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  • Biochemistry and Biotechnology  (472)
  • 1985-1989  (472)
  • 1950-1954
  • 1986  (472)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 2
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 16-20 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is described using fast protein liquid chromatography (FPLC) for the monitoring of protein formation during fermentation. The procedure consists of centrifugation to recover the cells, sonication of the cells, centrifugation to remove cell debris, and analysis of supernatant on a column of Mono Q (a strong anion exchanger). Analysis of peak areas provides quantitative determination of product concentration. Maintenance and life of the Mono Q column is discussed. We find that FPLC is a convenient method for measuring products in cell homogenates because it gives rapid, highly resolved separations.
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  • 3
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 21-28 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biosorption of uranium and lead by lyophilized cells of Streptomyces longwoodensis was examined as a function of metal concentration, pH, cell concentration, and culture age. Cells harvested from the stationary growth phase exhibited an exceptionally high capacity for uranium (0.44 g U/g dry weight) at pH 5. Calculated values of the distribution coefficient and separation factor indicated a strong preference of the cell mass for uranyl ions over lead ions. The specific uranium uptake was similar for the cell wall and the cytoplasmic fraction. Uranium uptake was associated with an increase in hydrogen ion concentration, and phosphorus analysis of whole cells indicated a simple stoichiometric ratio between uranium uptake and phosphorus content. It is proposed that metal ions are bound to phosphodiester residues present both in the cell wall and cytoplasmic fractions. Based on this model, it was shown that uranium accumulation exhibits a maximum at pH 4.6 that is supported by experimental data from previous investigations.
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  • 4
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 41-50 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous cellulase production by Trichoderma viride QM 9123, immobilized in 6 mm diameter, spherical, stainless steel biomass support particles, has been achieved using a medium containing glucose as the main carbon source. Experiments were carried out in a 10-L spouted bed fermentor. In this type of reactor-recycled broth is used to create a jet at the base of a bed of particles, causing the particles to spout and circulate. During the circulation, particles pass through a region of high shear near the jet inlet. This effectively prevents a buildup of excess biomass and thus enables steady-state conditions to be achieved during continuous operation. Continuous production of cellulase was achieved at significantly higher yield and productivity than in conventional systems. At a dilution rate of 0.15 h-1 (nominal washout rate for freely suspended cells is 0.012 h-1), the yield of cellulase on glucose was 31% higher than that measured during batch operation, while the volumetric productivity (31.5 FPA U/L· h) was 53% greater than in the batch system. The specific cellulase productivity of the immobilized cells was more than 3 times that of freely suspended cells, showing that diffusional limitations can be beneficial. This offers significant opportunity for the further development of biomass support particles and associated bioreactors.
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  • 5
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 64-72 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Urokinase was immobilized by entrapment to fibrocollagenous tubes in order to develop a small-caliber fibrinolytic vascular prosthesis. Several parameters associated with the immobilization process were studied in order to optimize bound urokinase activity and stability. A total of 37% of the absorbing enzyme was attached to the collagen tube and 38% of the attached enzyme retained esterolytic activity, under optimal conditions. In the crosslink step of the entrapment process, the glutaraldehyde concentration was varied from 0.01 to 5.00% (i.e., 0.01, 0.1, 1.0, 3.0, and 5.0%). Urokinase activity was optimized at a 1.0% glutaraldehyde crosslink concentration. Urokinase-bound fibrocollagenous tubes (UK-FCT) prepared at the above glutaraldehyde concentrations were tested for their activity with time. The UK-FCT's with 0.1, 1.0, and 3.0% glutaraldehyde retained constant activity for at least 75 h operation time. The UK-FCT's with 0.1, 1.0, and 3.0% glutaraldehyde retained constant activity for at least 75 h operation time. The UK-FCT's with 5.0 and 0.01% glutaraldehyde remained stable for the first 50 h operation time, but begandeactivating beyond 50 h. UK-FCT'S Crosslinked with 0.01, 0.1, 1.0, and 5.0% glutaraldehyde were recrosslinked with 0.02% glutaraldehyde for 24 h, after they have been operating for 50 h, and the effect of reexposing the crosslink agent on the stability of the UK-FCT's was studied. The results showed that 0.02% glutaraldehyde reexposure had no effect on 0.1, 1.0, and 5.0% glutaraldehyde crosslinked UK-FCT's but exerted an inhibitory effect on a 0.01% crosslink density UK-FCT. Several fibrocollagenous tubes were exposed to various glutaraldehyde concentrations prior to immobilizing urokinase. The subsequent immobilization process occurred under optimal conditions. The effect of the precrosslink step on the activity of the UK-FCT was studied. Results indicated that UK-FCT activity decreases as the precrosslink density increases. The UK-FCT's made under optimal conditions remained stable for at least 75 h operation time, corresponding to ca.1 year of storage time. Ex vivo exposure of UK-FCT's to whole canine blood did not affect catalytic activity. Implantation of a UK-FCT by carotid arterial interposition via an end-to-end anastomosis and subsequent excision after 60 days resulted in an enhanced esterolytic activity which decreased with time to a level close to preoperative levels.
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  • 6
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    Biotechnology and Bioengineering 28 (1986), S. 101-106 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 7
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    Biotechnology and Bioengineering 28 (1986), S. 110-111 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 8
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    Biotechnology and Bioengineering 28 (1986), S. 115-118 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 9
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    Biotechnology and Bioengineering 28 (1986), S. 119-121 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Absract.
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  • 10
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    Biotechnology and Bioengineering 28 (1986), S. 129-132 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 11
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    Biotechnology and Bioengineering 28 (1986), S. 29-40 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A separate role for water activity in the conversion of sugars to ethanol by two strains of yeast is identified. During fermentation of both single and mixed sugar substrates, the water activity was shown to remain constant during the logarithmic growth phase. This is despite the changes in concentration of substrates and product, the constancy reflecting the fact that the greater influence of ethanol on the solution activity is counterbalanced, in the early stages of the fermentation, by its low yield. The end of the log phase of growth coincides with the start of a period of gradually decreasing water activity. For the more ethanol-tolerant strain UQM66Y, growth was found to cease at a constant value of water activity while that for the less tolerant strain UQM70Y depended on both ethanol concentration and water activity. It is argued that water activity is a more appropriate variable than ethanol concentration for describing some of the nonspecific inhibitory effects apparent in ethanol fermentations. A straightforward method for the calculation of water activity during such fermentations based on the use of solution osmolality is presented.
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  • 12
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Poly(maleic anhydride styrene) graft copolymers of cellulose, pectin polygalacturonic acid salt, calcium polygalacturonate, and starch were prepared and used to immobilize proteins. The cellulose grafts coupled quite appreciable quantities of acid phosphatase, glucose oxidase, and trypsin. However, the general retention of activity was somewhat disappointing. Further investigation with acid phosphatase showed that the amount of enzyme immobilized increased as the amount of anhydride in the graft copolymer increased but no such relationship existed for the enzymic activity. The cellulose graft copolymers were hydrolyzed and it appeared that the carboxyl group aided adsorption of the enzyme. Attempts to couple acid phosphatase using CMC through the free carboxyl groups, created by hydrolysis, gave only a small increase in the extent of protein coupling. However, the unhydrolyzed system gave a useful degree of immobilization of cells of Bacillus stearothermophilus, as did a poly(maleic anhydride/styrene)-cocellulose system. Attempts to improve the activity by using grafts based on other polysaccharide supports met with mixed success. Pectin products were soluble. Polygalacturonic acid products were partially soluble and extremely high levels of enzymic activity were obtained. This was probably due in part to the hydrophilic nature of the system, which also encouraged absorption of the enzyme. Attempts were made to reduce the solubility by using the calcium pectinate salt. Immobilization of acid phosphatase and trypsin resulted in inceased protein coupling but relatively poor activities were attained. A starch based system gave similar results. Calcium polygalacturonate was used to prepare an insoluble graft copolymeric system containing acrylonitrile-comaleic anhydride. The resulting gels gave excellent coupling with acid phosphatase which had a very good retention of activity.
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  • 13
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    Biotechnology and Bioengineering 28 (1986), S. 107-109 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 14
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    Biotechnology and Bioengineering 28 (1986), S. 603-604 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 15
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    Biotechnology and Bioengineering 28 (1986), S. 585-602 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comprehensive review of the microbial kinetics, energetics, and substrate specificities of anaerobic waste-water treatment systems is presented with descriptions of three different state-of-the-art reactor configurations. Each of these reactor systems is intended to enrich different populations of anaerobic acidogens and methan-ogens as a result of design and operational strategies for control of hydrogen and volatile acids. Imposition of these strategies results in different substrate utilization patterns, conversion kinetics, and operational stabilities as are currently being demonstrated in laboratory-scale investigations.
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  • 16
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    Biotechnology and Bioengineering 28 (1986), S. 167-175 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics in fed-batch cultures of acetone butanol fermentation by Clostridium acetobutylicum is compared on glucose, xylose, and mixtures of both sugars. The final conversion yield of sugars into solvents always increases with the sugar feeding rate. At low feeding rates, the sugar concentration in the medium becomes limiting, which results in a slower cellular growth, a slower metabolic transition from an acid to a solvent fermentation and, thus, a higher accumulation of acids. It is only at sufficiently high feeding rates that fed-batch fermentations yield kinetic results comparable to those of batch fermentations. With mixtures of glucose and xylose, because of a maintained low glucose level, both sugars are taken up at the same rate during a first fermentation period. An earlier accumulation of xylose when the fermentation becomes inhibited suggest that xylose utilization is inhibited when the catabolic flux of glucose alone can satisfy the metabolic activity of the cell. Kinetic results with batch and fed-batch fermentations indicate several important features of the regulation of C. acetobutylicum metabolism: an early inhibition by the produced acids; an initiation of solvent formation between 4 and 6 g/L acetic and butyric acid depending on the metabolic activity of the cell; a metabolic transition from acids to solvents production at a rate closely related to the rate of sugar uptake; during solvent production, a reassimilation of acids above a minimal rate of sugar consumption of 0.2 h-1; a final inhibition of the fermentation at a total butanol and acids concentration of ca. 20 g/L.
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  • 17
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    Biotechnology and Bioengineering 28 (1986), S. 631-645 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The feasibility of applying an adaptive control technique to a fermentation process is investigated. The nonlinear, time-variant parameters of a fermentation process were estimated on-line as a series of linearized describing matrices. The matrices were used to update a suboptimal feedback law which controlled the process in real time over the linear region. Experiments were performed on a small-scale fully instrumented fermenter with the online, real-time adaptive control package. Results are presented for both single- and multivariable control, and indicate successful control of yeast cell growth.
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  • 18
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    Biotechnology and Bioengineering 28 (1986), S. 659-662 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A nitrate control system has been devised for the maintenance of stable nitrate concentrations throughout fed-batch fermentations of Corynebacterium glutamicum. The feedback control system was based on the use of a nitrate-ion-selective electrode to directly monitor the nitrate levels in the fermentor and an automatic controller to activate a nitrate feed pump. The electrode which was used for controlling the nitrate level was stable through-out the fermentation period. The apparent maximum specific growth rate, biomass production, protein production, biomass yields on glucose and nitrate, and amino acid production were all optimal at approximately 50mM nitrate.
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  • 19
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    Biotechnology and Bioengineering 28 (1986), S. 646-658 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growth of a hybridoma culture, along with production of monoclonal antibody, was demonstrated over extended periods in polysulfone hollow fiber membrane modules. The molecular weight cutoffs of the membranes were 70,000, 50,000, and 100,000 daltons. The hybridoma cell line, designated 65/26, produced IgG (2b/κ) directed at mouse thymus cell surface antigen, TL.1. Cell growth occurred in the shell space of the reactor, using supplemented RPMI 1640 (20% fetal bovine serum) supplied from a separate reservoir vessel through the hollow fiber lumen. The reservoir contained 125 mL media, which was changed every 4 days. Concentrations of immunoglobulin were determined by an enzyme immunoassay (using protein A and alkaline phosphatase-labeled antibody conjugate). For the 10K, 50K, and 100K hollow fiber membrane modules, the maximum IgG concentrations detected in the 2.5-mL shell space were 47.5-80, 510, and 740 μg/mL, respectively. In the 125-mL reservoir for the 100K hollow fiber membrane module, the IgG concentration was measured at 260 μg/mL These values compare with an IgG concentration of 1 μg/mL when grown in a standard tissue culture flask and 3.2-7.6 μg/mL when grown in 100 ml media in a spinner flask. In addition, 10K and 50K hollow fiber membrane modules were run in a mode that decreased the fetal bovine serum supplement with time. Differences between these systems suggest that it is possible to obtain high IgG accumulation rates, both during and after the exponential growth phase of the hybridoma population.
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  • 20
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    Biotechnology and Bioengineering 28 (1986), S. 1056-1063 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Isoelectric fractionation of the two major proteins of soy is characterized. Fractions are acid precipitated and cen-trifugally collected at pH 6.0 (glycinin) and pH 4.8 (β-conglycinin). Two extremes in the speed of acid addition (rapid, with no mixing, and slow, via acid dialysis, with complete mixing) are compared to determine their effects on the properties of the precipitate. Total protein yield, fraction composition, and aggregate microstructure do not depend significantly on the method of acid addition. Particle size distribution and hindered settling behavior do differ and are explained using a model of aggregate strength. The rapid acid addition produces larger primary particles, because of higher supersaturation, and yields larger aggregates, because of higher interparticle potential and stronger aggregates. Further aggregation in low-shear hindered settling is faster for the slowly precipitated aggregate because few of these bonding sites could survive the high-shear precipitator, whereas more can contribute to aggregation during hindered settling.
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  • 21
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    Biotechnology and Bioengineering 28 (1986), S. 1080-1085 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dehydrogenase activity assay of activated sludge using the redox dye 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride (INT) was investigated. INT-dehydrogenase activity (INT-DHA) was directly proportional to INT dosage and inversely proportional to bio-mass concentration over limited ranges. INT dosages exceeding 2.5m/M were toxic to dilute activated sludge suspensions. INT-DHA was greatest near pH 9, whereas the peak oxygen uptake rate (OUR) occurred at pH 8. Both INT-DHA and OUR varied inversely with sludge age, but INT-DHA was the more sensitive of the two parameters to this variable. Consistently good and highly significant correlations between INT-DHA and OUR of chlorine stressed activated sludge were found at sludge ages ranging 2.2-7.0 days.
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  • 22
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    Biotechnology and Bioengineering 28 (1986), S. 1127-1137 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two microorganisms, E. coli and S. cerevisiae, competing for glucose were maintained in a stable cycle of coexistence by alternating the growth advantage between the two organisms by oscillating the pH in a Chemostat. Pure culture experiments found S. cerevisiae to be insensitive to pH between 5 and 4.3 with a maximum specific growth rate (μmax) of 0.4/hr; while μmax of E. coli decreased from 0.6 h-1 at pH 5 to 0.1 h-1 at pH 4.3. Steady-state and cross-inoculation chemostat runs at a dilution rate of 0.17 h-1 confirmed the expectation that the mixed culture system is unstable at constant pH with E. coli dominating at pH 5 and S. cerevisiae dominating at pH 4.3. Three pH oscillation experiments were performed at D =0.17 h-1 with 1 g per liter glucose feed. The 16 h/16 h cycle was stable for six periods with a stable alternating cycle of E. coli and S. cerevisiae being quickly established. A 18 h pH 5/14 h pH 4.3 cycle was found to be stable with smaller yeast concentrations. A 6 h/6 h cycle was found unstable with yeast washout. Simulation results were compared with these runs and were used to predict the onset of instability. Oscillations of pH can force stable persistence of a competing mixed culture that is otherwise unstable. Thus, varying conditions are experimentally demonstrated to be one explanation for competitive coexistence.
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  • 23
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    Biotechnology and Bioengineering 28 (1986), S. 256-268 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of chemical modification on the initial specific activity, residual activity, and deactivation kinetics of various enzymes is analyzed using a series mechanism. This straightforward multistate sequential model presented is consistent with the enzyme deactivation data obtained from different fields. The enzymes are placed in five different categories depending on the effect of chemical modification on initial specific activity and residual activity or stability. Wherever possible, structure-function relationships are described for the enzymes in the different categories. The categorization provides one avenue that leads to further physical insights into enzyme deactivation processes and into the enzyme structure itself.
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  • 24
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    Biotechnology and Bioengineering 28 (1986), S. 283-287 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 25
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    Biotechnology and Bioengineering 28 (1986), S. 288-293 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wheat straw has been hydrolized with sulfuric acid at 34 and 90°C. The treatment at 90°C yields complete solubilization of hemicellulose to xylose and arabinose without significant amounts of furfural. The influence of acid concentration was studied and the kinetics of the acid-catalyzed hydrolysis has been modeled suggesting a two-consecutive reactions mechanism. This model is useful to explain the different behavior of the concentration of the two main sugars produced. The enhanced cellulose accessibility to enzymatic attack is also reported.
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  • 26
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    Biotechnology and Bioengineering 28 (1986), S. 269-282 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Within the framework of a program aiming to improve the existing extractive recovery technology of fermentation products, the state of the art is critically reviewed. The acids under consideration are propionic, lactic, pyruvic, succinic, fumaric, maleic, malic, itaconic, tartaric, citric, and isocitric, all obtained by the aerobic fermentation of glucose via the glycolytic pathway and glyoxylate bypass. With no exception, it is the undissociated monomeric acid that is extracted into carbon-bonded and phosphorus-bonded oxygen donor extractants. In the organic phase, the acids are usually dimerized. The extractive transfer process obeys the Nernst law, and the measured partition coefficients range from about 0.003 for aliphatic hydrocarbons to about 2 to 3 for aliphatic alcohols and ketones to about 10 or more for organophosphates. Equally high distribution ratios are measured when long-chain tertiary amines are employed as extractants, forming bulky salts preferentially soluble in the organic phase.
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  • 27
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    Biotechnology and Bioengineering 28 (1986), S. 678-683 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Batch and continuous fermentations with Clostridium thermoaceticum (ATCC 39073) using automatic pH control were conducted. The value of μmax obtained from batch fermentation was about 0.14 h-1; acetate yield, which was both growth and non-growth associated, was about 2 mole of acetic acid/mole of glucose, compared with a theoretical maximum value of 3. This low yield, compared with literature data, may be explained by glucose loss through a combination of degradation routes. Continuous fermentation could be sustained for 1600 h or more without contamination problems. Continuous fermentation at high dilution rates indicates that μmax may be well above 0.17 h-1 when fresh feed medium is used. Acetate yields in continuous fermentation were about 77% of theoretical or 2.3 mole of acetic acid/mole of glucose.
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  • 28
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Both the forward and backward reactions of xylose isomerase (Sweetzyme Q) with xylose and glucose as substrates have been studied in terms of kinetics and thermodynamics. The relationship between the two reactions can thus be determined. Much attention has been given to the reaction with xylose as substrate. The optimal conditions of the xylose reaction in terms of pH, buffer, metal ions, substrate concentration, temperature, and ionic strength have been determined. These findings did not differ much from those reported for the glucose reaction. Equilibrium constants for the aldose to ketose conversion were more favorable in the case of glucose. The results obtained with continuous isomerization of xylose in columns packed with either Sweetzyme Q or Taka-Sweet were very similar to those obtained from batch isomerization processes. Particle size had a definite effect on reaction rate, which indicates that diffusion limitations do occur with the immobilized enzyme particles. Heat stability of Sweetzyme Q was good with t1/2 of 118, 248, and 1200 h at 70, 55, and 40°C, respectively. A novel method for the separation of xylose-xylulose mixtures with water as eluant on a specially prepared Dowex 1 × 8 column was developed. This technique has the capability of producing pure xylulose for industrial or research applications. A writ for a patent regarding this technique is at present prepared.
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  • 29
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    Biotechnology and Bioengineering 28 (1986), S. 711-717 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alcoholic fermentations of starch hydrolysate by two different yeast strains, Saccharomyces cerevisiae(var. Vinal) and Saccharomyces oviformis(IMAP 383), have been studied in batch runs. In order to evaluate the different inhibition phenomena due to both substrate and product, a new kinetic equation is suggested.
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  • 30
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    Biotechnology and Bioengineering 28 (1986), S. 700-710 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous cultures of Saccharomyces cerevisiae are known to exhibit oscillatory behavior in the oxidative region. Important findings of a series of experiments conducted to identify the causes for initiation of and the means for elimination of oscillations in these cultures are reported in this paper. These oscillations are seen to be connected to the growth kinetics of the microorganism and are induced at very low glucose concentrations and at dissolved oxygen (DO) levels that are neither high nor low (DO values between 20 and 78% air saturation at a dilution rate of 0.2 h-1 and pH of 5.5 at 30°C). The oscillatory behavior is encountered over a range of dilution rates (0.09-0.25 h-1 at 30°C for pH = 5.5 and DO = 50% air saturation). The oscillations can be eliminated by raising the DO level above a critical value or by lowering the DO level below a critical value.
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  • 31
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    Biotechnology and Bioengineering 28 (1986), S. 728-735 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comparison of the relative performance of production techniques using coenzyme or cofactor electrochemical regeneration demonstrates the superiority of those processes in which the enzymatic reaction and the regeneration are conducted in the same reactor as opposed to those in which the reaction and regeneration are separated. For the former type of reactor, a method of calculation is proposed. This method is based on the solution of equations which describe the phenomena in modules representing three areas: the surface of the electrode, a layer where occur simultaneously the transport of material and the enzymatic reaction, and the bulk of the solution. This method is suggested for three types of reactor: those in which an enzyme solution is held close to an electrode by a semipermeable membrane, those in which an enzyme-charged membrane is in contact with an electrode, and those in which the enzyme is in solution in the vessel into which the electrode is dipped.
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  • 32
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    Biotechnology and Bioengineering 28 (1986), S. 718-727 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The development of granular sludge in thermophilic (55°C) upflow anaerobic sludge blanket reactors was investigated. Acetate and a mixture of acetate and butyrate were used as substrates, serving as models for acidified waste-waters. Granular sludge with either Methanothrix or Methanosarcina as the predominant acetate utilizing methanogen was cultivated by allowing the loading rate to increase whenever the acetate concentration in the effluent dropped below 200 and 700 mg COD/L, respectively. The highest methane generation rates, up to 162 kg CH4-COD/m3 day, or 2.53 mole CH4/L day, were achieved at hydraulic retention times down to 21 min, with granules consisting of Methanothrix. The formation of Methanothrix granules did not depend on the type of seed material, nor on the addition of inert support particles. The growth of granules proceeded rapidly with adapted seed material, even when the reactors were inoculated with low concentrations. With mesophilic seed materials growth of granules took much longer. Thermophilic Methanothrix granules strongly resemble mesophilic granules of the “filamentous” type. Some factors governing the thermophilic granulation process are discussed.
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    Biotechnology and Bioengineering 28 (1986), S. 741-746 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Biotechnology and Bioengineering 28 (1986), S. 736-740 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bovine trypsin was crosslinked to human serum albumin (HSA) with glutaraldehyde to form soluble and insoluble copolymers. The physical and kinetic properties of trypsin and trypsin-HSA polymers were compared. Trypsin was heat labile, retaining only 24% of its enzymic activity after heating for 5 min at 60°C. In contrast, under the same condition both the soluble and insoluble trypsin-HSA polymers showed enhanced resistance to heat in-activation, retaining 81 and 100% of their original activities, respectively. The trypsin-HSA polymers also showed shifts in pH optima, an increase in activation energy, and a broadening of their pH stability profiles.
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    Biotechnology and Bioengineering 28 (1986) 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 28 (1986), S. 1277-1285 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general model of enzyme deactivations involving unimolecular processes is introduced. For most mechanisms of this type, the parameters of the general model can be expressed in terms of actual physical parameters. The number of physical parameters that can be determined from the deactivation data cannot exceed the number of independent constants in the general model. When there is an excess of physical parameters, then some parameters must be determined from independent methods of analysis. If this is not possible, then some parameters must be left as lumped parameters or global parameters. The general form of the model can be useful in determining the number of independent, potentially active forms of the enzyme present during deactivation. Some exceptions to the general model are due to higher-order processes such as dissociation, autolysis, and biological contamination.
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    Biotechnology and Bioengineering 28 (1986), S. 756-760 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 28 (1986), S. 761-763 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 28 (1986) 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 28 (1986), S. 764-767 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Biotechnology and Bioengineering 28 (1986), S. 769-784 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The morphology of yeast cells as it is affected by the glycosidic linkages of constituent glucan was studied. Four different strains of Saccharomyces cerevisiae were studied. A cell wall matrix particle representing the intact original morphology and composed entirely of β-glucan was prepared. Using prepared cell wall glucan particles, the morphology and cell wall matrix structure were examined. Genetic modification of the cell wall structure during growth results in the alteration of the shape and hydrodnamic volume of the intact cell wall particles. The shape and hydrodynamic volume of the cell wall particles can also be modified by in vitro chemical and enzymatic treatment. The shape factor and hydrodynamic volume of the whole glucan cell wall matrix particles were evaluated quantitatively using a rheological analysis. An increased degree of β(1 → 6) cross-linking in the cell wall matrix induces a nearly 2-fold increase in the shape factor and a 10-fold increase in the compression modulus of the glucan particles. The disruption of β(1 → 6) glycosidic cross-linking causes the particles to swell by up to 18% of their original volume. This was used as a strategy to isolate a yeast mutant with a high β(1 → 6) glycosidic content in the cell wall glucan.
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    Biotechnology and Bioengineering 28 (1986), S. 1310-1317 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two instruments were developed to mechanize the handling of anaerobic microorganisms for microbial mutant isolation. The instruments automatically dispense liquid or agar medium to large and small 96-well platesand petridishes. Protocols were developed for inoculating different microorganisms, and calibration curves of number of areas or wells inoculated versus cell concentration were prepared for bacteria, yeast and fungi (spores). Experiments with yeast auxotrophic mutants and fungal spores showed that microbe inoculation follows Poisson statistics in distributing a single microorganism per inoculation point. The isolation and identification of Yarrowia lipolytica auxotrophic, morphological, and temperature-sensitive or tolerant mutants demonstrated the use of the instruments for microbial screening.
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  • 43
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    Notes: The problem of dilute solvent concentration in butanol-acetone fermentations can be solved by using reverse osmosis to dewater the fermentation liquor. Polyamide membranes have a potential application in a butanol-acetone fermentation and exhibited rejection rates as high as 98%. Optimum rejection of butanol in the fermentation liquor occurred at recoveries of 20-45%. Flux ranged from 0.05 to 0.6 L m-2 min-1.
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  • 44
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    Biotechnology and Bioengineering 28 (1986), S. 792-801 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Material balances for pentosan, lignin, and hexosan, during steam-explosion pretreatment of aspenwood, showed almost quantitative recovery of cellulose in the water-insoluble fraction. Dilute acid impregnation resulted in more selective hydrolysis of pentosan relative to undesirable pyrolysis, and gave a more accessible substrate for enzymatic hydrolysis. Thermocouple probes, located inside simulated aspenwood chips heated in 240°C-saturated steam, showed rapid heating of air-dry wood, whereas green or impregnated wood heated slowly. Small chips, 3.2 mm in the fiber direction, whether green or airdry gave approximately equal rates of pentosan destruction and solubilization, and similar yields of glucose and of total reducing sugars on enzymatic hydrolysis with Trichoderma harzianum. Partial pyrolysis, destroying one third of the pentosan of aspenwood at atmospheric pressure by dry steam at 276°C, gave little increase in yield of reducing sugars on enzymatic hydrolysis. Treatment with saturated steam at 240°C gave essentially the same yields of glucose and of total reducing sugars, and the same yields of butanediol and ethanol on fermentation with Klebsiella pneumoniae, whether or not 80% of the steam was bled off before explosion and even if the chips remained intact, showing that explosion was unnecessary.
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  • 45
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    Biotechnology and Bioengineering 28 (1986), S. 811-817 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Removal and modification of southern red oak hemicelluloses and lignin in a 0.05%(w/v) sulfuric acid hydrolysis were investigated. The hydrolysis profile was to raise the reaction from room temperature to 150°C for in 38 min and to extend the hydrolysis at 150°C for 1 h. At the end of the hydrolysis, 25.5% of red oak components were dissolved, of which 58% was xylose and 17% lignin. As the hydrolysis proceeded from room temperature to 150°C, a part of red oak xylan was removed to yield an oligomer fraction having maximal yield and average molecular weight of 3460 at 150°C. This fraction and the bulk xylan extracted during the first 30 min at 150°C were further degraded to give a lower molecular weight oligomer fraction, of which the yield and average molecular weight (2610) were highest at the end of the bulk removal of xylan. Red oak lignin, syringyl and guaiacyl units in particular, was increasingly removed with the progress of the hydrolysis. Lignin derivatives and a part of red oak extractives soluble in the hydrolysate were identified.
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    Biotechnology and Bioengineering 28 (1986), S. 818-823 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article concerns the development of a simple yet effective procedure for optimizing the design of a reactor system employing CSTRs in series. The basic approach used in this work was to translate the problem of reactor design to a mathematical programming model. The resulting model was then solved by dynamic programming. The procedure was tested on an IBM 3033 computer and an IBM PC-compatible machine, the CORONA PC-II microcomputer. The results of this study indicate that the optimization procedure developed is very effective.
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  • 47
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    Biotechnology and Bioengineering 28 (1986), S. 1742-1752 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mixed culture of Saccharomyces cerevisiae and Escherichia coli was established in a stable coexistence steady state in a chemostat under constant operating conditions. The species competed for glucose, the growth-limiting resource, and produced acetate and ethanol. The acetic acid was shown to be very inhibitory to E. coli in pure culture at pH 5 while ethanol inhibition was only marginal. No significant inhibition of S. cerevisiae growth was observed by either acetate or ethanol. Pure culture parameters were measured and used in the analysis. Linearized stability analysis for the case when both organisms produce the inhibitor showed that a transition through three stable outcomes was possible as the feed concentration is lowered. Experimental studies verified these predictions, and successive transitions from a yeast growth steady state, to a coexistence steady state, and to an E. coli growth steady state were obtained by lowering the glucose concentration in the feed from 10 to 5 to 2.5 g/L, respectively. This dynamic behavior is distinct from the outcomes of other competition-inhibition combinations and experimentally demonstrates for the first time that coexistence is possible due to substrate competition and product inhibition.
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  • 48
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    Notes: The utilization of mixtures of methanol (C1) and glucose (C6) of different composition by the methylotrophic yeast Hansenula polymorpha was studied in carbon-limited chemostat culture. For all mixtures tested a similar utilization pattern was observed: At low dilution rates both carbon sources were utilized simultaneously, but at high dilution rates the cells used glucose only and the unutilized methanol accumulated in the culture medium. When grown with C1 only, the cells exhibited a critical dilution rate Dc(C1) of 0.19 h-1, but when C1-C6 mixtures were used as the carbon and energy substrate, the yeast was able to completely utilize C1 at dilution rates considerably higher than Dc(C1). The dilution rate at which the transition from C1-C6 growth to C6 growth occurred (Dt) was strictly dependent on the composition of the C1-C6 mixture in the feed, and Dt increased with decreasing proportions of C1 in the mixture. During mixed substrate growth the formation of biomass from the two substrates was additive. The results reported indicate that the utilization of C1-C6 mixtures and hence Dt in H. polymorpha are subject to two different regulatory regimes. When the cells were growing with C1-C6 mixtures containing more than 60% C1, the transition form C1-C6 to C6 growth was most probably influenced by the maximum C1 oxidizing capacity of the cells, whereas for growth with mixtures containing less than 40% C1, a growth rate of 0.28-0.30 h-1 seemed to be the limiting barrier for the simultaneous utilization of the components of the binary carbon and energy substrate mixture.
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    Biotechnology and Bioengineering 28 (1986), S. 1769-1773 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A relatively simple and inexpensive anaerobic calorimeter was designed and evaluated by using a Hy-Cal Engineering BI-7 bidirectional heat-flux sensor to measure heat output from magnetically stirred I-L flask fermentations. The production of ethanol and cumulative heat output by Zymomonas mobilis were both linearly proportional to glucose concentrations up to 160 g/L.
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    Biotechnology and Bioengineering 28 (1986), S. 1774-1779 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The irradiation with visible light of a photosensitizer dye like methylene blue was used to regenerate by electron transfer the oxidized form of a pyridine nucleotide coenzyme (NAD+). The process has been studied on a common enzymatic reaction: ethanol oxidation by alcohol-NAD+ oxidoreductase immobilized on polyacrylamide gel or porous glass balls. In the experimental conditions used, the initial NAD+ recycling rates were 2.33 × 104 cycles/h (polyacrylamide) and 3 × 104 cycles/h (glass balls). A total number of 49.5 × 104 cycles was obtained for 13 runs of 2 h. The enzyme immobilization strongly increased its stability: after 28 days at 20°C, the residual activity was 25% of the initial value.
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    Biotechnology and Bioengineering 28 (1986), S. 1761-1768 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of ethanol from starch by a coimmobilized mixed culture system of aerobic and anaerobic microorganisms in Ca-alginate gel beads was investigated. The mold Aspergillus awamori was used as an aerobic amylolytic microorganism and an anaerobic bacterium, Zymomonas mobilis, as an ethanol producer. By controlling the mixing ratio of the microorganisms in the inoculum size, a desirable coimmobilized mixed culture system, in which the aerobic mycelia grew on and near the oxygen-rich surface of the gel beads while the anaerobic bacterial cells mainly grew in the oxygen-deficient central part of the gel beads, was naturally established under the aerobic culture conditions, and ethanol could be directly produced from starch by the system. The ethanol productivity by the system in flask culture was particularly affected by the shear stress (dependent on the shaking speed) which controlled the mycelial growth on the surface of the gel beads. Under optimum culture conditions in the flask culture, the glucose produced was instantly consumed, and was not observed in the culture broth; the final concentration of ethanol produced from 100 g/L starch was 25 g/L and the yield coefficient for ethanol, Ypls, was 0.38. The ethanol productivity by the coimmobilized mixed culture system was compared with those by other various culture systems and the advantages of the system were clarified.
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    Biotechnology and Bioengineering 28 (1986), S. 1780-1793 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The modification and principle of a novel heat flux calorimeter for the in situ, on-line measurement of the heat generated during microbial growth is described. Data concerning the physical characterization of the calorimeter as a fermentor, including stability and sensitivity of the heat signal, are presented. The calorimeter has been successfully applied to the study of the aerobic batch culture of Escherichia coli W on glucose under carbon and nitrogen limitation. A direct correlation between growth and heat evolution was obtained. Quantitative analysis of the data suggests that the new calorimetric technique could be used for monitoring growth and specific metabolic events, for convenient medium optimization, and as a basis for a novel fermentation process control system.
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    Biotechnology and Bioengineering 28 (1986), S. 1801-1808 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A predictive model was developed to estimate the dewatering characteristics of waste-activated sludges. This model utilizes the COD-nitrogen ratio of the wastewater and the organic loading rate of the process to predict sludge filterability in terms of specific resistance. A completely mixed, continuous flow secondary treatment process with solids recycle was used for the cultivation of activated sludges. The sludge wasted from this process was used in Buchner funnel specific resistance determinations. The basic concepts involved in the development of the model were supported by sludge carbohydrate, protein, and surface charge data.
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    Notes: An improved method is presented for estimating rejection coefficient-molecular weight relationship of an ultrafiltration membrane for a polydisperse chain polymer. It is based on the basic idea using gel permeation chromatography originally developed by Cooper and Van Derveer. The method, in which peak spreading of an elution curve of the polymer was taken into consideration, is available for evaluating the relationship over a wide range of the molecular weight through only one experiment in analyses of the retentate and filtrate.
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    Biotechnology and Bioengineering 28 (1986), S. 1611-1614 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple procedure for the entrapment of enzymes in nylon-reinforced cellulose triacetate fibers and the fabrication of reusable enzyme brushes using such fiber bristles for the analytical determination of unknown samples have been described. As an example, enzyme brushes of lactate dehydrogenase were fabricated and were repeatedly employed for the determination of pyruvic acid in clinical samples in place of soluble enzymes. The above brush method compared well with that of wet enzymic analysis of pyruvate in clinical samples in accuracy, sensitivity, and reproducibility. The device also proved to be easy to handle, use, and reprocess for repeated analyses.
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    Biotechnology and Bioengineering 28 (1986), S. 988-995 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to predict the potential benefit associated with mixing devices designed to introduce periodic light modulations in dense cultures of microalgae, it is necessary to develop a quantitative understanding of the relationship between the frequency of the modulations and the resulting photosynthetic efficiency enhancement. To explore this relationship, the photosynthetic rate of cells of Phaeodactylum tricornutum from a dense steady state culture was determined as a function of modulation frequency, intensity of light received, and the proportion of the total cycle period during which the cells were illuminated. At high flash frequencies, the photosynthetic rate was determined by the average intensity received by the cells (full light intensity integration), while at low frequencies the cells responded to the instantaneous intensity (no light intensity integration). Full integration was approached asymptotically with increasing flash frequency. The frequency response could be described by a rectangular hyperbola, and the parameters of this hyperbola were nearly independent of the illumination intensity and the flash proportion. The saturation constant of the hyperbola, at which the response is one-half of the maximum, was 0.67 Hz.
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    Biotechnology and Bioengineering 28 (1986), S. 1007-1013 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The time course of the peroxidative bromination of propylene accompanied by in situ generation of hydrogen peroxide by glucose oxidase was examined to improve the productivity of propylene bromohydrin. To prevent the rapid inactivation of lactoperoxidase by excess hydrogen peroxide, it was effective to use lactoperoxidase in large excess as compared with glucose oxidase, and to raise the concentration of bromide ion. However, the rate of glucose consumption was lowered at high concentrations of bromide ion, and at higher mole fraction of oxygen as compared with propylene in the gas mixture. Therefore, it seemed that for the favorable production of bromohydrin there existed the optimal conditions for the concentration of bromide ion and for the composition of oxygen-propylene gas mixture. Such kinetic behaviors of the sequential enzymatic reactions were explained by a mechanism involving free hypobromous acid as a reactive intermediate. Furthermore, the stability of the coimmobilized enzymes with k-carrageenan gels was investigated in continuous operations. The half-life of the enzymes was ca. 60 h for the production of propylene bromohydrin.
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  • 58
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    Biotechnology and Bioengineering 28 (1986), S. 996-1006 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Widely applied selection strategies for plasmid-containing cells in unstable recombinant populations are based upon synthesis in those cells of an essential, selection gene product. Regular partitioning of this gene product combined with asymmetric plasmid segregation produces plasmid-free cells which retain for some time the ability to grow in selective medium. This theory is elaborated here in terms of a segregated model for an unstable recombinant population which predicts population growth characteristics and composition based upon experimental data for stable strain growth kinetics, plasmid content, and selection gene product stability. Analytical solutions from this model are compared with an unsegregated phenomenological model to evaluate the effective specific growth rate of plasmid-free cells in selective medium. Model predictions have been validated using experimental growth kinetics and flow cytometry data for Saccharomyces cerevisiae D603 populations containing one of the plasmids YCpG1ARS1, YCpG1ΔR8, YCpG1ΔR88, YCpG1ΔH103, YCpG1ΔH200, pLGARS1, and pLGSD5. The recombinant strains investigated encompass a broad range of plasmid content (from one to 18 plasmids per cell) and probability α of plasmid loss at division (0.05 ≤ α ≤ 0.42). Experimental data for all strains considered is inconsistent with the hypothesis that plasmid-free cells are unable to grow in selective medium. For a given value of a, the fraction of plasmid-containing cells in the population decreases with increasing plasmid content and increases for less stable selection gene products. This conceptual framework and mathematical model will aid in strain development for greater effective stability.
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  • 59
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    Biotechnology and Bioengineering 28 (1986), S. 1014-1023 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biomass of the blue-green alga Spirulina maxima was converted to methane using continuous stirred tank digesters with an energy conversion efficiency of 59%. Digesters were operated using once-a-day feeding with a retention time (θ) between 5 and 40 days, volatile solid concentrations (Sto) between 20 and 100 kg VS/m3, and temperatures between 15 and 52°C. The results indicated a maximum methane yield of 0.35 m3 (STP)/kg VS added at θ 30 days and Sto 20 kg VS/m3. Under such conditions, the energy conversion of the algal biomass to methane was 59%. The maximum methane production rate of 0.80 m3 (STP)/m3 day was obtained with θ= 20 days and S = 100 kg VS/m3. The mesophilic condition at 35°C produced the maximum methane yield and production rate. The process was stable and characterized by a high production of volatile acids (up to 23, 200 mg/L), alkalinity (up to 20, 000 mg/L), and ammonia (up to 7000 mg/L), and the high protein content of the biomass produced a well buffered environment which reduced inhibitory effects. At higher loading rates, the inhibition of methanogenic bacteria was observed, but there was no clear-cut evidence that such a phenomenon was due to nonionized volatile acids or gaseous ammonia. The kinetic analysis using the model proposed by Chen and Hashimoto indicated that the minimum retention time was seven days. The optimum retention time increased gradually from 11 to 16 days with an increase in the initial volatile solid concentration. The kinetic constant K decreased with the improvement in the digester performance and increased in parallel with the ammonia concentration in the culture media.
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  • 60
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    Biotechnology and Bioengineering 28 (1986), S. 1044-1055 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cybernetic models, developed earlier by the authors, have been evaluated experimentally for the growth of Klebsiella oxytoca in batch cultures using mixed substrates from glucose, xylose, arabinose, lactose, and fructose. Based entirely on information procured from batch growth on single substrates, the models accurately predict without further parameter fitting, diauxic growth on mixed substrates, automatically predicting the order in which the substrates are consumed. Even triauxic growth on a mixture of glucose, xylose, and lactose is predicted by the model based on single substrate data. Growth on glucose-fructose mixtures appears to need a slightly modified strategy for cybernetic variables.
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  • 61
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    Biotechnology and Bioengineering 28 (1986), S. 1064-1071 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been cited in the literature on hollow fiber systems that pressure gradients persist, and the transmembrane flux of the hollow fiber system is dependent on the pattern of the pressure gradients. The pattern can be used to its advantage in immobilized enzyme systems. However, with immobilized living cell systems, the pressure gradients lead to a nonuniform environment within the hollow fiber cartridge and not necessarily favorable results. This article provides pertinent pressure-drop data on hollow fiber cartridges which are in flow configurations typical of immobilized cell culture work. The results illuminate operational problems that may arise in the culture of either anchorage dependent or independent cells. Possible solutions with crossflow systems are suggested.
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  • 62
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    Biotechnology and Bioengineering 28 (1986), S. 1690-1698 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Yeast nucleoproteins were chemically phosphorylated with phosphorus oxychloride (POCL3). Studies using 31P nuclear magnetic resonance (NMR) spectroscopy, stability to pH and lysine estimation all indicated that the ∊-amino group of lysine was the principal functional group phosphorylated. Phosphorylation of ca. 30% of the lysine residues resulted in removal of more than 85% of contaminant ribonucleic acid from protein precipitated at pH 4.2. Phosphorylation did not alter the amino acid composition of yeast proteins and was reversible under acidic conditions. Based on the data, a method for the preparation of phosphorylated yeast protein with low levels of nucleic acid is proposed.
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  • 63
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    Biotechnology and Bioengineering 28 (1986), S. 1672-1689 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A structured mathematical model for cellular metabolism in Escherichia coli has been extended to encompass the mechanistic structure surrounding the kinetics and control of transcription and translation. The dependence of transcription on RNA polymerase and the mechanism of translation initiation have been explicitly included. This model correctly simulates cell growth, cell composition, and the timing of chromosome synthesis as a function of extracellular substrate concentration for glucose-limited balanced growth. Simulation results for the subpopulation of RNA polymerase engaged in transcription and for the distribution of this subpopulation among different promoter sites agree closely with experimental findings, as do calculated estimates of the active ribosomal fraction. In addition, the existence of an antitermination system for transcription of stable RNA operons is supported by model results. This model should provide a useful framework for investigating metabolic perturbations to E. coli, such as those resulting from insertion of extra-chromosomal vectors into the cells.
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  • 64
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    Biotechnology and Bioengineering 28 (1986), S. 1166-1171 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The adsorptive behavior of cells of Acetobacter aceti, ATCC 23746, on DEAE-, ECTEOLA-, TEAE-, and DEHPAE-cellulose ion exchangers in a modified Hoyer's medium at 30°C was investigated. The maximum observed adsorption capacities varied from 46 to 64 mg dry wt/g resin. The Langmuir isotherm form was used to fit the data, since the cells formed a monolayer on the resin and exhibited saturation. The equilibrium constant in the Langmuir expression was qualitatively correlated with the surface charge density of the resin. The adsorption was also “normalized” by considering the ionic capacities of the resins. The exceptionally high normalized adsorption capacity of ECTEOLA-cellulose, 261 mg dry wt/meq, may be explained by an interaction between the cell wall and the polyglyceryl chains of the exchanging groups in addition to the electrostatic effects. The effect of pH on the bacterial adsorption capacity of ECTEOLA-, TEAE-, and phosphate-cellulose resins was studied and the pl of the bacteria was estimated to be 3.0.
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    Biotechnology and Bioengineering 28 (1986), S. 1191-1199 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In relation to the input-output characteristics of enzymatic reactions in the cellular metabolism and biochemical reactors, the validity of the quasi-steady-state and transfer-function representations of reaction velocity has been examined for a basic Michaelis-Menten reaction employing computer simulation, that is, numerical integration of the rate equation. The well-known S-v relationship (relationship between substrate concentration and reaction velocity)derived on the quasi-steady-state assumption is found to be in general a good approximation to the actual velocity throughout the temporal progress of the reaction. The validity of the approximation depends on a ratio of the Michaelis constant to the total enzyme concentration in the reaction system rather than on the individual rate constants. A transfer-function representation is derived on assuming an exponential change in the reaction velocity for the indicial response to the substrate influx rate. The representation has a wider valid region with a decrease in influx rate than with an increase in the influx rate. The validity is most dependent on a ratio of total enzyme concentration to the steady-state concentration of the substrate. The analysis of the linear sensitivity of the reaction velocity to rate constants reveals that the characteristics of these valid representations in systems analysis change according to the phase of the reaction.
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    Biotechnology and Bioengineering 28 (1986), S. 1206-1212 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model has been developed for the process of extractive fermentation. The model rigorously treats the material balance, reaction kinetics, and liquid-liquid equilibrium relationships. Convergence is promoted through use of the Quasi-Newton Method. Extractive fermentation is particularly attractive for those bioreactions where the cell growth and product formation is inhibited by the product or other secondary cellular products. The model is illustrated for the production of ethanol. The results show an increase in specific productivity and the ability to process a more concentrated feed. However, volumetric productivity is reduced in the presence of a low capacity solvent.
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    Biotechnology and Bioengineering 28 (1986), S. 1421-1431 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The optimal substrate feeding policy for the fed batch fermentation which is governed by product and substrate inhibited kinetics is presented. The conjunction point between nonsingular and singular arcs and the feeding policy along the singular arc are derived analytically in terms of the concentrations of substrate and product and the liquid volume. Thus, it is possible to determine the feeding rate by monitoring the state variables (i.e., closed loop control). As a specific example, an optimization study of the fed batch fermentation for ethanol production by Saccharomyces cerevisiae is presented. It is shown that the optimal feeding patterns are heavily dependent upon the initial conditions. The point selectivity provides the guideline for predicting the optimal feeding patterns and explaining the results of rigorous mathematical analysis.
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    Biotechnology and Bioengineering 28 (1986), S. 1555-1563 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sugar-limited batch growth of Dioscorea deltoidea and Catharanthus roseus plant cell cultures was studied in a 14-L stirred tank fermentor. With dissolved oxygen concentration monitored and maintained at nonlimiting levels, growth rates and ratios of dry weight to fresh weight were found to be strongly influenced by sugar concentration. Linear relationships between respiration rate and growth rate were observed, and respiration rate was found to drop to a maintenance level after sugar had been fully depleted from the medium. Diosgenin biosynthesis by D. deltoidea was shown to be independent of growth rate. Ajmalicine biosynthesis in C. roseus was negligible during sugar-limited growth but was induced by inoculation into an 80-g/L glucose solution.
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  • 69
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    Biotechnology and Bioengineering 28 (1986), S. 1544-1554 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comprehensive kinetic study of the acid hydrolysis of concentrated brewing bagasse slurries was performed. The use of the simple series reaction model was found to be suitable when a “heterogeneous correction” (pseudosubstrate-inhibition) is taken into account in slurries with low liquid-to-biomass ratios. Rate constants are shown to be dependent not only on temperature and acid concentration but essentially also on the initial biomass concentration. Actual rate constants, activation energies, and acid and substrate reaction orders are reported for xylan, arabinan, and α-glucan acid saccharification. There is a threshold acid loading necessary to overcome the 80% conversion, but no threshold has been found to overcome the “neutralizing” property of cellulosic materials. Reversible acid capture from brewing bagasse has been postulated. The highest monosccharide concentration into hydrolyzates has been found (65 g/L) after 10 h treatment, but economic considerations led us to treat a mean-concentrated slurry (156 g/L) with 0.3M H2SO4 at 96°C, thus obtaining 45.5 g/L monosaccharides in 5 h with 50% less furfural content. After pH regulation only, growth of Clostridium acetobutylicum has been obtained, although complete sugar comsumption has not been achieved. Experiments are now underway to reach complete digestion and to investigate the increase of enzymic accessibility into residual substrate rich in cellulose.
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    Electrophoresis 7 (1986), S. 54-55 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The interpretation of nucleic acid sequences on polyacrylamide gels is often made difficult due to “smiles”. We have devised a simple modification for commonly used electrophoresis systems to eliminate this problem.
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    Electrophoresis 7 (1986), S. 56-57 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Lateral streaking or bending in vertical one-dimensional slab gel electrophoresis can be completely avoided if a comb-gel made up in electrophoresis buffer is placed on top of the stacking gel or sample gel.
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    Electrophoresis 7 (1986), S. 58-58 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 73
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    Topics: Biology , Chemistry and Pharmacology
    Notes: The level of genetic variation revealed by two-dimensional electrophoresis of proteins from seedlings of two wheat lines strongly depends on the technical procedures. Improvements in extraction and electrophoresis procedures relative to earlier experiments on the same material led to a significant increase in the genetic variation revealed: 15.2 % instead of 6.7 % of the spots were genetically variable. The improved procedure is based on (i) precipipation of proteins from wheat seedlings with trichloroacetic acid and acetone, (ii) solubilization of the proteins with a solution containing urea, potassium carbonate and sodium dodecyl sulfate, (iii) isoelectric focusing in an optimized pH gradient, obtained with a mixture of carrier ampholytes (Pharmalyte and Servalyt), and (iv) running elecrophoresis in the second dimension on gels with increased surface.
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    Electrophoresis 7 (1986), S. 107-113 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In order to survey changes in accumulation of several hundred proteins during the naturally synchronous nuclear division cycle of Physarum polycephalum, we have developed methods for analyzing two-dimensional (2-D) gel electrophoretograms using the general image processing system developed by the Spatial Data Analysis Laboratory at Virginia Tech. In this paper we describe fast and accurate methods for removing non-homogeneous background intensity from a 2-D gel image, for resolving overlapping protein spots, and for estimating the total integrated intensity in a protein spot by Gaussian modeling.
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    Topics: Biology , Chemistry and Pharmacology
    Notes: A method is described which allows the preparation of retinae, laminae, opticallobes, protocerebrum and proboscis of single heads of Drosophila. The protein content of these tissues was examined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Coomassie Brilliant Blue R-250 and glycoprotein staining. A catalog of 39 major proteins or protein subunits was obtained. Their relative proportions were determined quantitatively for the different tissues from Drosophila wildtype strains AS and C-S as well as the mutant sevLY3.
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    Electrophoresis 7 (1986), S. 221-226 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A compact device, capable of being clipped onto the end of a 3 mm thick analytical polyacrylamide slab gel, has been developed for the collection of resolved protein zones as they elute from the end of the gel. Its unique feature is that eluted proteins were collected between two polyacrylamide-embedded paper membranes and removed either by continuous or intermittent buffer elution. Because of this direct coupling to large gels identical to those used for analytical electrophoresis, protein zones were obtained with high resolution. The method was applicable to non-denaturing cathodic and anodic electrophoresis, as well as sodium dodecyl sulfate electrophoresis. Medium-scale quantities (up to 10 mg/cm2 cross-sectional area) of protein were fractionated in as little as 4 h with high recoveries.
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  • 77
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Electrofocusing on diagonal immobilized pH gradients was designed to combine high field strength with a flat pH gradient over a wide pH range, circumventing the need for extremely high voltage in long, conventionally oriented focusing gels. The technique was found to be applicable at 500 V cm-1 to gels of 35 cm length of a flat pH gradient with a predicted pH range of 3.8 to 9.8, allowing for a focusing time of 2 h. Note that the equivalent flat pH gradient gel of 25 cm length at the same field strength would require application of 12 500 V. However, preliminary results indicate that the theoretically expected improvement in resolution due to high field strength does not materialize. This may be due to a distorted electric field caused by non-uniform conductance features inherent in the method and by the passage of the current through the isoelectric protein zones.
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    Electrophoresis 7 (1986), S. 235-236 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The sensitivity for protein detection after isoelectric focusing can be enhanced using a newly developed applicator strip with a concentration effect. This effect is achieved with funnel-shaped slots, which are placed parallel to the pH gradient. Furthermore, sample volumes varying from 1-90 μL can be applied without distortion to the pH gradient. A comparison with other commercially available applicator strips was undertaken using the phosphoglucomutase system.
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    Electrophoresis 7 (1986), S. 239-239 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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    Electrophoresis 7 (1986), S. 239-239 
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    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 81
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Immobilized pH gradient (IPG) slab gels are conventionally formed by use of two-chamber gradient mixers on pH-neutralized Immobiline mixtures, co-polymerization of the gradient of Immobilines with acrylamide at 50 °C, washing and drying of the gel to its original weight followed by pre-electrophoresis before applying the sample. This tedious procedure was replaced by one using gradient formation by pump, eliminating pH neutralization of the monomer mixture, substituting polymerization at 50 °C for one at the temperature of electrophoresis (10 °C in this study) and omitting washing and drying of the gel prior to use. Carrier ampholyte (CA) containing IPG gels were formed in the same way except that CAs were added to the polymerization mixture. Pre-electrophoresis of IPG gels, formed by either the conventional or the simplified procedure, was found to be detrimental to the IPG patterns of proteins. The simplified procedure also allowed one to conduct IPG electrophoresis in gel tubes, eliminating lateral zone diffusion.
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  • 82
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Human genomic DNA probes labeled by nick translation with biotin 11-UTP were successfully used to identify single copy restriction fragment length polymorphisms following electrophoresis and Southern blotting onto nylon membranes. Two human probes found on chromosome 21 were used, each of which demonstrated polymorphisms using two separate restriction endonucleases. Compared to isotopic labeling of probes the biotin labels are safer, faster and more economical. The detection method of streptavidin-biotin-alkaline phosphatase permitted phenotyping in a matter of hours after hybridization of the probe to the human DNA fragments.
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  • 83
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    Topics: Biology , Chemistry and Pharmacology
    Notes: A program in BASIC Microsoft for a microcomputer is described for the analysis of electrophoretic patterns obtained by polyacrylamide gel electrophoresis. The program enables a rapid calculation of relative molecular masses and designs three types of graphs: the protein pattern, the linear representation of molecular masses and the linear regression curve calculated from several standard proteins. The application of this program for the study of serotypes A and B of the yeast Candida albicans is shown.
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    Electrophoresis 7 (1986), S. 323-326 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Superposed miniature agarose slab gels and relatively small plasmids were used to evaluate the DNA topoisomerase I activity associated with the chromatin of normal human fibroblasts at three different in vitro population doubling levels. Results obtained in a short period of time with a single miniature electrophoresis unit confirm an increase in DNA-relaxing enzyme activity with cell age.
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    Electrophoresis 7 (1986), S. 339-341 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Pea protoplast dielectrophoretic coefficients were measured in AC fields of different frequencies applied between concentric cylindrical metal electrodes, outer and inner radii, 0.24 mm and 1 mm, respectively. The values for 0.5 M mannitol solutions are: (6.0, 1.0, 5.6, 16.0 and 17.8) X 10-24Fm2 at frequencies 0.05, 0.1, 0.6, 1 and 8 MHz, respectively. The specific polarizabilities (dielectrophoretic coefficients per unit volume of the protoplasts) are: (5.0, 0.7, 4.0, 12.0 and 13.0) X 10-10Fm-1, respectively. Below 10 kHz dielectrophoretic effects were not observed. Cell rotation was observed in the frequency range from 1 kHz to 10 kHz. These results may be of use in cell separation and electrofusion in scientific research and technology.
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    Electrophoresis 7 (1986), S. 342-344 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Proteins with molecular weight between 66 000 and 950 000 were subjected to electrophoresis in 3 to 30 % linear gradients of polyacrylamide with volt-hour products between 2000 and 20 000. From the experimental data it was concluded that displacement of proteins decreased proportionally to the logarithm of time of electrophoresis. With these coordinates the fitness of the curves was found to be excellent (correlation coefficients were better than 0.993 for the analyzed proteins). These results support the hypothesis that there is no limit to be reached by a protein during its migration in a linear gradient of polyacrylamide. In addition we observed that the rate of decrease in mobility was proportional to the size of the protein.
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  • 87
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    Electrophoresis 7 (1986), S. 345-345 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
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  • 88
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    Electrophoresis 7 (1986), S. 392-393 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Rectangular sections of leaves, vacuum-infiltrated with distilled water or aqueous solutions of potassium chloride, were applied directly onto the surface of polyacrylamide gels followed by isoelectric focusing. Soluble peroxidases (free and ionically bound) were released from the tissue on isoelectric focusing with resultant characteristic zymograms for the different plant tissues.
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  • 89
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    Electrophoresis 7 (1986), S. 413-416 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Purified human blood clotting factor IX, although homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, showed two peaks when analyzed by crossed immunoelectrophoresis in the presence of calcium. Differential affinity of lectin from wheat germ (WGA) for the two forms of factor IX, detected by crossed affino-immunoelectrophoresis, demonstrated that carbohydrate moieties are involved in factor IX heterogeneities. The slow migrating peak has a higher affinity for WGA (Kd= 5.26 × 10-7 M) than the fast migrating peak (Kd= 1.29 × 10-5 M). This study emphasizes the usefulness of lectins as tools to assess homogeneity and integrity of glycoproteins.
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  • 90
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We have improved the Perrie and Perry method (Biochem. J. 1970, 119, 31-38) of urea-electrophoresis by the addition of a stacking gel containing 8.5 M urea and increased buffer capacity of the glycerol-containing separation gel. The system has been successfully applied to the analysis of myosin phosphorylation levels not only in myosin and actomyosin, but also in whole muscle samples dissolved in urea. By subjecting the samples to a simple centrifugation and filtration step, all myosin light chains including the unphosphorylated and phosphorylated species as well as calmodulin and troponin could be identified. With a sensitivity of about 5 pmols the procedure described eliminates the need for the time-consuming two-dimensional electrophoresis which is commonly used to determine phosphorylation levels in muscle samples.
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  • 91
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Urine analysis by two-dimensional gel electrophoresis with isoelectric focusing in immobilized pH gradients in the first dimension allows the loading of high sample volumes and/or of large amounts of salts. When applied to urinary protein analysis, it makes it possible to apply up to 1 mL of dialyzed, unconcentrated sample or up to 350 μL of unprocessed urine.
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  • 92
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    Electrophoresis 7 (1986), S. 441-443 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A simple method for obtaining permanent imprints of Coomassie Blue and Amido Black stained electrophoretograms on developed unexposed photographic paper and film is described. Copies of slab and two-dimensional electrophoretograms and crossed immunoelectrophoretograms were obtained by this technique. The method is fast, simple, inexpensive and can be adapted to make as many as five copies by repeated staining of the electrophoretogram. The copies are the exact size of the original gels and can be stored for a long time. The possible use of these imprints for the comparative study of immunoblots with the corresponding protein-stained gels is discussed.
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  • 93
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The binding sites of bovine serum albumin for rifamycin AF/013 were examined by means of analytical capillary isotachophoresis. At pH 7.5-7.9, there was only one binding site on non-defatted bovine serum albumin, while under the same conditions up to 20 binding sites could be detected on fatty acid-free albumin. In both cases the interaction became nonspecific above pH 8.0, resulting in a large number of rifamycin AF/013 molecules bound to albumin. Co-binding with oleic acid in vitro resulted in competition with all but the first high-affinity binding site for rifamycin AF/013, corroborating the findings made with non-defatted albumin. Considering albumin as a model, the results might explain the conflicting reports about the number of binding sites of DNA-dependent RNA polymerases for rifamy cin AF/013. Within a sharp pH-limit the highly specific binding becomes a nonspecific one. Moreover, the results suggest that the carrier function of bovine serum albumin might drastically change in vivo, depending on the pH of physiological fluids.
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  • 94
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    Electrophoresis 7 (1986), S. 426-428 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Murine Cu, Zn-superoxide dismutase (SOD) from erythrocytes has three isozymes, SOD-1A (pI 6.4), B (pI 5.7) and C (pI 5.0). It has been suggested that SOD-1A is formed epigenetically by asymmetric modification of SOD-1B where as SOD-1C is produced by treatment of superoxide dismutase with hydrogen peroxide. On two-dimensional gel electrophoretic analysis, each isozyme shows two forms, easily permuted into each other, and hence supposed to be in equilibrium. The zymogram patterns of murine liver, kidney, heart and brain are the same as those in erythrocytes although SOD activity levels are different in these tissues.
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  • 95
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    Electrophoresis 7 (1986), S. 430-432 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Simple detection cells for on-line UV absorbance and conductivity detection in capillary zone electrophoresis are described. The UV detection system employs a commercial photometer and optical fibers which are in direct contact with the outer walls of the separation capillary and conduct the light beam perpendicularly across the migrating zones. The conductivity detection cell consists of platinum wires protruding the wall of the separation capillary and thus in direct contact with the electrolytes inside. The electronic system is adopted from a commercially available conductivity detector for isotachophoresis.
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  • 96
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    Weinheim : Wiley-Blackwell
    Electrophoresis 7 (1986) 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
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  • 97
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    Electrophoresis 7 (1986), S. 433-435 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An electrolyte system involving 2-pyridinecarboxylate (Pic) buffer as the leading and formic acid as the terminating electrolyte was suggested for cationic capillary isotachophoresis of bases with low mobilities. Parameters of the system were studied for concentrations of the leading K+ ion of 1-30 mmol/L and for the Hpic/Kpic ratios of 3:1, 1:1 and 1:3 in the buffer. The effective mobility of the terminating H+ ion ranged between 3 and 30 X 10-9 m2V-1s-1 depending on the composition of the electrolyte system. The applicability of the system (at optimum concentration of K+ 5 mmol/L and the HPic/Kpic ratio 1:1) to the analysis of bases was characterized by a zone existence diagram and demonstrated by the separation of a model mixture containing tetramethylammonium, tetraethylammonium, tris(hydroxymethyl)aminomethane, ephedrine, codeine, nortriptyline, 1,10-phenanthroline, aminophenazone and 4-aminoantipyrine.
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  • 98
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    Weinheim : Wiley-Blackwell
    Electrophoresis 7 (1986), S. 487-491 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Computer simulation is used to analyze a system of two electrophoretic columns coupled by mixing the anolyte of one with the catholyte of the other. A mathematical model is presented which is used to predict the pH gradients formed by monovalent buffers in this system, when the currents in the columns are unequal. In the column with the higher current a pH gradient is created which increases from anode to cathode and is potentially useful for isoelectric focusing. The breadth of this gradient is dependent upon the ratio of the currents. The function of the second column is the compensation of buffer migration which occurs in the first column, thereby maintaining constant electrolyte composition. The effects of buffer pKs and mobilities are evaluated.
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  • 99
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Ultrathin-layer sodium dodecyl sulfate-polyacrylamide gradient gel electrophoresis in combination with silver staining is a highly sensitive and rapid method for molecular size analysis of urinary proteins. First results are achieved after 4 h (electrophoretic run, 100 min, followed by Coomassie Brilliant Blue staining, 2 h). After additional silver staining, including a recycling step, the results are ready for evaluation within 7 h. Urine samples do not need to be concentrated. Within a single gel, 25-27 samples can be run side by side under identical conditions and thus compared without ambiguity. By coelectrophoresis of pure proteins and immunological analysis 13 urinary proteins could be identified and for 7 of them the detection limits were determined. Glomerular protein patterns in samples of urine with a protein concentration in the normal range are compared with the concentration of albumin and transferrin measured by a sensitive enzyme immunoassay. Typical renal and extrarenal protein patterns are shown.
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  • 100
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    Weinheim : Wiley-Blackwell
    Electrophoresis 7 (1986) 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
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