bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular imprinting of proteins and other macromolecules resulting in new adsorbents
Authors: Dabulis Katherine , Klibanov Alexander M. 
Published: December 2004

AbstractWhen the model protein bovine serum albumin (BSA) was dissolved in a concentrated aqueous solution of the multifunctional ligand L‐malic acid, the solution was lyophilized, and the solid residue thoroughly washed with tetrahydrofuran to extract malic acid, then the resultant (“imprinted”) protein was capable of binding 26.4 ±0.9 mol equivalents of the ligand in anhydrous ethyl acetate. The nonimprinted BSA (i.e., that prepared in the same manner apart from the absence of malic acid) bound less then one‐tenth of that amount under identical conditions. Furthermore, both imprinted and nonimprinted BSA exhibited little binding of L‐malic acid in water. The imprinted BSA retained its “memory” for the ligand in ethyl acetate even after a prolonged incubation under vacuum; dissolution in water, however, eliminated the imprinted protein's binding capacity. The BSA imprinted with L‐malic acid displayed affinity for this ligand not only in ethyl acetate but also in many other anhydrous solvents. It was found that the higher the solvent's propensity to form hydrogen bonds, the lower the protein–ligand binding in it, thus pointing to hydrogen bonds as the driving force of this binding. Studies with completely or partially cleaved BSA, with other globular proteins, glutathione, and poly(L‐aspartic acid) revealed that the critical requirement for the imprintability is the presence of a sufficiently long polymeric chain. Moreover, many hydrogen‐bond‐forming macromolecules other than proteins, such as dextrans and their derivatives, partially hydrolyzed starch, and poly(methacrylic acid), also could be imprinted for subsequent binding in ethyl acetate. The mechanism of imprinting and binding inferred from these experiments involves a multipoint hydrogen bonding in water of each ligand molecule with two or more sites on the polymeric chain, thereby folding a segment of the latter into a cavity around the ligand; following lyophilization and extraction of the ligand, the cavities remain in organic solvents (but not in water) and give rise to ligand binding. This conclusion is supported by the results of binding of numerous malic acid analogs and related ligands to BSA imprinted with L‐malic acid. Finally, BSA imprinted with malic acid was used as a selective adsorbent for a chromatographic separation of an equimolar mixture of maleic and acrylic acids in ethyl acetate.
Use of a structured kinetic model of antibody synthesis and secretion for optimization of antibody production systems: II. Transient analysis
Authors: Bibila Theodora A. , Flickinger Michael C. 
Published: December 2004

AbstractThe dynamic behavior of the monoclonal antibody (MAb) secretory pathway is studied by transient simulations using our previously developed structured kinetic model for antibody synthesis and secretion by hybridoma cells. The response of the secretory pathway to blocks in specific pathway steps and step changes in characteristic pathway parameters is presented in order to gain a better understanding of pathway dynamics and identify possible ratelimiting steps in the pathway. Model simulations suggest that the step of antibody assembly in the endoplasmic reticulum (ER) is a very good candidate for a rate‐limiting step in the antibody secretory pathway in fast‐growing hybridoma cells, whereas translation of the heavy and light chains is most likely rate–limiting in slowly growing or stationary phase cells. Transient simulation results are compared with experimentally observed transient changes in specific antibody secretion rates and used to suggest strategies for optimizing antibody secretion in large‐scale production systems.
Production of soluble sugar from cellulosic materials by repeated use of a reversibly soluble‐autoprecipitating cellulase
Authors: Taniguchi Masayuki , Hoshino Kazuhiro , Watanabe Kouichi , Sugai Kazuhito , Fujii Michihiro 
Published: December 2004

AbstractA reversibly soluble‐autoprecipitating cellulase was prepared by covalently immobilizing Meicelase on an enteric coating polymer (AS‐L, hydroxypropyl methylcellulose acetate succinate). The immobilized enzyme (M‐AS) was reversibly soluble‐insoluble depending on the pH of the reaction medium. Moreover, the enzymatic activity of M‐AS, in a soluble state, for microcrystalline cellulose was higher than that of the conventional solid immobilized enzyme. On the other hand, M‐AS, in an insoluble state, and good properties of self‐sedimentation, and a large portion of M‐AS spontaneously precipitated for about 15 min at pH 3.8. In the repeated hydrolysis of rice straw, delignified with sodium hydroxide using a bioreactor with a conical bottom, M‐AS was separated batchwise from a production solution by self‐sedimentation in a conical bottom of the bioreactor. When delignified, rice straw was hydrolyzed repeatedly by reuse of M‐AS; the total amount of soluble sugar produced from 5 g of delignified rice straw was 2.7 g. Further, by the hydrolysis method with repeated removal of reaction inhibitors (soluble sugar), the time required for converting the same amount of delignified rice straw to soluble sugar was significantly reduced, as compared with that by the standard reaction method.
Glucose‐limited chemostat culture of chinese hamster ovary cells producing recombinant human interferon‐γ
Authors: Hayter Paul M. , Curling Elisabeth M. A. , Baines Anthony J. , Jenkins Nigel , Salmon Ian , Strange Phillip G. , Tong Jeremy M. , Bull Alan T. 
Published: December 2004

AbstractA Chinese hamster ovary (CHO) cell line expressing recombinant human interferon‐γ (IFN‐γ) was grown under glucose limitation in a chemostate at a constant dilution rate of 0.015 h−1 with glucose feed concentrations of 2.75 mM and 4.25 mM. The changes in cell concentration that accompanied changes in the glucose feed concentration indicated that the cells were glucose‐limited. The cell yield on glucose remained constant, but there was a decline in residual glucose concentration and a reduced lactate yield from glucose in the latter stages of the culture. The consumption rates for many of the essential amino acids were increased later in the culture. The volumetric rate of interferon‐γ production was maintained throughout the course of this culture, indicating that IFN‐γ expression was stable under these conditions. However, the specific rate of IFN‐γ production was significantly lower at the higher glucose feed concentration. Under glucose limitation, the proportion of fully glycosylated IFN‐γ produced by these cells was less than that produced in the early stages of batch cultures. The proportion of fully glycosylated IFN‐γ increased during transient periods of glucose excess, suggesting that the culture environment influences the glycosylation of IFN‐γ.
Compact automated displacement gas metering system for measurement of low gas rates from laboratory fermentors
Authors: Angelidaki I. , Ellegaard L. , Ahring B. K. 
Published: December 2004

AbstractAn automated metering system was developed for measuring biogas production from laboratory scale biogas digestors. The gas metering system is based on the principle of liquid displacement with a 100‐mL reversible cycle and registration. The gas meter is made entirely of plastic and rubber materials resistant to the corrosive components of biogas (e.g., H2S) and requires a 12 to 15 VDC power supply.
Estimation of cell volume and biomass of penicillium chrysogenum using image analysis
Authors: Packer H. L. , Keshavarz‐Moore E. , Lilly M. D. , Thomas C. R. 
Published: December 2004

AbstractA methodology for the estimation of biomass for the penicillin fermentation using image analysis is presented. Two regions of hyphae are defined to describe the growth of mycelia during fermentation: (1) the cytoplasmic region, and (2) the degenerated region including large vacuoles. The volume occupied by each of these regions in a fixed volume of sample is estimated from area measurements using image analysis. Areas are converted to volumes by treating the hyphae as solid cylinders with the hyphal diameter as the cylinder diameter. The volumes of the cytoplasmic and degenerated regions are converted into dry weight estimations using hyphal density values available from the literature. The image analysis technique is able to estimate biomass even in the presence of nondissolved solids of a concentration of up to 30 gL−1. It is shown to estimate successfully concentrations of mycelia from 0.03 to 38 gL−1. Although the technique has been developed for the penicillin fermentation, it should be applicable to other (nonpellected) fungal fermentations.
Effects of ammonia and lactate on hybridoma growth, metabolism, and antibody production
Authors: Ozturk Sadettin S. , Riley Mark R. , Palsson Bernhard O. 
Published: December 2004

AbstractThe influence of ammonia and lactate on cell growth, metabolic, and antibody production rates was investigated for murine hybridoma cell line 163.4G5.3 during batch culture. The specific growth rate was reduced by one‐half in the presence of an initial ammonia concentration of 4 mM. Increasing ammonia levels accelerated glucose and glutamine consumption, decreased ammonia yield from glutamine, and increased alanine yield from glutamine. Although the amount of antibody produced decreased with increasing ammonia concentration, the specific antibody productivity remained relatively constant around a value of 0.22 pg/cell‐h. The specific growth rate was reduced by one‐half at an initial lactate concentration of 55 mM. Although specific glucose and glutamine uptake rates were increased at high lacatate concentration, they showed a decrease after making corrections for medium osmolarity. The yield coefficient of lactate from glucose decreased at high lactate concentrations. A similar decrease was observed for the ammonia yield coefficient from glutamine. At elevated lactate concentrations, specific antibody productivities increased, possibly due to the increase in medium osmolarity. The specific oxygen uptake rate was insensitive to ammonia and lactate concentrations. Addition of ammonia and lactate increased the calculated metabolic energy production of the cells. At high ammonia and lactate, the contribution of glycolysis to total energy production increased. Decreasing external pH and increasing ammonia concentrations caused cytoplasmic acidification. Effect of lactate on intracellular pH was insignificant, whereas increasing osmolarity caused cytoplasmic alkalinization.
Selective recycle of viable animal cells by coupling of airlift reactor and cell settler
Authors: Hülscher Manfred , Scheibler Uwe , Onken Ulfert 
Published: December 2004

AbstractA new system for the perfusion culture of animal cells in suspension is described. It consists of an airlift loop reactor and a settling tank for cell retention. Insufficient nutrient and oxygen supply of the cells in the settling tank was prevented by cooling the cell suspension before entering the settler. As a result, the catabolic activity of the cells in the settler was reversibly reduced. Furthermore, the density gradient induced by cooling caused a liquid motion through the settler. Thus, it was not necessary to pump medium containing shear, sensitive cells. With this simple system, it was possible to prduce 2 to 5 g of antibodies in a 5.4‐L reactor in continuous runs of 400 to 600 h. The productivity was increased by a factor of 17 and the cell density was 4 times higher in comparison with the corresponding batch system. The cell retention system was found to have the property of separating viable and nonviable cells. With the increasing perfusion rate, dead cells and debris were preferably washed out. For perfusion rates up to 1.3 d−1, the retention efficiency of the settler was nearly 100% for viable cells; hence, this system may show advantages at the industrial scale.
Protamine immobilization and heparin adsorption on the protamine‐bound cellulose fiber membrane
Authors: Kim Jae‐Seung , Yang Arthur J. , Yang Victor C. 
Published: December 2004

AbstractImmobilization of protamine to the inner lumen of cellulose hollow fibers has been shown useful in preventing both heparin‐ and protamine‐induced complications during an extracorporeal blood circulation procedure. The current study examined the effects of variables on the immobilization of protamine to cyanogen bromide (CNBr)‐activated cellulose hollow fibers. The degree of protamine immobilization was controlled by three independent parameters: the amount of CNBr used during the activation process, the duration of the coupling process, and the protamine concentration in the coupling solution. By the adjustment of these parameters, cellulose fibers containing desired amounts of immobilized protamine (ranging from 1 to 20 mg of immobilized protamine per gram of dry fibers) were readily prepared.Heparin adsorption to the protamine‐bound cellulose fibers was also examined. The adsorption isotherm followed a Langmuir adsorption model. The amount of heparin adsorbed was dependent on both the heparin concentration in the substrate solution and the protamine loading on the fibers. The Langmuir adsorption constant K was estimated to be 0.37 ± 0.06 mL/mg, whereas the saturation capacity Qs of the protamine‐bound fibers increased with increasing the protamine loading.
Effects of lactate concentration on hybridoma culture in lactate‐controlled fed‐batch operation
Authors: Omasa Takeshi , Higashiyama Ken‐Ichi , Shioya Suteaki , Suga Ken‐ichi 
Published: December 2004

AbstractTo investigate the effects of lactate on cell growth and antibody production, a new method of maintaining the lactate concentration constant in a fed‐batch culture is described. When the pH was initially adjusted by sodium hydroxide, the specific growth rate decreased and specific death rate increased with an increase of lactate concentration. To investigate whether the inhibition was due to the lactate concentration itself or to the osmotic pressure, the effect of the osmotic pressure adjusted by sodium chloride was compared with that of sodium lactate. When the osmotic pressure was adjusted to same condition as that of sodium lactate using sodium chloride, the specific growth data showed the same degree of growth inhibition. It was thus evident that the inhibition to cell growth was mainly due to osmotic pressure while lactate production from glucose was found to be inhibited by the lactate itself compared with sodium chloride. The specific antibody production rate had a maximum value within a certain range of lactate concentration. Moreover, specific antibody production rate had a unified relationship with the kinetic parameter μ, in spite of the different causes of inhibition by lithium lactate and sodium lactate. A certain “trade‐off” relationship between growth and antibody production existed at higher growth rates.
Mixing in liquid‐impelled loop reactors
Authors: Van Sonsbeek H. M. , Van Der Tuin S. P. , Tramper J. 
Published: December 2004

AbstractThe liquid‐impelled loop reactor is a new column‐type bioreactor. The design of this device is based on the principle of the air‐lift loop reactor. In the external‐loop configuration used in this work, descending perfluorochemical drops bring about circulation of the continuous aqueous phase. Mixing of this continuous phase is characterized per section of the rector. Axial‐dispersion coefficients for the tube with two‐phase flow are determined and correlated with the energy dissipation in the tube. Comparisons with similar systems such as bubble columns and air‐lift loop reactors are made. Overall mixing parameters are derived and used for calculation of the number of circulatins needed to achieve a certain degree of mixing. The hydrodynamic model from previous work is tested for the reactor configurations of this work. It can be useful to calculate circulation times.
Rapid protein release from Escherichia coli by chemical permeabilization under fermentation conditions
Authors: Naglak Thomas J. , Wang Henry Y. 
Published: December 2004

AbstractOverall protein release greater than 75% in less than 1 h can be attained by exposing exponentially growing Escherichia coli cells to 0.4 M guanidine plus 0.5% Triton X‐100 at 37°C in medium. Cell growth stops immediately upon addition of the chemicals, but the cells are not lysed. Guanidine concentrations lower than 0.2 M, in conjunction with 0.5% Triton X‐100, do not release significant intracellular protein, nor do they inhibit cell growth. Under these conditions, the cells undergo an adaptation that confers resistance to protein release by further treatment with guanidine and Triton X‐100. Cells treated with 0.2 M guanidine plus 0.5% Triton X‐100 display intermediate behavior. Protein release is approximately 35%, and growth is temporarily interrupted by an extended lag phase. Subsequent resumption of cell growth results in resistant cells and no additional protein release. This resistance is shown to be reversible and is most likely due to physiological adaptation rather than genetic mutation.
Production of superoxide dismutase in Streptococcus lactis by a combination of use of hyperbaric oxygen and fermentation with cross‐flow filtration
Authors: Taniguchi Masayuki , Hoshino Kazuhiro , Itoh Takehiro , Kumakura Hiroshi , Fujii Michihiro 
Published: December 2004

AbstractThe production conditions of superoxide dismutase (SOD) in the cells of Streptococcus lactis by using hyperbaric oxygen (O2) are described. The SOD activity of anaerobically grown cells was 5–6 U/mg protein. When the culture broth was pressurized by O2 at 6 atm, the SOD activity was more than twice as high as that under anaerobic culture conditions. However, there is little or no significant increase in SOD activity by exogenous addition of catalase for detoxifying hydrogen peroxide accumulated in the broth and/or controlling the pH of the broth at 6.8 during the pressurization by O2. The increase in SOD activity by hyperbaric O2 was possible not only at the late‐logarithmic growth phase but also at the initial time for the stationary growth phase. For improvement of SOD productivity, we tried a two‐stage culture in which SOD activity in S. lactis cells was enhanced by pressurizing the culture broth using hyperbaric O2 after achievement of a high‐concentration cultivation in the anerobic fermentation system with a microfiltration module.
Effects of temperature and phosphorous concentration on microbial sulfate reduction by Desulfovibrio desulfuricans
Authors: Okabe S. , Characklis W. G. 
Published: December 2004

AbstractThe effects of temperature and phosphorous concentration on the rate and the extent of microbial sulfate reduction with lactate as carbon and energy source were investigated for Desulfovibrio desulfuricans. The continuous culture experiments (chemostat) were conducted at pH 7.0 from 12 to 48°C. The maximum specific growth rate (μmax) was relatively constant in the range 25°C–43°C and dramatically decreased outside this temperature range. The half‐saturation coefficient was minimum at 25°C. Cell yield was highest in the optimum temperature range (35°C–43°C) for growth. Maintenance energy requirements for D. desulfuricans were not significant. Two moles of lactate is consumed for every mole of sulfate reduced, and this stoichiometric ratio is not temperature dependent. Steady state rate and stoichiometric coefficients accurately predicted transient behavior during temperature shifts. The extent of extracellular polymeric substance (EPS) is related to the concentration of phosphorous in the medium. EPS production rate increased with decreased phosphorous loading rate. Failure to discriminate between cell and EPS formation by D. desulfuricans leads to significant overestimates of the cell yield. The limiting C:P ratio for D. desulfuricans was in the range of 400:1 to 800:1.
Liquid‐Phase mass transfer coefficients in bioreactors
Authors: Kawase Yoshinori , Halard Benoit , Moo‐Young Murray 
Published: December 2004

AbstractLiquid‐phase mass transfer coefficient in bioreactors have been examined. A theoretical model based on the surface renewal concept has been devloped. The predicted liquid‐phase mass transfer coefficients are compared with the experimental data for a mycelial fermentation broth (Chaetomium cellulolyticum) and model media (carboxymethyl cellulose) in a bench‐scale bubble column reactor. The liquid‐phase mass transfer coefficient is evaluated by dividing the volumetric mass transfer coefficient obtained experimentally by the specific surface area estimated using the available correlations. The available literature data in bubble column and stirred tank bioreactors is also used to test the validity of the proposed model. A reasonable agreement between the model and the experimental data is found.
Physico‐chemical features of solvent media in the phases of aqueous polymer two‐phase systems
Authors: Zaslavsky Boris Y. , Borvskaya Anna A. , Gulaeva Nelli D. , Miheeva Larisa M. 
Published: December 2004

AbstractSolvent polarity and pH in the coexisting aqueous phases of aqueous dextran–poly(ethylene glycol) and dextran–Ficoll two‐phase systems of varied polymer concentrations were examined using the solvatochromic technique and potentiometric measurements, respectively. The relative solvent polarity of the phases, as measured by the solvatochromic technique, is suggested as a measure of the hydration power of water in the phases of aqueous polymer systems. Partitioning of a series of sulphonephthalein dyes in aqueous dextran–poly(ethylene glycol) and dextran–Ficoll two‐phase systems of fixed polymer composition containing 0.01 mol/L universal buffer, pH 7.15, was studied. The results obtained are discussed together with those reported earlier on the physico‐chemical features of aqueous media in the coexisting phases of the systems. It is suggested that the two phases of aqueous polymer systems should be viewed as two immiscible water‐like solvents. The implications of the suggestion for the theoretical treatment of aqueous polymer two‐phase systems are discussed.
Enhancement and regulation of extracellular protein production by Bacillus brevis 47 through manipulation of cell culture conditions
Authors: Wright Charlene P. , Whitney Gordon K. , Daugulis Andrew J. , White Bradley N. 
Published: December 2004

AbstractBacillus brevis 47 was cultivated in 2 liter fermentors in semidefined media containing polypeptone with or without glucose or fructose. Neither sugar was essential for growth or extracellular (S‐layer) protein production, and 2.5 to 3.0 g/L protein was accumulated in the medium. When present, glucose was used very slowly, however, fructose was used much more quickly. Dramatic changes in metabolic indicators (dissolved oxygen and pH) were seen when fructose became depleted, and protease was produced, decreasing the amount of protein ultimatelv accumulated in the medium. Using the change in dissolved oxygen as a marker for the time of addition, polypeptone, fructose, or both were used to stimulate protein production. With the addition of polypeptone, on stimulation was achieved, but protease production was suppressed. Addition of fructose did result in a small stimulation of protein production (to 5 g/L) if added once. Further additions resulted in more growth, but no increase in protein production. Various combinations of polypeptone and fructose were also used, with the most effective combination (fructose added early, fructose and polypeptone added later) resulting in an accumulation of 15 g/L protein in the medium. This is comparable to that seen when B. brevis 47 is grown in a complex glucose medium and stimulated with polypeptone addition at 21 hours. These results are discussed with respect to the structure and function of S‐layer proteins, as well as the use of this organism for the production of heterologous proteins.