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Synovial angiogenesis is a key player in the development of rheumatoid arthritis (RA), and anti-angiogenic therapy is considered a promising approach for treating RA. CPD-002 has demonstrated efficacy in suppressing tumor angiogenesis as a VEGFR2 inhibitor, but its specific impacts on RA synovial angiogenesis and possible anti-RA effects need further study. We examined the influences of CPD-002 on the migration and invasion of human umbilical vein endothelial cells (HUVECs) and its impacts on HUVECs' tube formation and vessel sprouting ex vivo. The therapeutic potential of CPD-002 in adjuvant-induced arthritis (AIA) rats and its suppression of synovial angiogenesis were examined. The involvement of the VEGFR2/PI3K/AKT pathway was assessed both in HUVECs and AIA rat synovium. Here, CPD-002 inhibited the migration and invasion of VEGF-stimulated HUVECs, decreased their chemotactic response to RA fibroblast-like synoviocyte-released chemoattractants, and exhibited anti-angiogenic effects in vitro and ex vivo. CPD-002's targeting of VEGFR2 was confirmed with molecular docking and cellular thermal shift assays, supported by the abolishment of CPD-002's effects upon using VEGFR2 siRNA. CPD-002 relieved paw swelling, arthritis index, joint damage, and synovial angiogenesis, indicating its anti-arthritic and anti-angiogenic effects in AIA rats. Moreover, the anti-inflammatory effects in vivo and in vitro of CPD-002 contributed to its anti-angiogenic effects. Mechanistically, CPD-002 hindered the activation of VEGFR2/PI3K/AKT pathway in VEGF-induced HUVECs and AIA rat synovium, as evidenced by reduced p-VEGFR2, p-PI3K, and p-AKT protein levels alongside elevated PTEN protein levels. Totally, CPD-002 showed anti-rheumatoid effects via attenuating angiogenesis through the inhibition of the VEGFR2/PI3K/AKT pathway.
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Artrite Reumatoide , Proteínas Proto-Oncogênicas c-akt , Ratos , Humanos , Animais , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Angiogênese , Simulação de Acoplamento Molecular , Movimento Celular , Transdução de Sinais , Artrite Reumatoide/metabolismo , Células Endoteliais da Veia Umbilical Humana , Inibidores da Angiogênese/farmacologia , Inibidores da Angiogênese/uso terapêutico , Proliferação de CélulasRESUMO
The key to the innovation of sodium-ion batteries (SIBs) is to find efficient sodium-storage electrode. Here, metal Mo doping of NiSe2 is proposed by modified electrospinning strategy followed by in situ conversion process. The Mo-NiSe2 anchoring on hollow carbon nanofibers (HCNFs) would make full use of the multi-channel HCNFs in the inner layer and the active sites of Mo-NiSe2 in the outer layer, which plays an important role in buffering the volume stress of Na+ (de)insertion and reducing the adsorption energy barrier of Na+. Innovatively, it is proposed to jointly regulate the SIBs performance of NiSe2 by both metal atom doping and interface effects, thereby adjusting the sodium ion adsorption barrier of NiSe2. The Mo-NiSe2@HCNFs exhibits remarkable performance in SIBs, demonstrating a high specific capacity of 396 mAh/g after 100 cycles at 1 A/g. Moreover, it maintains outstanding cycling stability, retaining 77.6 % of its capacity (211 mAh/g) even after 1000 cycles at 10 A/g. This comprehensive electrochemical performances are due to the structural stability and outstanding electronic conductance of the Mo-NiSe2@HCNFs, as evidenced by the diffusion analysis and ex situ charge-discharge process characterization. Furthermore, coupled with the Na3V2(PO4)2O2F cathodes, the full cell also achieves a high energy density of 123 Wh kg-1. The theoretical calculation of the hypervalent Mo doing further proves the benefit of its Na+ adsorption and denser conduction band distribution. This study provides a reference for the construction of transition metal selenide via doping and interface engineering in sodium storage.
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In recent years, environmental DNA (eDNA) has been widely used in aquatic biodiversity monitoring, and how to establish a river ecological health assessment method based on eDNA has become a hot topic. This study was intended to develop a molecular diatom index based on eDNA to indicate the ecological health status of rivers under the influence of human activities. Firstly, the diatom community composition and structural changes in the Shaying River basin in spring and autumn were monitored through eDNA, and the driving environmental factors of the diatom community were diagnosed. Further, four strategies (OTU-taxonomy, OTU-free, ASV-taxonomy, and ASV-free) based on eDNA metabarcoding data were compared, and a molecular diatom index suitable for ecological health assessment in the Shaying River basin was constructed. The results showed that: â there were seasonal differences in diatom community structure, and Discostella pseudostelligera, Nitzschia amphibia, Diatoma vulgaris, and other groups were the main factors to distinguish the seasonal differences. â¡ Mn, Fe, and TN were the main environmental factors affecting diatom community structure in spring, whereas COD and Cu were the main environmental factors affecting diatom community structure in autumn. ⢠Among the four strategies, the diatom index calculated based on OTU-free data better reflected the environmental gradient change; the diatom index showed that the ecological health status of the Shaying River Basin was better in autumn than that in spring in time and better in the upstream than that in the downstream in space. In conclusion, this study monitored diatom community in Shaying River in spring and autumn through eDNA and constructed the molecular diatom index in the Shaying River basin, which promoted the application of eDNA to evaluate river ecological health.
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DNA Ambiental , Diatomáceas , Humanos , Diatomáceas/genética , Monitoramento Ambiental/métodos , Biodiversidade , Rios , EcossistemaRESUMO
Therapeutic enzymes play important roles in modern medicine due to their high affinity and specificity. However, it is very expensive to use them in clinical medicine because of their low stability and bioavailability. To improve the stability and effectiveness of therapeutic enzymes, immobilization techniques have been employed to enhance the applications of therapeutic enzymes in the past few years. Reported immobilization techniques include entrapment, adsorption, and covalent attachment. In addition, protein engineering is often used to improve enzyme properties; however, all methods present certain advantages and limitations. For carrier-bound immobilization, the delivery and release of the immobilized enzyme depend on the properties of the carrier and enzyme. In this review, we summarize the advantages and challenges of the current strategies developed to deliver therapeutic enzymes and provide a future perspective on the immobilization technologies used for therapeutic enzyme delivery.
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Sodium-ion batteries (SIBs) have aroused great attention because of the low cost and environmental benignity of sodium resources. However, practical applications of SIBs are plagued by the sluggish kinetics of sodium ions with large size in the host structure, which results in poor rate performance and rapid capacity decline. Herein, a self-templated approach was developed to synthesize MoS2 /Cu2 Se nanosheets with improved interfacial electron- and ion-transfer kinetics. The MoS2 /Cu2 Se nanosheets provided superior sodium storage performance, delivering 139â mAh g-1 at a high current density of 100â A g-1 and 222â mAh g-1 after 14000 cycles (at 20â A g-1 ). The outstanding electrochemical performance was attributed to the synergetic engineering of interface and structure, which could enhance the electrochemical kinetics and gave excellent mechanical properties to deal with the volume expansion phenomenon. Combined with a high-voltage cathode, the full battery demonstrated a high energy density of 152â Wh kg-1 at a power density of 420â W kg-1 , which opens a new avenue for the development of high-performance SIBs.
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Environmental DNA (eDNA) metabarcoding provides a fast and efficient way to obtain biodiversity information that has been widely used in aquatic biodiversity monitoring and assessment. To facilitate the application of eDNA metabarcoding in China, the accuracy of metabarcoding data needs to be further assessed. Here, the eukaryotic phytoplankton in Dianchi Lake and the northern portion of Fuxian Lake were examined. The effect of sequencing depth on species diversity was also explored, and accuracy was evaluated by comparing the taxon overlap and coefficient of variation (CV) of the α diversity index among biological replicates. The results showed that:â Sequencing depth significantly affected the taxon number and accuracy of alpha diversity determinations. The suggested sequencing depth for metabarcoding of eukaryotic phytoplankton in Dianchi Lake and Fuxian Lake is at least 30000. â¡ The OTU overlap was 45.97%±1.67% among three biological replicates, the genera overlap was 64.21%±3.25%, and the CV of alpha diversity was less than 10%. ⢠Seventy-five and 90 genera of eukaryotic algae were identified in Dianchi Lake and Fuxian Lake, respectively, covering 62.5% and 71.05% of the morphologically detected species, respectively. ⣠There was no significant variation in the diversity of eukaryotic algae with depth in Dianchi Lake, while diversity showed significant vertical patterns in Fuxian Lake. Overall, eukaryotic algal diversity was significantly lower in Dianchi Lake compared to Fuxian Lake, and diversity in the southern portion of Dianchi Lake was significantly higher than that in the central and northern portions (P<0.05). Our study demonstrates the feasibility and accuracy of using eDNA-based techniques to monitor eukaryotic phytoplankton diversity, which supports the widespread application of eDNA metabarcoding in China.
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Lagos , Fitoplâncton , Biodiversidade , China , Código de Barras de DNA Taxonômico , Monitoramento Ambiental , Eucariotos/genética , Fitoplâncton/genética , TecnologiaRESUMO
L-Tagatose, a promising building block in the production of many value-added chemicals, is generally produced by chemical routes with a low yield, which may not meet the increasing demands. Synthesis of l-tagatose by enzymatic oxidation of d-galactitol has not been applied on an industrial scale because of the high cofactor costs and the lack of efficient cofactor regeneration methods. In this work, an efficient and environmentally friendly enzymatic method containing a galactitol dehydrogenase for d-galactitol oxidation and a water-forming NADH oxidase for regeneration of NAD+ was first designed and used for l-tagatose production. Supplied with only 3 mM NAD+, subsequent reaction optimization facilitated the efficient transformation of 100 mM of d-galactitol into l-tagatose with a yield of 90.2 % after 12 h (obtained productivity: 7.61 mM.h-1). Compared with the current chemical and biocatalytic methods, the strategy developed avoids by-product formation and achieves the highest yield of l-tagatose with low costs. It is expected to become a cleaner and more promising route for industrial biosynthesis of l-tagatose.
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Hexoses/biossíntese , Complexos Multienzimáticos/metabolismo , NADH NADPH Oxirredutases/metabolismo , Desidrogenase do Álcool de Açúcar/metabolismo , Hexoses/química , Concentração de Íons de Hidrogênio , Modelos Moleculares , Conformação Molecular , TemperaturaRESUMO
The development of metal-organic frameworks (MOFs) as high-efficiency electrocatalysts for water splitting has attracted special attention due to their unique structural features including high porosity, large surface areas, high concentrations of active sites, uniform pore sizes and shapes, etc. Most of the related reports focus on the in situ generation of high-efficiency electrocatalysts by annealed MOFs. However, the pyrolysis process usually destroys the porous structure of MOFs and reduces the number of active sites due to the absence of organic ligands and agglomeration of metal centers. In this work, we prepared unique NiCo-MOF hollow nanospheres (NiCo-MOF HNSs) by a solvothermal method and further fabricated Fe-doped NiCo-MOF HNSs (Fe@NiCo-MOF HNSs) by a simple impregnation-drying method. Significant enhancement of electrocatalytic activity of Fe@NiCo-MOF HNSs was witnessed because of the doped Fe. Compared with the parent NiCo-MOF HNSs, the optimized Fe@NiCo-MOF HNSs exhibited a lower overpotential of 244 mV at 10 mA·cm-2 with a smaller Tafel slope of 48.61 mV·dec-1, which was lowered by ca. 90 mV due to the influence of Fe doping on the electronic structure of the active centers of Ni and Co. The above materials also displayed excellent stability without obvious activity decay for at least 16 hours. These findings present a new entry in the design and fabrication of high-efficiency MOF-based electrocatalysts for energy conversion.
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Pristine metal-organic frameworks (MOFs) have received much attention in recent years due to their high specific surface areas, large porosity, excellent pore size distributions, flexible structure, and remarkable catalytic properties. The design of functional MOFs that can function as efficient HER and OER catalysts is significant in solving the energy crisis but remains a big challenge. Tri-metallic metal-organic frameworks show a good application prospect in water oxidation. In this review, we are going to focus on the latest progress and future trends in the development of pristine trimetallic MOFs with respect to the OER. The synergistic effect between multi-metal active sites is effective at improving the intrinsic activity of MOFs toward the OER. By summarizing the synthesis method of tri-metallic MOFs and observing their performance toward the oxygen evolution reaction, we hope that this review will trigger new developments in coordination chemistry, electrochemistry, nanomaterials and energy materials.
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Enzyme-catalyzed cofactor regeneration is a significant approach to avoid large quantities consumption of oxidized cofactor, which is vital in a variety of bioconversion reactions. NADH: FMN oxidoreductase is an ideal regenerating enzyme because innocuous molecular oxygen is required as an oxidant. But the by-product H2O2 limits its further applications at the industrial scale. Here, novel NADH: FMN oxidoreductase (LrFOR) from Lactobacillus rhamnosus comprised of 1146 bp with a predicted molecular weight of 42â¯kDa was cloned and overexpressed in Escherichia coli BL21 (DE3). Enzyme assay shows that the purified recombinant LrFOR has both the NADPH and NADH oxidation activity. Biochemical characterizations suggested that LrFOR exhibits the specific activity of 39.8 U·mg-1 with the optimal pH and temperature of 5.6 and 35⯰C and produces H2O instead of potentially harmful peroxide. To further study its catalytic function, a critical Thr29 residue and its six mutants were investigated. Mutants T29G, T29A, and T29D show notable enhancement in activities compared with the wild type. Molecular docking of NADH into wild type and its mutants reveal that a small size or electronegative of residue in position29 could shorten the distance of NADH and FMN, promoting the electrons transfer and resulting in the increased activity. This work reveals the pivotal role of position 29 in the catalytic function of LrFOR and provides effective catalysts in NAD+ regeneration.
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FMN Redutase/genética , FMN Redutase/metabolismo , Lacticaseibacillus rhamnosus/enzimologia , NAD/metabolismo , Água/metabolismo , Catálise , Clonagem Molecular , Escherichia coli/genética , Peróxido de Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Lacticaseibacillus rhamnosus/genética , Simulação de Acoplamento Molecular , Mutação , OxirreduçãoRESUMO
As an important two-dimensional material, layered double hydroxides (LDHs) show considerable potential in electrocatalytic reactions. However, the great thickness of the bulk LDH materials significantly limits their catalytic activity. In this work, we report ultrathin NiFe-LDH nanosheets with sulfate interlayer anions (Ni6Fe2(SO4)(OH)16·7H2O) (U-LDH(SO4 2-)), which can be synthesized in gram-scale by a simple solvothermal method. The U-LDH(SO4 2-) shows excellent stability and great electrocatalytic performance in OER with a current density of 10 mA cm-2 at a low overpotential of 212 mV and a small Tafel slope of 65.2 mV dec-1, exhibiting its great potential for a highly efficient OER electrocatalyst.
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Cofactor regeneration is an important method to avoid the consumption of large quantities of oxidized cofactor NAD+ in enzyme-catalyzed reactions. Herein, glycerol dehydrogenase (GDH) and NADH oxidase preparations by aggregating enzymes with ammonium sulphate followed by cross-linking formed aggregates for effective regeneration of NAD+. After optimization, the activity of combi-CLEAs and separate CLEAs mixtures were 950 and 580 U/g, respectively. And the catalytic stability of combi-CLEAs against pH and temperature was superior to the free enzyme mixture. After ten cycles of reuse, the catalytic efficiency could still retain 63.3% of its initial activity, indicating that the constructed combi-CLEAs system had excellent reusability. Also, the conversion of glycerol to 1,3-dihydroxyacetone (DHA) was improved by the constructed NAD+ regeneration system, resulting in 4.6%, which was 2.5 times of the free enzyme system. Thus, wide applications of this co-immobilization method in the production of various chiral chemicals could be expected in the industry for its high efficiency at a low cost.
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Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Complexos Multienzimáticos/química , Complexos Multienzimáticos/metabolismo , NADH NADPH Oxirredutases/química , NADH NADPH Oxirredutases/metabolismo , NAD/metabolismo , Desidrogenase do Álcool de Açúcar/química , Desidrogenase do Álcool de Açúcar/metabolismo , Biocatálise , Coenzimas/metabolismo , Di-Hidroxiacetona/metabolismo , Estabilidade EnzimáticaRESUMO
Design and synthesis of non-noble metal electrocatalysts with high activity and durability for the electrolysis of water is of great significance for energy conversion and storage. In this work, we prepared a series of Fe-doped MoS2 nanomaterials by simple one-pot solvothermal reactions of (NH4)2MoS4 with FeCl3·6H2O. An optimized working electrode of Fe-MoS2-5 displayed high hydrogen evolution reaction (HER) activity with a relatively small overpotential of 173 mV to achieve a current density of 10 mA cm-2 in 0.5 M H2SO4, along with no significant change in catalytic performance even after 1000 cyclic voltammetry (CV) cycles. Fe-MoS2 nanoparticles on nickel foam (NF; denoted as Fe-MoS2/NF) exhibited an overpotential of 230 mV at 20 mA cm-2 for the oxygen evolution reaction (OER) and 153 mV at 10 mA cm-2 for the HER in 1.0 M KOH electrolyte. Fe-MoS2/NF was stable for more than 140 h under these conditions. Furthermore, the two electrode system of Fe-MoS2/NF (anode)//Fe-MoS2/NF (cathode) electrodes demonstrated excellent electrocatalytic activity toward overall water splitting with a low potential of 1.52 V at 10 mA cm-2 in 1.0 M KOH electrolyte.
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The development of bifunctional non-noble metal electrocatalysts demonstrating high activity and stability for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for renewable and clean energy. In this work, we report hierarchically structured integrated Fe-MoS2/Ni3S2/NF (NF = nickel foam) materials prepared by a facile in situ solvothermal method, and among them, the Fe-doped MoS2 was assembled into spine-like nanorods. The optimized electrocatalyst (denoted as Fe-MoS2/Ni3S2/NF-2) demonstrated excellent activity and durability for performing the HER and OER in an alkaline electrolyte (pH = 14) with low overpotentials of 130.6 mV and 256 mV (vs. RHE) at a current density of 10 mA cm-2, as well as no significant loss in catalytic performance even after 2000 cyclic voltammetry (CV) cycles. An outstanding durability of 180 h could be achieved for OER. The overall water splitting made up of the two-electrode system with Fe-MoS2/Ni3S2/NF-2 as both the anode and the cathode required a voltage of only 1.61 V to drive a current density of 10 mA cm-2 along with an outstanding long-term stability of 20 h, displaying its great potential for application in water splitting. The effective construction of multi-component synergistic structures shows a good pathway for high-performance electrocatalysis and energy storage.
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Objective: This study aimed to establish a simplified T classification based on the 8th edition of the Union for International Cancer Control/American Joint Committee on Cancer (UICC/AJCC) staging system for nasopharyngeal carcinoma (NPC). Methods: In total, 325 patients with NPC were included in this study. All patients underwent magnetic resonance imaging, and the staging criteria were recorded. These patients were subjected to staging with the 8th edition of the UICC/AJCC staging system for NPC. Results: Involvement of the oropharynx, nasal cavity, adjacent soft tissue (medial pterygoid, lateral pterygoid, and prevertebral muscles), cervical vertebra, orbit, and hypopharynx were always accompanied by other equivalently or more advanced T-stage classifications. All cases with involvement of the paranasal sinuses showed skull base erosion. The majority of cases with involvement of the pterygoid structure showed skull base erosion. Conclusion: According to the simplification principle, the following new T classification based on the 8th edition of the UICC/AJCC staging system was established: T1, tumor confined to nasopharynx, or beyond the nasopharynx without parapharyngeal involvement; T2, tumor with extension to the parapharyngeal space; T3, tumor with infiltration to bony structures at the skull base; T4, tumor with intracranial extension, involvement of the cranial nerves or parotid gland, and/or extensive soft tissue infiltration beyond the lateral surface of the lateral pterygoid muscle. Validation with a large series of patients is needed.
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Enzymatic NADP+ regeneration is a promising approach to produce valuable chemicals under economic conditions. Among all the enzymatic routes, using water-forming NADH oxidase is an ideal one because there is no by-product. However, most NADH oxidases have a low specific activity to NADPH. In this work, a thermostable NADH oxidase from Lactobacillus rhamnosus (LrNox) was rationally engineered to switch its specificity from NADH to NADPH. The results show that mutants D177A, G178R, D177A/G178R, D177A/G178R/L179S improved the NADPH activity by a factor of 4-6. The highest NADPH catalytic efficiency (Kcat/Km 223.71â¯S-1⯵m-1, 47.6-fold higher than wild-type LrNox) and 51% of NADH activity retention were achieved by replacing the single amino acid Leu179 for serine (L179S) in LrNox. Modeling of L179S-NADPH complex reveals that the phosphate group of NADPH interacts with the hydroxyl of Ser179 with a strong hydrogen bond and several shorter hydrogen bonds with the amino group of Lys185 could stabilize the binding of NADPH in the L179S mutant. This work provides an efficient method for converting NAD(P)H specificity and shows that L179S mutant is a potential and efficient auxiliary enzyme for NADP+ regeneration.
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Lacticaseibacillus rhamnosus/enzimologia , Lacticaseibacillus rhamnosus/genética , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Mutação , NADH NADPH Oxirredutases/genética , NADH NADPH Oxirredutases/metabolismo , NADP/metabolismo , NAD/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Ativação Enzimática , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Complexos Multienzimáticos/química , NAD/química , NADH NADPH Oxirredutases/química , NADP/química , Ligação Proteica , Análise Espectral , Relação Estrutura-Atividade , Especificidade por SubstratoRESUMO
Ultrathin metal-organic framework (MOF) nanosheets (NSs) offer potential for many applications, but the synthetic strategies are largely limited to top-down, low-yield exfoliation methods. Herein, Ni-M-MOF (M=Fe, Al, Co, Mn, Zn, and Cd) NSs are reported with a thickness of only several atomic layers, prepared by a large-scale, bottom-up solvothermal method. The solvent mixture of N,N-dimethylacetamide and water plays key role in controlling the formation of these two-dimensional MOF NSs. The MOF NSs can be directly used as efficient electrocatalysts for the oxygen evolution reaction, in which the Ni-Fe-MOF NSs deliver a current density of 10â mA cm-2 at a low overpotential of 221â mV with a small Tafel slope of 56.0â mV dec-1 , and exhibit excellent stability for at least 20â h without obvious activity decay. Density functional theory calculations on the energy barriers for OER occurring at different metal sites confirm that Fe is the active site for OER at Ni-Fe-MOF NSs.
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Cysteine, a critical residue for catalytic process but also vulnerable to oxidative damage, was conventionally expressed as a buried catalytic site in most redox enzymes. In the present work, specific surface-exposed sites of a NADH oxidase from Lactobacillus rhamnosus (LrNox) were selected and mutated to cysteine to investigate its effects on catalytic function because LrNox has a buried catalytic cysteine but no surface-exposed one. The results showed that exception of the sites on dimer interface, the activities of LrNox mutants were improved to vary degrees when the polar uncharged and alanine residues were mutated to cysteine. But the cysteine mutations of polar charged and nonpolar residues except alanine showed obvious decline in catalytic activity. Substituting of Ala85 and Thr96 with other residues suggested that the cysteine mutation showed the highest activity. Structural analysis suggested that even a single cysteine mutation on the specific non-conserved surface area of LrNox could induce changes on the conformation of catalytic cysteine and lower the activation free energy to improve the catalytic activity.
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Cisteína/metabolismo , Lacticaseibacillus rhamnosus/enzimologia , Complexos Multienzimáticos/química , Complexos Multienzimáticos/metabolismo , NADH NADPH Oxirredutases/química , NADH NADPH Oxirredutases/metabolismo , Biocatálise , Cinética , Simulação de Acoplamento Molecular , Complexos Multienzimáticos/genética , Mutagênese Sítio-Dirigida , Mutação , NADH NADPH Oxirredutases/genética , Estrutura Secundária de Proteína , Propriedades de SuperfícieRESUMO
A novel nicotinamide adenine dinucleotide (NADH) oxidase from Streptococcus mutans ATCC 25175 (SmNox) was cloned and overexpressed in Escherichia coli BL21 (DE3). Sequence analysis revealed an open reading frame of 1374bp, capable of encoding a polypeptide of 457 amino acid residues. The molecular mass of the purified SmNox was estimated to be â¼49.9kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified SmNox had the highest specific activity of 281.2U·mg-1 at optimal pH and temperature of 7.0 and 35°C, with a Km of 57.7µM and a Vmax of 154.3U·mg-1. The good stability at room temperature was observed. Homology modeling and substrate docking were performed to evaluate the catalytic characteristics. The results indicated that Nicotinamide ring of NADH extends vertically toward to re-face of coenzyme (FAD), and the specific conformation of NADH suggested that the charges transfer in SmNox complex could be easier than in its homologous enzyme (LbNox) under alkaline environment. The characterization of the SmNox indicated it has potential in industrial regeneration of coenzyme NAD+ for coupling with dehydrogenases.
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Modelos Moleculares , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , NADH NADPH Oxirredutases/genética , NADH NADPH Oxirredutases/metabolismo , Homologia de Sequência de Aminoácidos , Streptococcus mutans/enzimologia , Streptococcus mutans/genética , Água/metabolismo , Biocatálise , Clonagem Molecular , Estabilidade Enzimática , Flavina-Adenina Dinucleotídeo/metabolismo , Expressão Gênica , Concentração de Íons de Hidrogênio , Cinética , Metais/farmacologia , Simulação de Acoplamento Molecular , Complexos Multienzimáticos/química , NADH NADPH Oxirredutases/química , Conformação Proteica , TemperaturaRESUMO
Metal-organic frameworks (MOFs) are a class of promising materials for diverse heterogeneous catalysis, but they are usually not directly employed for oxygen evolution electrocatalysis. Most reports focus on using MOFs as templates to inâ situ create efficient electrocatalysts through annealing. Herein, we prepared a series of Fe/Ni-based trimetallic MOFs (Fe/Ni/Co(Mn)-MIL-53 accordingly to the Material of Institute Lavoisier) by solvothermal synthesis, which can be directly adopted as highly efficient electrocatalysts. The Fe/Ni/Co(Mn)-MIL-53 shows a volcano-type oxygen evolution reaction (OER) activity as a function of compositions. The optimized Fe/Ni2.4 /Co0.4 -MIL-53 can reach a current density of 20â mA cm-2 at low overpotential of 236â mV with a small Tafel slope of 52.2â mV dec-1 . In addition, the OER performance of these MOFs can be further enhanced by directly being grown on nickel foam (NF).