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1.
《Process Biochemistry》2010,45(8):1432-1436
In this paper, a two-step process for initial capture of plasmid DNA (pDNA) and partial removal of RNA using polyethylene glycol (PEG) and di-potassium hydrogen phosphate aqueous two-phase systems (ATPS) has been investigated. A Kühni-type ATPS extraction column was prepared with 50 ml (12% (w/w) PEG 1450, 12% (w/w) phosphate) of stationary phase and loaded with crude mobile phase (26% (w/w) PEG 1450, 4% (w/w) phosphate and 70% (w/w) lysate) at a flow rate of 6 ml min−1 at an impeller speed of 200 rpm. The experiment was terminated after 100 min, and after complete resettling of the phases, 45 ml of stationary phase was harvested. During a subsequent second extraction step contained 18% (w/w) PEG 300 and 14% (w/w) phosphate, a proportion of RNA, which was also concentrated during the column process, was removed. It was demonstrated that the recovery of pDNA in the second bottom phase was 89.4%, which was similar to the initial recovery after column extraction (92.1%).  相似文献   

2.
In an attempt to determine the relationship between the Epstein–Barr virus nuclear antigen-1 (EBNA-1) expression level and specific foreign protein productivity (qp), EBNA-1-amplifed HEK293 cells, which achieved a higher EBNA-1 expression level than that achieved by HEK293E cells, were established using dihydrofolate reductase (dhfr)-mediated gene amplification. Compared with a control culture in a null pool, Fc-fusion protein production by transient transfection in the EBNA-1-amplified pool showed a significant improvement. qp was linearly correlated with the EBNA-1 expression level in the transient transfection of EBNA-1-amplified clones, as indicated by the correlation coefficient (R2 = 0.7407). The Fc-fusion protein production and qp in a transient gene expression-based culture with EBNA-1-amplified HEK293 cells, E-amp-68, were approximately 2.0 and 3.2 times, respectively, higher than those in a culture with HEK293E cells. The increase in qp by EBNA-1 amplification mainly resulted from an enhancement in the amount of replicated DNA and level of mRNA expression but not an improved transfection efficiency. Taken together, it was found that EBNA-1 amplification could improve the therapeutic protein production in an HEK293 cell-based transient gene expression system.  相似文献   

3.
Cysteinyl leukotrienes (cys-LTs) cause bronchoconstriction in anaphylaxis and asthma. They are formed by 5-lipoxygenase (5-LOX) from arachidonic acid (AA) yielding the unstable leukotriene A4 (LTA4) that is subsequently conjugated with glutathione (GSH) by LTC4 synthase (LTC4S). Cys-LT receptor antagonists and LTC4S inhibitors have been developed, but only the former have reached the market. High structural homology to related enzymes and lack of convenient test systems due to instability of added LTA4 have hampered the development of LTC4S inhibitors. We present smart cell-free and cell-based assay systems based on in situ-generated LTA4 that allow studying LTC4S activity and investigating LTC4S inhibitors. Co-incubations of microsomes from HEK293 cells expressing LTC4S with isolated 5-LOX efficiently converted exogenous AA to LTC4 (~ 1.3 μg/200 μg protein). Stimulation of HEK293 cells co-expressing 5-LOX and LTC4S with Ca2 +-ionophore A23187 and 20 μM AA resulted in strong LTC4 formation (~ 250 ng/106 cells). MK-886, a well-known 5-LOX activating protein (FLAP) inhibitor that also acts on LTC4S, consistently inhibited LTC4 formation in all assay types (IC50 = 3.1–3.5 μM) and we successfully confirmed TK04a as potent LTC4S inhibitor in these assay systems (IC50 = 17 and 300 nM, respectively). We demonstrated transcellular LTC4 biosynthesis between neutrophils or 5-LOX-expressing HEK293 cells that produce LTA4 from AA and HEK293 cells expressing LTC4S that transform LTA4 to LTC4. In conclusion, our assay approaches are advantageous as the substrate LTA4 is generated in situ and are suitable for studying enzymatic functionality of LTC4S including site-directed mutations and evaluation of LTC4S inhibitors.  相似文献   

4.
One of the most attractive segments in food and cosmetic industries is that of natural pigments. Since some synthetic pigments have been reported to be hazardous for humans, natural pigments obtained through biotechnological processes represent an attractive alternative. Our research group has previously worked on the development of an aqueous two-phase system (ATPS)-based prototype process for the recovery of B-phycoerythrin (BPE), a natural high-value pigment obtained from Porphyridium cruentum. Detailed studies describing the scaling up of ATPS processes from bench scale to pilot plant facilities are not common. In this paper experiences derived from the scale-up of a previously developed process for production and recovery of highly purified (purity defined as the absorbance ratio A545/A280 > 4) BPE are described, where a scale-up factor of 850× was implemented. Characterization of cell disruption with a pilot-scale bead mill allowed efficient BPE release at 2900 rpm, 10% (w/v) sample load, 60% (v/v) bead load and 0.5 mm glass beads and 22 min of residence time with a yield of 1.35 mg BPE/g of wet biomass. BPE was recovered and purified using a strategy comprising isoelectric precipitation, aqueous two-phase fractionation and ultrafiltration. A 54% global BPE recovery yield, with final purity of 4.1, was achieved under optimal process conditions. Considering total costs for raw materials and energy expenditures for one batch, it was determined that the production cost of BPE was of $1.17 USD/mg, which is underneath the commercial price of a BPE standard (>$30 USD/mg).  相似文献   

5.
Mucopolysaccharidosis IVA (MPS IVA) is a lysosomal storage disease caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS) enzyme. Currently, specific therapies are not available for MPS IVA patients. In this study, a biologically active recombinant GALNS enzyme (rGALNS) produced in Escherichia coli was purified through a two-step chromatography process. The effect of temperature and pH on purified rGALNS stability was evaluated, as well as the stability in human serum. Finally, the uptake of rGALNS by HEK 293 cells and MPS IVA fibroblasts was evaluated. The use of a semi-continuous process allowed the production of an active extracellular rGALNS, which was used for protein purification. The purified rGALNS showed a specific activity of 0.29 U mg?1 and a production yield of 0.78 mg L?1. The rGALNS presented an optimal pH of 5.5 and was stable for 8 days at 4 °C. In human serum it was stable for up to 6 h. rGALNS was not taken up by the cultured cells, suggesting that N-linked oligosaccharides are not necessary for the production of an active enzyme or enzyme stability but for the cell uptake of protein. This study shows the first characterization of rGALNS produced by E. coli, and provides important information about purification, stability, and glycosylations effect for this type of enzymes.  相似文献   

6.
《Process Biochemistry》2014,49(2):335-346
Selective purification still poses a challenge in the downstream processing of biomolecules such as proteins and especially enzymes. In this study a polyethylene glycol 3000 (PEG 3000)–phosphate aqueous two-phase system at 25 °C and pH 7 was successfully used for laccase purification and separation. Initially, the effect of phase forming components on enzyme activities in homogenous systems was studied. In the course of the extraction experiments tie lines, enzyme source, initial enzyme activities, phase ratio and sodium chloride concentrations were varied and their influence on the activity partitioning was determined. Partitioning results were validated using clear-native-PAGE and isoelectric focusing. Based on these results, the separation of laccases from Trametes versicolor and Pleurotus sapidus was investigated using the principle of superposition. Sodium chloride was used to adjust laccase partitioning in the applied aqueous two-phase system (ATPS). Finally, two modes of operation are proposed depending on the aim of the purification task. One mode with 0.133 g g−1 of PEG3000, 0.063 g g−1 of phosphate and without sodium chloride separates P. sapidus laccases from T. versicolor laccases with clearance factors of 5.23 and 6.45, respectively. The other mode of operation with 0.124 g g−1 of PEG3000, 0.063 g g−1 of phosphate and 0.013 g g−1 of sodium chloride enables a partitioning of both laccases into the bottom phase of the ATPS resulting in a purification factor of 2.74 and 96% activity recovery.  相似文献   

7.
《Process Biochemistry》2010,45(12):1928-1936
Recycling aqueous two-phase systems (ATPS) are hopeful application techniques in bioseparation and biocatalysis engineering areas. In this study, two novel light-sensitive and reversible water-soluble copolymers were synthesized and used in recycling ATPS. Polymer PNBAC was polymerized by using N-isopropylacrylamide (NIPA), n-butylmethacrylate (BMA), acrylic acid (AA) and chlorophyllin sodium copper salt (CHL) as monomers. Copolymer PNDBC was synthesized by NIPA, 2-(dimethylamino) ethylmethacrylate (DMAEMA), BMA and CHL as monomers. The synthesis yields of two copolymers are 66.9% and 77.2%, respectively. It can be calculated from 1H NMR graph that the molar ratios of monomers in PNBAC (NIPA:BMA:AA:CHL) and PNDBC (NIPA:DMAEMA:BMA:CHL) was 82:4:1:10 and 16:4:3:1, respectively. They could be precipitated by laser irradiation in 488 nm with the least light density of 1.70 × 105 W/m2. The precipitate energy is 1.79 kJ and 3.52 kJ/g, respectively. Five batches of average recoveries of two copolymers in the ATPS are 96.6% and 97.4%. BSA and l-phenylalanine were partitioned in the novel PNDBC–PNBAC ATPS, and their partition coefficients were 2.1 and 0.52. By applying this ATPS to partition of penicillin, the best partition coefficient K is 4.25.  相似文献   

8.
Background aimsWe evaluated hematopoietic stem cells according to CD34 expression and aldehyde dehydrogenase (ALDH) activity in peripheral blood and apheresis product samples from patients after mobilization with granulocyte–colony-stimulating factor (G-CSF) alone or G-CSF after high-dose cyclophosphamide (4 g/m2 once daily, intravenously on day 1). We also investigated the relationship between the number of SSClo CD45dim CD34hi cells, SSClo ALDHbr cells and engraftment.MethodsThirty patients (20 males and 10 females), who were candidates for autologous peripheral blood stem cell transplantation, were included in the study. Cyclophosphamide + G-CSF was used for 17 and G-CSF alone for 24 mobilizations. Primary diagnoses were multiple myeloma (n% = 14), Hodgkin's lymphoma (n% = 7), non-Hodgkin's lymphoma (n% = 2), acute myloid leukemia (n% = 2), chronic lymphocytic leukemia (n% = 1) and germ cell testis tumor (n% = 1).ResultsNumbers of SSClo CD45dim CD34hi cells and SSClo ALDHbr cells were highly correlated in both peripheral blood and apheresis products (P < 0.001). We could not find a relationship between the transplanted SSClo CD45dim CD34hi cell dose or SSClo ALDHbr cell dose and platelet or neutrophil recovery. The optimal thresholds for SSClo CD45dim CD34hi cells were 5.40 × 106/kg for neutrophil recovery and 7.22 × 106/kg for platelet recovery. The optimal thresholds for SSClo ALDHbr cells were 6.53 × 106/kg for neutrophil recovery and 8.72 × 106/kg platelet recovery.ConclusionsAccording to our data, numbers of SSClo ALDHbr cells are in very good agreement with numbers of SSClo CD45dim CD34hi cells and can be a predictor of stem cell mobilization.  相似文献   

9.
《Process Biochemistry》2007,42(2):275-278
Gray mold caused by Botrytis cinerea is an important disease of strawberry. Clonostachys rosea is a mycoparasite of B. cinerea that reduces fruit losses when used as a biocontrol agent. Since spore production by C. rosea has not been optimized, we investigated factors affecting sporulation under aseptic conditions on white rice grains. The greatest spore production in glass flasks, 3.4 × 109 spores/g-dry-matter (gDM), occurred with an initial moisture content of 46% (w/w wet basis), inoculated with 1 × 106 spores/gDM and hand shaken every 15 days. However, a lower inoculum density (9 × 103 spores/gDM) and no shaking also gave acceptable sporulation. In plastic bags 1.1 × 108 spores/gDM were produced in 15 days, suggesting that larger scale production may be feasible: with this spore content, 24 m2 of incubator space would produce sufficient spores for the continued treatment of 1 ha of strawberry plants.  相似文献   

10.
A lead compound 1, which inhibits the catalytic activity of PTK6, was selected from a chemical library. Derivatives of compound 1 were synthesized and analyzed for inhibitory activity against PTK6 in vitro and at the cellular level. Selected compounds were analyzed for cytotoxicity in human foreskin fibroblasts using MTT assays and for selectivity towards PTK members in HEK 293 cells. Compounds 20 (in vitro IC50 = 0.12 μM) and 21 (in vitro IC50 = 0.52 μM) showed little cytotoxicity, excellent inhibition of PTK6 in vitro and at the cellular level, and selectivity for PTK6. Compounds 20 and 21 inhibited phosphorylation of specific PTK6 substrates in HEK293 cells. Thus, we have identified novel PTK6 inhibitors that may be used as treatments for PTK6-positive carcinomas, including breast cancer.  相似文献   

11.
S-licarbazepine was synthesized by asymmetric reduction of oxcarbazepine with CGMCC No. 2266. The optimum batch reduction conditions were found to consist of a reaction time of 36 h, temperature of 30 °C, and initial pH value of 7.0. The optimum concentration of the glucose co-substrate was found to be 0.3 mol L−1. The addition of glucose contributed to in situ regeneration of NADPH in cells and improved conversion. Conversion increased with the addition of more biomass and with a decrease in the initial concentration of substrate. Within the membrane reactor, a continuous reduction process was used to improve production efficiency and reduce the inhibition of high-concentration substrate upon reduction. The optimum flux was found to be 20 ml h−1. S-licarbazepine yield was 3.7678 mmol L−1 d−1 in continuous reduction over four days. The enantiometric excess of S-licarbazepine was 100% for both batch and continuous reduction processes.  相似文献   

12.
A mixed-gel of κ-carrageenan and gelatin was used in l-phenylalanine production. The mixed-gel, containing 87.5% κ-carrageenan and 12.5% gelatin [the total gel concentration was 4 wt%], showed the best performance and was selected for further study with Escherichia coli EP8-10. The optimum pH and temperature were 8.5 and 37 °C, respectively. The effects of trehalose and Mg2+ were studied in the mixed-gel immobilization. Their optimum concentrations were 5 × 10?2 and 2 × 10?3 mol/L, respectively. Under the optimal conditions, 98.3% of the phenylpyruvic acid (PPA) was converted to l-phenylalanine. The activity recovery of the transaminase enzyme in the mixed-gel immobilization was higher than that in single κ-carrageenan immobilization, which was 93.6%. The total PPA conversion rate was over 80% in all 15 batches, suggesting great sustainability in the mixed-gel immobilization. The maximum reaction rate (rmax) was calculated to be 4.75 × 10?2 mol/(L g h).  相似文献   

13.
《Process Biochemistry》2010,45(7):1082-1087
In the present research, the potential use of flexible disposable devices, specifically blood bags, for the fractionation of biological products using Aqueous Two-Phase Systems (ATPS) polymer–salt is studied and demonstrated. Purified human serum albumin (HSA) was used as model protein. Experiments were carried out on ATPS polyethylene glycol (PEG)–potassium phosphate constructed on rigid recipients (conical tubes) and flexible devices (blood bags). The device used for ATPS construction had no significant effect on HSA partition behavior. Protein partition towards the top phase was favored on systems constructed using PEG 1000 g/mol and TLL 45% (w/w), achieving up to 85% recovery. On the other hand a recovery of 92% was achieved at the bottom phase when PEG 3350 g/mol and TLL 25% (w/w) were used. Human serum was used as a complex sample on ATPS experiments. Selective fractionation of human serum proteins on ATPS constructed on flexible devices was achieved. ATPS constructed on blood bags required short equilibrium times (< 6 min), meaning it is feasible to use this approach on mass scale. The potential use of flexible disposable devices, for the fractionation of biological products using ATPS polymer–salt was demonstrated.  相似文献   

14.
15.
While cyst germination may be an important factor for the initiation of harmful/toxic blooms, assessments of the fluctuation in phytoplankton cyst germination, from bottom sediments to water columns, are rare in situ due to lack of technology that can detect germinated cells in natural bottom sediments. This study introduces a simple mesocosm method, modeled after previous in situ methods, to measure the germination of plankton resting stage cells. Using this method, seasonal changes in germination fluxes of toxic dinoflagellates resting cysts, specifically Alexandrium fundyense (A. tamarense species complex Group I) and A. pacificum (A. tamarense species complex Group IV), were investigated at a fixed station in Kesennuma Bay, northeast Japan, from April 2014 to April 2015. This investigation was conducted in addition to the typical samplings of seawater and bottom sediments to detect the dinoflagellates vegetative cells and resting cysts. Bloom occurrences of A. fundyense were observed June 2014 and February 2015 with maximum cell densities reaching 3.6 × 106 cells m−2 and 1.4 × 107 cells m−2, respectively. The maximum germination fluxes of A. fundyense cysts occurred in April 2014 and December 2014 and were 9.3 × 103 cells m−2 day−1 and 1.4 × 104 cells m−2 day−1, respectively. For A. pacificum, the highest cell density was 7.3 × 107 cells m−2 during the month of August, and the maximum germination fluxes occurred in July and August, reaching 5.8 × 102 cells m−2 day−1. Thus, this study revealed the seasonal dynamics of A. fundyense and A. pacificum cyst germination and their bloom occurrences in the water column. Blooms occurred one to two months after peak germination, which strongly suggests that both the formation of the initial population by cyst germination and its continuous growth in the water column most likely contributed to toxic bloom occurrences of A. fundyense and A. pacificum in the bay.  相似文献   

16.
A bionanocomposite was cast using ZnO nanoparticles stabilized by soluble starch (nano-ZnO) as filler in a glycerol plasticized-pea starch (GPS) matrix. According to the characterization of nano-ZnO particles by Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG) and transmission electron microscopy (TEM), ZnO nanoparitlces (70 wt%) were encapsulated by starch (30 wt%) in nano-ZnO particles of about 10 nm. In GPS/nano-ZnO nanocomposites, loading a low level of nano-ZnO particles improved the pasting viscosity, storage modulus, glass transition temperature and UV absorbance. When the nano-ZnO content varied from 0 to 4 wt%, the tensile yield strength and Young’s modulus increased from 3.94 to 10.80 MPa and from 49.80 to 137.00 MPa, respectively. The water vapor permeability decreased from 4.76 × 10?10 to 2.18 × 10?10 g m?1 s?1 Pa?1. The improvement in these properties may be attributed to the interaction between the nano-ZnO filler and GPS matrix.  相似文献   

17.
Physiological control of akinete formation and subsequent germination is likely to be important in understanding and predicting how natural populations of cyanobacteria respond to their environment. While previous research has indicated nutrient limitation may be important in akinete formation new results presented here indicate that in the toxic and bloom-forming species Anabaena circinalis there was a profound effect of spectral quality. Under 40 μmol photons m?2 s?1 photosynthetically active irradiance (PAR) of predominately red irradiance akinete production was maximal at 2.1 × 10?4 akinetes vegetative cell?1 d?1, some 3000 times greater than the 6.5 × 10?8 akinetes vegetative cell?1 d?1 observed under equivalent PAR but predominately blue light. For cells grown under a range of predominantly red, white and green irradiance even short exposures to blue light reduced akinete formation rates by a factor of ten relative to controls, indicating that exposure to blue light inhibits akinete formation. Germination of akinetes was not influenced by the irradiance under which akinetes were formed: 88 ± 4.1% (mean ± 1 S.D.) of akinetes germinated with no evidence of an effect on germination success due to their production under predominately red, white or green irradiance (germination of akinetes produced under blue light was not tested). Spectral quality had a significant impact on both vegetative cell and germling growth rates. The results indicate a significant reduction in the cellular differentiation of A. circinalis vegetative cells into akinetes that is mediated by blue light. In an ecological context the production of akinetes will be greater in environments with less blue light; potentially including those with slower flow, more stratification, less vertical mixing and more turbidity. The resulting spatial pattern of akinete production is likely to influence the location of akinetes in sediments and the development of subsequent blooms from excysting germlings.  相似文献   

18.
Low-molecular-weight hyaluronan (LMW-HA) has attracted much attention because of its many potential applications. Here, we efficiently produced specific LMW-HAs from sucrose in Bacillus subtilis. By coexpressing the identified committed genes (tuaD, gtaB, glmU, glmM, and glmS) and downregulating the glycolytic pathway, HA production was significantly increased from 1.01 g L−1 to 3.16 g L−1, with a molecular weight range of 1.40×106–1.83×106 Da. When leech hyaluronidase was actively expressed after N-terminal engineering (1.62×106 U mL−1), the production of HA was substantially increased from 5.96 g L−1 to 19.38 g L−1. The level of hyaluronidase was rationally regulated with a ribosome-binding site engineering strategy, allowing the production of LMW-HAs with a molecular weight range of 2.20×103–1.42×106 Da. Our results confirm that this strategy for the controllable expression of hyaluronidase, together with the optimization of the HA synthetic pathway, effectively produces specific LMW-HAs, and could also be used to produce other LMW polysaccharides.  相似文献   

19.
Reactive oxygen species (ROS) produced by NADPH oxidases play critical roles in plant environmental responses. Arabidopsis thaliana NADPH oxidase AtRbohF-mediated ROS-production is involved in abiotic stress responses. Because overproduction of ROS is highly toxic to cells, the activity of AtRbohF needs to be tightly regulated in response to diverse stimuli. The ROS-producing activity of AtRbohF is activated by Ca2 + and protein phosphorylation, but other regulatory factors for AtRbohF are mostly unknown. In this study, we screened for proteins that interact with the N-terminal cytosolic region of AtRbohF by a yeast two-hybrid screen, and isolated AtSRC2, an A. thaliana homolog of SRC2 (soybean gene regulated by cold-2). A co-immunoprecipitation assay revealed that AtSRC2 interacts with the N-terminal region of AtRbohF in plant cells. Intracellular localization of GFP-tagged AtSRC2 was partially overlapped with that of GFP-tagged AtRbohF at the cell periphery. Co-expression of AtSRC2 enhanced the Ca2 +-dependent ROS-producing activity of AtRbohF in HEK293T cells, but did not affect its phosphorylation-dependent activation. Low-temperature treatment induced expression of the AtSRC2 gene in Arabidopsis roots in proportion to levels of ROS production that was partially dependent on AtRbohF. Our findings suggest that AtSRC2 is a novel activator of Ca2 +-dependent AtRbohF-mediated ROS production and may play a role in cold responses.  相似文献   

20.
In this study, Nocardia lactamdurans NRRL 3802 was explored for the first time for production of cephamycin C by using solid-state fermentation. The effects of various substrates, moisture content, inoculum size, initial pH of culture medium, additional nitrogen source and amino acids were investigated for the maximum production of cephamycin C by N. lactamdurans NRRL 3802 in solid-state fermentation. Subsequently, selected fermentation parameters were further optimized by response surface methodology (RSM). The soybean flour as a substrate with moisture content of 65%, initial pH of culture medium of 6.5 and inoculum size of 109 CFU/ml (2 × 108 CFU/gds) at 28 ± 2 °C after 4 days gave maximum production of 15.75 ± 0.27 mg/gds of cephamycin C as compared to 8.37 ± 0.23 mg/gds before optimization. Effect of 1,3-diaminopropane on cephamycin C production was further studied, which further increased the yield to 27.64 ± 0.33 mg/gds.  相似文献   

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