
BACKGROUND: Dodecanedioic acid (DDA), a typical medium-chain dicarboxylic fatty acid with widespread applications, has a great synthetic value and a huge industrial market demand. Currently, a sustainable, eco-friendly and efficient process is desired for dodecanedioic acid production. RESULTS: Herein, a multi-enzymatic cascade was designed and constructed for the production of DDA from linoleic acid based on the lipoxygenase pathway in plants. The cascade is composed of lipoxygenase, hydroperoxide lyase, aldehyde dehydrogenase, and unidentified double-bond reductase in E. coli for the main cascade reactions, as well as NADH oxidase for cofactor recycling. The four component enzymes involved in the cascade were co-expressed in E. coli, together with the endogenous double-bond reductase of E. coli. After optimizing the reaction conditions of the rate-limiting step, 43.8 g L- 1 d- 1 of DDA was obtained by a whole-cell one-pot process starting from renewable linoleic acid. CONCLUSIONS: Through engineering of the reaction system and co-expressing the component enzymes, a sustainable and eco-friendly DDA biosynthesis route was set up in E. coli, which afforded the highest space time yield for DDA production among the current artificial multi-enzymatic routes derived from the LOX-pathway, and the productivity achieved here ranks the second highest among the current research progress in DDA biosynthesis.
RESUMEN
A novel flame retardant containing Si, N, and S elements, ((2-(triethoxysilyl)ethyl)thio)ethan-1-amine hydrochloride (TETEA), was synthesized via a click reaction and characterized using nuclear magnetic resonance spectroscopy (NMR) and fourier transform infrared spectroscopy (FTIR). Subsequently, the flame-retardant cotton fabric was fabricated by sol-gel method. The results indicated that TETEA was successfully loaded on cotton fabric and formed a uniform protective layer on the surface of cotton fabric, exhibiting excellent flame retardancy. The flame-retardant cotton fabric achieved limiting oxygen index (LOI) of 28.3 % and passed vertical combustion test without after-flame or afterglow time at TETEA concentration of 500 g/L. Thermogravimetric analysis revealed that the residual carbon content of the flame-retardant cotton fabric was much higher than that of the control under air and N2 conditions. Besides, the flame-retardant cotton fabric was not ignited in cone calorimeter test with an external heat flux of 35 kW/m2. The peak heat release rate and the total heat release decreased from 133.4 kW/m2 to 25.8 kW/m2 and from 26.46 MJ/m2 to 17.96 MJ/m2, respectively. This phosphorus-free flame retardant offers a simplified synthesis process without adverse environmental impacts, opening up a new avenue for the development environmentally friendly flame retardants compared to traditional alternatives.
Asunto(s)
Celulosa , Fibra de Algodón , Retardadores de Llama , Retardadores de Llama/síntesis química , Retardadores de Llama/análisis , Fibra de Algodón/análisis , Celulosa/química , Celulosa/análogos & derivados , Nitrógeno/química , Silicio/química , Espectroscopía Infrarroja por Transformada de Fourier , Termogravimetría , Sustancias Macromoleculares/química , Sustancias Macromoleculares/síntesis químicaRESUMEN
BACKGROUND: To date, there is no effective treatment for Alzheimer's disease (AD), a progressive neurodegenerative disorder that is increasing in prevalence worldwide. The objective of this review was to summarize the core targets and signaling pathways involved in acupuncture treatment for AD. METHODS: We reviewed numerous signaling pathways, including mammalian target of rapamycin (mTOR), phosphatidylinositol 3-kinase-protein kinase B (PI3 K/Akt), adenosine monophosphate-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK), nuclear factor (NF)-kB, p53, Wnt, nitric oxide (NO), Janus kinase / signal transducer and activator of transcription (JAK/ STAT), RhoA/ROCK (Rho-associated protein kinase) and Ca2+/ calmodulin-dependent protein kinase II (CaMKII) / cyclic adenosine monophosphate-response element-binding protein (CREB). The relevant data were obtained from PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure (CNKI) and Wanfang databases. RESULTS: In summary, the effects of acupuncture are mediated by multiple targets and pathways. Furthermore, acupuncture can improve pathological changes associated with AD (such as abnormal deposition of amyloid (A)ß, tau hyperphosphorylation, synaptic dysfunction and neuronal apoptosis) through multiple signaling pathways. CONCLUSION: Overall, our findings provide a basis for future research into the effects of acupuncture on AD.