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  • Artikel  (31)
  • immobilization  (31)
  • Wiley-Blackwell  (31)
  • American Chemical Society
  • American Institute of Physics (AIP)
  • 1990-1994  (31)
  • 1945-1949
  • 1940-1944
  • Werkstoffwissenschaften, Fertigungsverfahren, Fertigung  (31)
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  • Artikel  (31)
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  • Wiley-Blackwell  (31)
  • American Chemical Society
  • American Institute of Physics (AIP)
  • Springer  (12)
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  • 1990-1994  (31)
  • 1945-1949
  • 1940-1944
  • 1995-1999  (29)
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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 321-330 
    ISSN: 0006-3592
    Schlagwort(e): crystalline surface layers ; Protein A ; immobilization ; affinity matrix ; Clostridium thermohydrosulfuricum ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In this article, we describe a novel type of affinity matrix which was prepared by covalently binding Protein A to crystalline cell surface layers (S-layers) from the gram-positive Clostridium thermohydrosulfuricum L111-69. S-layers were used in the form of cell wall fragments, which were obtained by breaking whole cells by ultrasonification and removing the cell content and the plasma membrane. In these thimble shaped structures, revealing a size of 1 to 2 μm, the peptidoglycan-containing layer was covered on both faces with a hexagonally ordered S-layer lattice composed of identical glycoprotein subunits. After crosslinking the S-layer protein with glutaraldehyde, carboxyl groups from acidic amino acids were activated with carbodiimide and used for immobilization of Protein A. Quantitative determination confirmed that up to two Protein A molecules were bound per S-layer subunit leading to a dense monomolecular coverage of the immobilization matrix with the ligand.Affinity microparticles were capable of adsorbing lgG from solutions of purified preparations, from artificial lgG-albumin mixtures, and from serum. The amount of lgG bound to affinity microparticles corresponded to the theoretical saturation capacity. Under appropriate conditions, up to 95% of the adsorbed lgG could be eluted again. Affinity microparticles were found to have an extremely low Protein A leakage and a high stability toward mechanical forces. Because pores in the S-layer lattice revealed a size of 4 to 5 nm, immobilization of Protein A and adsorption of lgG was restricted to the outermost surface area. This excludes mass transfer problems usually encountered with affinity matrices prepared from amorphous polymers where more than 90% of the ligands are immobilized in the interior. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 934-938 
    ISSN: 0006-3592
    Schlagwort(e): immobilization ; nonaqueous enzymology ; esterification ; Rhizomucor miehei lipase ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: For the commercial exploitation of lipase biocatalysis to be successful, it is essential that effective supports are selected for lipase immobilization. In this study hydrophobic controlled-pore glasses have been used as model systems for the immobilization of Rhizomucor miehei lipase. The effect of pore diameter and surface chemistry on enzyme efficiency in a typical esterification reaction under essentially nonaqueous conditions has been examined. It has been found that pore diameters of at least 35 nm are needed for the lipase to be able to utilize the internal volume of the support particles in the immobilization process. Despite the small size of the substrates in the esterification reaction, even larger pores (〉100 nm) are required for the lipase efficiency to become independent of pore diameter; below 100 nm lipase activity and efficiency are markedly reduced. It has also been shown that the chemical nature of the hydrophobic surface plays an important part in catalyst design. Although lipase will adsorb readily to a wide range of hydrophobic groups, the highest catalyst activities are obtained when the glass surface is derivatized to give long alkyl chains; the presence of unsaturated derivatives gonerally leads to a reduction in activity. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 635-644 
    ISSN: 0006-3592
    Schlagwort(e): hepatocytes ; artificial liver ; long-term culture ; packed-bed reactor ; porous resin ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: As part of our attempt to develop a hybrid artificial liver support system using cultured hepatocytes, we investigated the long-term metabolic function of hepatocytes incubated in a packed-bed type reactor using reticulated polyvinyl formal (PVF) resin as a supporting material. Long-term (up to 1 week) perfusion culture experiments using the packed-bed reactor (20 mm i.d.) loaded with 500 PVF resin cubes (mean pore size 250 μm, 2 × 2 × 2 mm), together with conventional monolayer culture experiments as controls, were performed in serum-free or serum-containing medium. Ammonium metabolism and urea synthesis activities were evaluated quantitatively based on reaction kinetic analyses. Initial rates of ammonium metabolism and urea-N synthesis, as well as GPT enzyme activities, were adopted as indexes of the metabolic performance of the reactor and activities of the cultured hepatocytes.When serum-free medium was used in the perfusion cultures, ammonium metabolic and urea-N synthetic rates showed significant decay with elapse of the culture period, being less than 10% of those measured on day 1. This loss of activity was more prominent in the perfusion culture than in the monolayer cultures using this medium. In contrast, when serum-containing medium was used, approximately 50% of these activities obtained on day 1 were maintained even at the end of the cultures both in the perfusion and monolayer culture experiments.We concluded that the packed-bed reactor using PVF resin enabled high-density culture of hepatocytes, and showed a satisfactory ability to maintain the metabolic function of immobilized hepatocytes for relatively long periods of up to 1 week. This type of reactor is thus considered to represent a breakthrough in overcoming the difficulties involved in the development of a hybridtype artificial liver support system. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 79-86 
    ISSN: 0006-3592
    Schlagwort(e): lignin peroxidase ; Phanerochaete chrysosporium ; white-rot-fungus ; polymers ; immobilization ; 2-chilorophenol ; biodegradation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Porous poly(styrene-divinylbenzene) carriers, for the immobilization of white rot fungus Phanerochaete chrysosporium have been prepared by the concentrated emulsion polymerization method. The concentrated emulsion consists of a mixture of styrene and divinylbenzene containing a suitable surfactant and an initiator as the continuous phase, and water as the dispersed phase. The polymerization of the monomers of the continuous phase generated the polymer carrier with a porcus structure. The white rot fungus Phanerochaete chrysosporium has been immobilized on porous poly(styrene-divinylbenzene) carriers and used for the batch production and the repeated batch production of lignin peroxidase in shake cultures based on a carbon-limited medium containing veratryl alcohol. The best results were achieved when a spore inoculum was used for immobilization instead of 1-day-old mycelial pellets, for both the batch production and the repeated batch production. The porous poly(styrene-divinylbenzene) immobilized Phanerochaete chrysosporium and freely suspended mycelial pellets were used as biocatalysts for the degradation of 2-chilorophenol in a 2-L bioreactor. The porous poly(styrene-divinylbenzene) particle (diameter ≅ 0.2 cm) immobilized spores exhibited a much higher activity in the degradation of 2-chlorophenol than the freely suspended mycelial pellets. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 394-397 
    ISSN: 0006-3592
    Schlagwort(e): cellulose ; immobilization ; fiber ; titanium oxide ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Fibers of a cellulose-TiO2 composite were prepared by the reaction of cellulose with titanium iso-propoxide. Enzymes were immobilized on the fibers easily and simply under mild conditions. The fibers were stable in common solvents, high ionic solutions, and over a wide range of pH values 3-10. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 647-653 
    ISSN: 0006-3592
    Schlagwort(e): yeast ; continuous-flow 31P NMR ; intracellular pH ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Phosphorus-31 nuclear magnetic resonance (31P NMR) was used to compare the anaerobic metabolism of glucose by suspended and gel-entrapped Saccharomyces bayanus cells. The fermentation of glucose was carried out in a reaction system with continuous circulation through the NMR sample tube. The intracellular pH and the levels of some phosphorylated compounds were the levels of some phosphorylated compounds were noninvasively monitored by 31P NMR while glucose, fermentation products, and biomass were determined by analytic techniques comparisons showed that no significant differences are observed in the relative concentrations in the spectra, but distinct profiles for the variation of both intracellular and extracellular pH are found. The internal pH of immobilized cells is maintained at a constant value throughout the fermentation as opposed to freely suspended cells for which a steady decrease in the internal pH occurs. A faster and stronger acidification is also observed in the external medium of the assays with suspended cells. Furthermore, higher yields for ethanol and biomass production and lower yields of fermentation by-products are obtained with immobilized cells. It is concluded that the higher intracellular pH achieved in the presence of the gel matrix had a regulatory effect on the metabolism which favored the ethanol production pathway. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 833-836 
    ISSN: 0006-3592
    Schlagwort(e): phospholipase D ; adsorptive immobilization ; calcium ; stabilization ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Immobilization of phospholipase D from cabbage was studied with the aim of stabilizing the enzyme for its use in synthesis of phospholipids. It was shown that phospholipase D can be immobilized by adsorption to polymeric carriers containing long chain anchor groups such as octadecyl, octyl, or other alkyl residues. Starting from the crude enzyme, phospholipase D activity is preferentially bound (up to 100%) in competition with contaminating proteins. A prerequisite of high binding rates is the presence of calcium ions, which play a mediating role in the adsorption process. The maximum activity of the carrier-enzyme complexes depends upon the calcium concentration in the immobilization process and the carrier material (≥10mM CaCl2 with octadecyl-Si40, ≥40 mM CaCl2 with octyl-sepharose and butyl-fractogel). Immobilization of phospholipase D to octyl-sepharose was shown to result in a distinctly increased storage stability and an enlarged pH-optimum range for the catalytic activity. Operational stability of different phospholipase D-carrier complexes was compared. © 1993 Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 8
    ISSN: 0006-3592
    Schlagwort(e): thyroid cells ; immobilization ; photografting ; photocatalyst ; thryrotrophin bioassay ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Viable and functionally responsive human thyroid follicular cells, suspended in a commercial polyester acrylate diluted with tripropyleneglycol diacrylate, photoinitiated, and photocatalyzed with a proprietary photocatalytic system based on a synergic mixture of vanadium (V) t-butoxide and i-propoxide, have been immobilized as monolayers onto polystyrene plates. Bioassay of thyrotrophin in immobilized cell cultures yielded, by log-log plot of the dose-response curve, a slope (0.92 ± 0.02) in close agreement with that (0.91) reported for cells immobilized by physical adsorption. The decisive role of photocatalyst in the photografting procedure has also been shown experimentally. A mechanism is suggested by which cells are anchored, rapidly and with stable chemical bonds, onto one of the two acrylate functions of the monomer-prepolymer mixture, the other one being simultaneously responsible for photochemical grafting onto the support. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 267-278 
    ISSN: 0006-3592
    Schlagwort(e): biocatalyst ; immobilization ; analytical effectiveness factor ; substrate inhibition ; phenol degradation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A reaction engineering model for the degradation of an inhibitory substrate by a steady-state biofilm is presented. The model describes both the metabolic rate controlling behavior of this substrate in the biofilm and the effect of diffusion limitation caused by an arbitrary substrate on the active biofilm thickness. An analytical expression for the biocatalyst effectiveness factor is presented on the basis of Pirt kinetics for cell maintenance, first order substrate inhibition kinetics, and zero order substrate consumption kinetics. The proposed expression for the biocatalyst effectiveness factor is much more convenient to incorporate into a macroreactor model than the numerical alternatives. Simple criteria are presented to check the applicability of the model in case of true Monod kinetics. The analytical solution is expected to be particularly applicable to processes where a low soluble organic substrate controls the biomass growth, a situation which is often met in wastewater purification processes of industrial importance. The degradation of phenol by Pseudomonas sp. is treated as an example. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1131-1135 
    ISSN: 0006-3592
    Schlagwort(e): hybridoma ; instability ; immobilization ; monoclonal antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Loss of monoclonal antibody (MAb) productivity in long-term, free-suspended cell culture is often attributed to the appearance of a nonproducing population of hybridoma cell (NP) in the culture which has a growth advantage over the producing population (P). However, when an NP appears in long-term culture of entrapped cells, it may not be able to take over the whole culture in a short period of time due to the limited growth of the entrapped cells. In order to examine the hypothesis that entrapped cells can have improved stability of MAb productivity due to limited cell growth, free-suspended cell culture and calcium alginate-entrapped cell culture with inocula consisting of a P and an NP were compared with regard to stability of MAb productivity in a repeated fed-batch culture. In free-suspended cell culture, the NP appeared to take over the whole culture within three batches, and thereby MAb production completely disappeared. In entrapped cell culture, an NP appeared to outgrow the P rapidly only during an exponential growth phase, resulting in a significant decrease in specific MAb productivity, qMAb, from 11.58 μg/106 cell/day to 2.76 μg/106 cell/day. However, when the cell growth was limited in entrapped cell culture, the NP no longer outgrew the P rapidly, as indicated by the stable value of qMAb. In addition, when the cells recovered from the alginate beads by citrate buffer treatment were subcultured in free-suspended cell culture, MAb production rapidly deteriorated and completely disappeared within two batches. Thus, the P present at a small fraction of viable cell concentration in the beginning of the free-suspended cell culture, which were previously entrapped in alginate beads, seemed to be outgrown rapidly by the NP. Taken together, the results obtained from these experiments support the hypothesis that the limited cell growth in entrapped cell culture, which keeps an NP from taking over the whole culture, is responsible, in part, for the improved stability of MAb productivity. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 204-210 
    ISSN: 0006-3592
    Schlagwort(e): immobilization ; interesterification ; cocoa butter equivalent ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In order to investigate quantitatively the interesterification reaction, triolein and stearic acid were used as substrates and eight commercially available lipases were tested for their suitability for the reaction. Three fungal lipase preparations were found to be suitable. The hydrolytic activity of the commercial lipases was tested with olive oil, and it 2was noted that there was no correlation between their hydrolytic and interesterification activities. Among the lipases tested, Mucor miehei lipase was chosen for further study because of it high protein content and its relatively high hydrolytic and interesterification activities, both of which are required for effective interesterification. The effect of water activity of the interesterification reaction was investigated. interesterification activity was shown to be maximum at the water activity of 0.25. As the water activity of the lipase increased, hydrolysis of triglyceride was accelerated. At zero water activity, high conversion was achieved, although interesterification activity was relatively lower than that at the water activity of 0.25. A new and simple immobilization method was developed in order to render hydrophobicity to the lipase and hence to improve the interesterification activity of the lipase. The lipase was immobilized covalently with glutaraldehyde or with six alkyl chains as spacers onto Florisil (magnesium silicate, a inorganic matrix). Interesterification activity of the immobilized lipase with the hydrophobic spacers were increased against that of re lipase. The increase of activity was up to 8-fold that of the original activity of free lipase when the spacer was 7-aminoheptanoic acids. Relatively high stability of the immobilized lipase was shown in a continuous packed bed column reactor with a half-life of 97 days. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 171-178 
    ISSN: 0006-3592
    Schlagwort(e): enzyme stabilization ; additive ; immobilization ; support material ; organic media ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Enzymes deposited on solid support usually show good stability when operated in organic solvents. Decreased stability of the enzyme preparations was noticed when low enzyme loadings were used (e.g., with Celite as support; less than 1 mg enzyme/g). It was possible to avoid the activity loss by the addition of an additive which protects the enzyme during the immobilization. Proteins (such as albumin, gelatin, and casein) and poly(ethylene glycol) were effective additives whereas amino acids, monomeric carbohydrates, and polysaccharides had no effect. The amount of additive needed for stabilization was shown to depend on the structure of the support, more additive being required for a support with high porosity. The stabilizing effect was investigated in a series of glyceryl-controlled-pore glass (CPG) with varying specific surface areas (9.5-180 m2/g). The minimum addition of albumin, giving full stabilization, on the different supports correlated to a monolayer coverage of the surface, approximately 2-3 mg protein/m2. The effect of the additive was less pronounced when increasing amounts of enzyme were immobilized (5-40 mg enzyme/g Celite). The effect of the additives was studied using mandelonitrile lyase, but α-chymotrypsin and lipase P were also shown to be stabilized. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 854-858 
    ISSN: 0006-3592
    Schlagwort(e): phenol ; tyrosinase ; immobilization ; chitosan ; immobilized enzyme ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An enzymatic method for removal of phenols from industrial wastewater was investigated. Phenols in an aqueous solution were removed after treatment with mushroom tyrosinase. The reduction order of substituted phenols is catechol 〉 p-cresol 〉 p-chlorophenol 〉 phenol 〉 p-methoxyphenol. In the treatment of tyrosinase alone, no precipitate was formed but a color change from colorless to dark-brown was observed. The colored products were removed by chitin and chitosan which are available abundantly as shellfish waste. In addition, the reduction rate of phenols was observed to be accelerated in the presence of chitosan. Tyrosinase, immobilized by using amino groups in the enzyme on cation exchange resins, can be used repeatedly. By treatment with immobilized tyrosinase, 100% of phenol was removed after 2 h, and the activity was reduced very little even after 10 repeat treatments. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 697-706 
    ISSN: 0006-3592
    Schlagwort(e): anchorage-dependent mammalian cells ; immobilization ; fibers ; bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Anchorage-dependent HeLa cells were successfully cultured on two fibrous materials (A07 and R100) with porosities of 75-125 and 40 μm, void fractions of 92% and 81%, and fiber diameters of 7.6 and 10.2 μm, respectively, in 100-mL spinner flasks and 2-L stirred tank bioreactors. The matrix was formed into a fixed vertical spiral configuration. All cultures displayed rapid (≤2-3 h) attachment of inoculated cells (≥95%) to the matrix, uniform coverage of the immobilizing area with viable cells, and no significant amount of cell debris in the medium. Spinner flask cultures indicated that the denser material R100 showed better results in terms of final cell density. The growth of HeLa cells on material R100 in both culture systems was similar to that observed in tissue culture dishes (specific growth rate ∼0.03-0.04 h-1, maximum cell density of 8 × 106-9 × 106 cells · mL-1, and yields of 0.4 × 108 cells · mM-1 on glucose and 2 × 108-3 × 108 cells · mM-1 on glutamine). Scale-up of this culture technique in a 2-L bioreactor under perfusion with pH and dissolved oxygen (DO) control yielded cell densities of up to 1.6 × 106 cells · mL-1. Two other anchorage-dependent mammalian cells (ADC) known to be cultured with difficulty in roller bottles or with micro carriers were easily grown on material R100 in spinner flasks. The performance of this culture technique was compared to other ADC culture systems.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 1080-1085 
    ISSN: 0006-3592
    Schlagwort(e): immobilization ; mitochondrial membranes ; cytochrome oxidase ; ATPase, concanavalin A-Sepharose ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A fraction (15-20% of the total protein) of a preparation of bovine submitochondrial particles (SMPs) binds to concanavalin A-sepharose. The bound membranes displayed succinate dehydrogenase, cytochrome oxidase, and ATPase activity, which, as in SMPs, were inhibited by malonate, cyanide, and oligomycin, respectively. These results indicate that the bound membranes are inner mitochondrial membranes and that they contain a glycoprotein which was recognized by concanavalin A. It was possible to repeatedly perform the three enzyme assays, one after the other, in the same gel with the bound membranes. Long-term stability tests (22 days) showed that cytochrome oxidase was much more stable in the membranes bound to the gel than in SMPs, while the ATPase activity decayed at a similar rate in the two conditions. Thus, inner mitochondrial membranes bound to ConA-Sepharose appear to be a potentially interesting model for the study of immobilized multienzymatic complexes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1319-1327 
    ISSN: 0006-3592
    Schlagwort(e): immobilization ; chemical adsorption ; alumina ; phosphate ; papain ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The chemical adsorption of organic phosphate compounds to alumina has been used to create surface linkers for protein immobilization. A number of particulate alumina supports were screened for their physical properties and ability to bind organic phosphate compounds. Two aluminas, termed C1 and CPC, were selected based on their suitability for subsequent testing as protein immobilization supports. Papain was successfully immobilized to these supports when derivatized with phosphate compounds containing free terminal carboxyl groups. Protein binding was enhanced when support carboxyl groups were activated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The level of papain immobilization was dependent upon the length of the linker used and the mass of protein exposed to the support. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1328-1336 
    ISSN: 0006-3592
    Schlagwort(e): immobilization ; papain ; alumina ; kinetics ; fluorescence ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Particulate aluminum oxides (alumina) were examined as supports for the immobilization of the proteolytic enzyme papain. Two alumina supports termed C1 and CPC were derivatized using organic phosphate linkers to create free carboxyl groups using a two-step process. Papain binding to these derivatized aluminas was performed using the water soluble carbodiimide 1-ethyl-3-(dimethylaminopropyl) carbodiimide. Reactions were optimal at 10 mM carbodiimide. The immobilized protein showed similar kinetic constants when compared to the solution protein. The pH dependence and thermal stability were essentially identical. The immobilized papain showed a blue shift in the intrinsic fluorescence emission maxima. Papain modified with the active site-specific fluorescent probe acrylodan showed overlapping emission maxima. These results are interpreted as retention of the hydrophobic environment of the active site with a perturbation in the structure of the rest of the protein caused by its association with the negatively charged surface. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1123-1127 
    ISSN: 0006-3592
    Schlagwort(e): steriod Δ1-dehydrogenation ; immobilization ; Arthrobacter simplex ; polyurethane ; organic media ; thermostability ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Whole Arthrobacter simplex cells entrapped in κ-carra-geenan or in two types of polyurethane foam, or adsorbed on silanized Celite, were tested for the Δ1-dehydrogenation of hydrocortisone and its derivatives in organic media. Catalytic activity and stability levels were evaluated for the immobilized cells in buffer with 2.5% (vol/vol) methanol, and in three buffer-saturated solvents (n-octan-1-ol, n-decan-1-ol, and chloroform). The addition of glutamate to the immobilization support stabilized the activity of the immobilized cells in the tested organic media. The system with polyurethane (HYPOL6100)-entrapped cells (with coimmobilized glutamate) in n-decan-1-ol provided the highest long-term activity levels. Several factors involved in the polyurethane-entrapment procedure were also studied. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 638-642 
    ISSN: 0006-3592
    Schlagwort(e): catalase ; Saccharomyces cerevisiae ; polyacrylamide gel ; immobilization ; permeabilization ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The permeabilization of Saccharomyces cerevisiae (baker's yeast), either before or after immobilization in polyacrylamide gel (PAG), has been examined as a means to increase the catalase activity of PAG-immobilized yeast cells. Prior permeabilization of the cells resulted in large losses of catalase activity during immobilization, but permeabilization after immobilization produced increases in the catalase activity of yeast/PAG particles. A dependence of the accessible catalase activity on the concentration of polyacrylamide in permeabilized yeast/PAG particles, and on the method of permeabilization of the immobilized cells, was observed. Optimal levels of stable catalase activity (1000-2000 IU/g PAG particles; ca. 5%-10% of total available activity) were obtained by immobilizing yeast cells (0.5 g wet cells/mL gel) in 10% (w/v) PAG, followed by permeabilization of the entrapped cells with either cetyltrimethylammonium bromide, Triton X-100 and one freeze-thaw, or five freeze-thaw cycles. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 997-1003 
    ISSN: 0006-3592
    Schlagwort(e): invertase ; sucrose hydrolysis ; polystyrene resin ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Invertase from baker's yeast (Saccharomyces cerevisiae) covalently bound to a macroporous polystyrene anion-exchange resin via glutaraldehyde was applied to continuous sucrose hydrolysis in packed bed-reactors. The process was scaled up from 3-mL laboratory reactors via 0.3-L reactors to pilot-scale 50-L reactors without significant loss of efficiency. The described process allows the production of a wide spectrum of invert sugar syrups with high purity in continuous procedure. The 50-L reactor was used under process conditions 1 year without significant loss of productivity at a temperature of 40°C. A productivity of 760 g/h was obtained with 1 L invertase-polystyrene complex using a 2.5M sucrose solution as substrate. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 21
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 748-752 
    ISSN: 0006-3592
    Schlagwort(e): lipase ; immobilization ; DEAE-sephadex ; organic solvent ; continuous hydrolysis reaction ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Lipase (EC 3.1.1.3) from Candida rugosa was immobilized with DEAE-Sephadex A50, Sephadex G50, Sephadex LH-20, Amberlite IRA94, and Amberlite XAD-7. The enzye immobilized with DEAE-Sephadex A50 was found to be most effective for continuous hydrolysis of olive oil in isooctane. For the continuous reaction, 0.2 g of dry immobilized enzyme was swollen with predetermined amount of water, and packed in a glass column reactor. When the organic solvent (Isooctane) containing olive oil substrate was cocurrently fed with aqueous buffer, the two phases were evenly distributed throughout the packed bed without surfactant supplement or prior mixing of the two phases. A small amount of the surfactant (AOT) was used only in packing procedure, and no additional surfactant was necessary thereafter. Effects of initial water content of the swollen gel, buffer types, and strength were examined in the continuous reaction. Our results suggest that the operational half-life was affected by desorption of the bound enzyme. Under the conditions of 20% olive oil in isooctane and 25 mM triethanolamine buffer (pH 7.0), operational half life was 220 h at 30°C. The reactor was also operable with n-hexane, but the operational stability of the immobilized enzyme in n-hexane was only half of that in isooctane. Our results indicate that various enzyme carrier having hydrophilic or amphiphilic properties could be used for two-phase continuous reaction in packed-bed column, reactor without any surfactant supply or prior dispersion of the two immiscible phases. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1203-1209 
    ISSN: 0006-3592
    Schlagwort(e): urease ; immobilization ; polyurethane foam ; biofilm reactor model ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The immobilization of urease on the reticulated polyurethane foam, and the kinetic phenomenon of urea hydrolysis by the resulting immobilized urease in both batch squeezer and circulated flow reactors were studied. Urease was immobilized with bovine serum albumin and glutaraldehyde on polyurethane foam support of 7 to 15 μm thickness. The residual apparent activity of urease after immobilization was about 50%. The good hydrodynamic property and flexibility of polyurethane foam were retained in solution after immobilization. A modified biofilm reactor model was used to describe the kinetic phenomenon of urea hydrolysis in both batch squeezer and circulated flow reactors. The characteristic parameters of the reactor model for both bioreactors were obtained by combining the Rosenbrock optimization method, the Rungs-Kutta method, and the Newton-Raphson method. The best-fit results were in good agreement with the experimental data. This study suggests another application of polyurethane foam in enzyme immobilization and immobilized enzyme reactors, which offers potential for practical applications in various bioreactors. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 1029-1036 
    ISSN: 0006-3592
    Schlagwort(e): immobilization ; protein production ; continuous culture Saccharomyces cerevisiae ; plasmid stability ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The Saccharomyces cerevisiae strain Mc16/p520 has an unstable plasmid, p520, which directs production of a wheat α-amylase. The effects of immobilizing this microorganism on the plasmid stability and the specific productivity of the secreted α-amylase were investigated. Small gelatin beads were used as the support in both fluidized and packed bed configurations, and the yeast cells were attached by covalent cross-linking with glutaraldehyde. These data were then compared to those for nonimmobilized, suspension cells.Plasmid stability was increased for the immobilized cells during continuous culture at dilution rates both above and below washout. Continuous suspension cultures were not stable and rapidly lost the plasmid. Immobilization caused an increase in specific and volumetric productivity during continuous culture, with a packed bed design resulting in the highest specific productivity.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 1050-1053 
    ISSN: 0006-3592
    Schlagwort(e): hybridomas ; immobilization ; oxygen ; respiration ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Oxygen consumption by hybridoma cells immobilized in 1- and 3.9-mm-diameter calcium alginate beads was measured. The entrapped cells consumed oxygen at about 10 μmol/min per 109 cells, regardless of the bead size and cell loading. In contrast, the same cells in suspension culture respire at specific rates of 3-8 μmol/min per 109 cells (depending on the cell density). The growth rate of the immobilized cells was significantly reduced, while specific antibody production was comparable to that of free cells.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1041-1049 
    ISSN: 0006-3592
    Schlagwort(e): diffusion ; lactose ; get matrix ; immobilization ; growing cells ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Effective diffusion coefficients (De) of lactose in κ-carrageenan (2.75% wt/wt)/locust bean gum (0.25% wt/wt) (LBG) gel beads (1.5-2.0-mm diameter)with or without entrapped lactic acid bacteria (LAB) were determined at 40°C. The effects of lactose concentration, bacteria strain (Streptococcus salivarius subsp. thermophilus and Lactobacillus casei subsp. casei) and cell content at various steps of the fermentation process (after immobilization, pre-incubation of the beads and successive fermentations) were measured on De as a first step for process modelling. Results were obtained from transiend concentration changes n well-stirred lactose solutions in which the beads were suspended. A mathematical model of unsteady-state diffusion in a sphere was used, and De was obtained from the best fit of the experimental data. Diffusivity of lactose in cell-tree beads was significantly lower than in pure water mainly because of the obstruction effect of the polymer chains and the hydration region. Furthermore, effective diffusivity and equilibrium partition factor were independent of lactose concentration in the range from 12.5 to 50 g/L. No significant difference was found for De (effective diffusivity) and Kp (partition) coefficients between beads entrapping S. thermophilus (approximately 5 × 109 CFU/mL) and cell-free beads. On the other hand higher cell counts obtained with L. casei (close to 1.8 × 1011 CFU/mL) increased mass transfer resistance resulting in lower effective diffusivities and Kp. Finally, the effects of the type of bacteria and their distribution in the beads on the diffusivity were also discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1285-1291 
    ISSN: 0006-3592
    Schlagwort(e): Tripterygium Wilfordii ; plant cell culture ; suspension ; medium ; immobilization ; bioreactor culture ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The plant Tripterygium wilfordii produces di- and triterpenes of interest for male contraception and treatment of arthritis and skin disorders. Cell line TRP4a obtained form this plant in 1981 was reported to produce these valuable compounds at yields (∼0.04% of the biomass dry weight) higher than found in the plant (0.001%). In order to improve this production, studies were carried out to determine the feasibility of eliminating the troublesome component of coconut milk originally used to culture this cell line. A defined formulation suitable for growth ad maintenance has been developed. This medium consisted of Gamborg's PRL4 or B5 medium supplemented with 2 mg L-1 2,4-dichlorophenoxyacetic acid and 20 g L-1 sucrose. Furthermore, monitoring of carbohydrate uptake revealed that T. wilfordii cells, contrary to many plant cell species, did not hydrolyze sucrose extra-cellularly before uptake. Replacement of this disaccharide by glucose or fructose increased specific growth rate from 0.15 to 0.25 day-1. As tripdiolide is reported to be present in broth extract in significant amounts, plant cell immobilization technology offers a promising alternative to suspension cultures, especially in view to on line harvesting of the product. Surface immobilized T. wilfordii cell cultures were successfully carried out in 2-L bioreactors. Their biomass production and carbohydrate uptake were comparable to those observed for shake flask grown suspension cultures. Higher nitrate and ammonium uptake were found in immobilized cultures.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 727-732 
    ISSN: 0006-3592
    Schlagwort(e): lipase kinetics ; Candida cylindracea ; hydrolysis of triacetin ; hollow-fiber membrane reactor ; immobilization ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The aptitude of a hollow-fiber membrane reactor to determine lipase kinetics was investigated using the hydrolysis of triacetin catalyzed by lipase from Canadida cylindracea as a model system. The binding of the lipase to the membrane appears not to be very specific (surface adsorption), and probably its conformation is hardly altered by immobilization, resulting in an activity comparable to that of the enzyme in its native form. The reaction kinetics defined on the membrane surface area were found to obey Michaelis-Menten kinetics. The specific activity of the lipase in the membrane reactor was found to be significantly higher than in an emulsion reactor. The activity and stability of the enzyme immobilized on a hydrophilic membrane surface seem not to be influenced significantly by the choice of the membrane material. The hollow-fiber membrane reactor is a suitable tool to assess lipase kinetics in a fast and convenient way.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 28
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 544-550 
    ISSN: 0006-3592
    Schlagwort(e): immobilization ; extractive fermentation ; Lactobacillus delbrueckii ; k-carrageenan ; mass transfer ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The use of immobilization in extractive lactic acid fermentation by Lactobacillus delbrueckii is preferred. In this article, the mathematical simulations to examine the influences of substrate and product transport were performed to assess the overall performance. The simulations showed that transport of the substrate in k-carrageenan beads was not a rate limiting factor. However, the model observed significant buildup of inhibitory product in large beads. The model was validated through comparisons with the experimental results. Finally, the model was used to predict the performance of the extractive fermentation under different operating strategies.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 29
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 551-556 
    ISSN: 0006-3592
    Schlagwort(e): Methylosinus trichosporium ; methanol biosynthesis ; immobilization ; batch and continuous studies ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The DEAE-cellulose linked cells of Methylosinus trichosporium displaying high specific methane mono-oxygenase activity (66 μmol methane oxidized/h mg cells) were used for methanol biosynthesis from biogas derived methane in a batch and a continuous cell reactor. The optimum cell-to-carrier ratio was determined to be 0.5 g cells/g dry weight cellulose. Batch experiments indicated that 100 mM phosphate ion concentration was necessary to inhibit further oxidation of methanol; excess oxygen supply favored methanol accumulation with an increase in methane conversion efficiency to 27%. A pulse of 40 mM sodium formate at the end of 6 h resulted in restoration of methanol accumulation by regenerating NADH2 required for the sustained activity of methane mono-oxygenase. Maximum methanol level of 50 μmol/mg cells was obtained in the batch reactor. In a standard 50-mL ultrafiltration continuous reactor, the covalently linked cells produced methanol at a continuous rate of 100 μmol/h for the first 10 h, after which the methanol accumulation rate fell low due to the depletion of NADH2. The methanol accumulation could be stimulated by supplying sodium formate (40 mM) in either 20 or 100 mM phosphate buffer. Maximum methanol accumulation rate of 267 μmol/h was obtained when 20 mM formate was supplied in the feed stream containing 100 mM phosphate ions, and this level of biosynthesis was maintained for over 72 h. The stoichiometric balance made at various points of formate addition indicated that the molar amount of methanol generated at steady state is dependent on the equimolar addition of sodium formate to the feed. The half-life t1/2 and thermal denaturation rate constant Kd were computed to be 108 h and 6.42 × 10-3 h-1, respectively.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 854-858 
    ISSN: 0006-3592
    Schlagwort(e): Polypyrrole ; glucose oxidase ; immobilization ; autoinactivation ; thermodesactivation ; stability ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: This article reports the characterization of the biochemical behavior of glucose oxidase entrapped in polypyrrole. The immobilization of glucose oxidase in a polypyrrole film was performed by entrapment during the electropolymerization of pyrrole at a platinum electrode poised at 0.65 V vs. SCE in aqueous solution in a one-compartment electrochemical cell. Thin films of polypyrrole (0.11 μm) were obtained and the entrapped enzyme obeyed Michaelis kinetics, indicating no diffusional constraints of the substrate. Our results indicate that the entrapped glucose oxidase is more resistant to denaturation conditions such as alkaline pH and temperature (50 and 60°C) than the soluble form of the enzyme. The autoinactivation constant for the entrapped enzyme was also determined in presence of 0.25M of glucose and was 6.19 × 10-4 min-1, i.e., corresponding to a half-life value of 20 h. The results reported here show clearly that polypyrrole matrix has a strong stabilizing effect on the stucture and on the activity of glucose oxidase.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 821-830 
    ISSN: 0006-3592
    Schlagwort(e): hybridoma ; immobilization ; serum ; flow cytometry ; antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effect of serum on cell growth and monoclonal antibody (MAb) productivity was studied in a repeated fedbatch mode using both free-suspended and immobilized S3H5/γ2bA2 hybridoma cells. In the suspension culture, serum influenced the cell growth rate but not the specific MAb productivity. The average specific growth rate of the suspension culture in medium containing 10% serum was approximately 0.99 ± 0.12 day-1 (±standard deviation), while that in medium containing 1% serum was approximately 0.73 ± 0.12 day-1. The specific MAb productivity was almost constant at 3.69 ± 0.57 μg/106 cells/day irrespective of serum concentration reached a maximum at ca. 1.8 × 106 cells/mL of medium in 10% serum medium, and the cell concentration was gradually reduced to 1%. The specific MAb productivity of the immobilized cells was more than three times higher than that of the free-suspended cells. The amount of serum in the medium did not influence the specific MAb production rate of the immobilized cells. The maintenance of high cell concentration and the enhanced specific MAb productivity of the immobilized cell culture resulted in a higher volumetric MAb productivity. In addition, MAb yield in the immobilized cell culture with medium containing 1% serum was 2.2 mg/mL of serum, which was approximately three times higher than that in the suspension culture.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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