bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct nuclear Overhauser effect refinement of crambin from two‐dimensional nmr data using a slow‐cooling annealing protocol
Authors: Bonvin Alexandre M. J. J. , Boelens Rolf , Kaptein Robert 
Published: May 2005

AbstractThe solution structure of crambin has been refined using a direct nuclear Overhauser effect (NOE) simulation approach (DINOSAUR) following a slow‐cooling simulated annealing protocol starting from eight previously obtained nmr and the x‐ray structures of crambin. Theoretical NOE intensities calculated with inclusion of local motions were directly compared to the experimental nmr data and forces were derived using a simple first‐order approximation for the calculation of the NOE gradient. A dynamic assignment procedure was applied for the peaks involving unassigned diastereotopic proton pairs or equivalent aromatic protons. With this approach, R factors could be minimized in a reasonable simulation time to low values (around 0.26) while deviations from ideal bond lengths and angles are still acceptable. The improvement in R factors is accompanied by an improvement of the precision of the structures, the rms deviations (rmsd; from the average) calculated on the ensemble of nine structures decreasing from 0.65 to 0.55 Å for backbone atoms and from 1.0 to 0.85 Å for all heavy atoms. The solution structure is significantly different from the x‐ray structure with rmsd for all atoms of 1.35 Å compared to 0.85 Å between solution structures. The largest differences are found for residues Thr‐21 and Pro‐22 in the loop region between the two α‐helices and for the side chain of Tyr‐29. © 1994 John Wiley & Sons, Inc.
Change in mobility of side chains due to neutralization of charged poly(L‐lysine) with dansyl group
Authors: Torii Toshinori , Yamashita Takashi , Horie Kazuyuki 
Published: May 2005

AbstractPoly(L‐lysine) having dansyl (5‐dimethylamino‐1‐naphthalene‐sulfonyl) groups to its side chains was prepared. The fluorescence spectra and fluorescence anisotropy ratios of the dansyl (DNS) group were measured in various conditions. In aqueous solution the increase in emission intensity was observed reflecting the alkali‐induced coil‐to‐helix transition. In aqueous‐methanolic solutions with methanol content above 60 wt %, the poly(L‐lysine) with DNS group (DNS‐PLL) was probed to show α‐helical conformation from CD spectra. With addition of alkali, the increase in fluorescence intensity of α‐helical DNS‐PLL and the drastic change in fluorescence anisotropy ratio were observed. In this case the rotational mobility of DNS probe decreases, gives a minimum at a certain concentration of added alkali, and then increases again up to approximately the initial level. At the concentration where the rotational mobility gives the minimum, intensity of scattered light gives a maximum. This shows that suppression of the mobility of DNS side chains is caused by the intermolecular aggregation of α‐helical DNS‐PLL. This concentration of added alkali corresponds to the midpoint of neutralization to charged side chains of the DNS‐PLL. The interaction that causes aggregate of α‐helical DNS‐PLL is suggested to be the intermolecular hydrogen bonding between neutralized and unneutralized side chains. © 1994 John Wiley & Sons, Inc.
Configurational statistics of the DNA duplex: Extended generator matrices to treat the rotations and translations of adjacent residues
Authors: Marky Nancy L. , Olson Wilma K. 
Published: May 2005

AbstractThe base‐to‐base virtual bond treatment of nucleic acids used in statistical mechanical calculations of polynucleotide chain properties has been refined by incorporating the six parameters that relate the positions and orientations of sequential rigid bodies. The scheme allows for the sequence‐dependent bending, twisting, and displacement of base pairs as well as for asymmetry in the angular and translational fluctuations of individual residues. Expressions are developed for the generator matrices required for the computation, as a function of chain length, of various parameters measuring the overall mean extension and shape of the DNA. Quantities of interest include the end‐to‐end vector r, the square of the end‐to‐end distance r2, the square radius of gyration s2, the center‐of‐gravity vector g, the second moments of inertia S×2, and the higher moments of r and g. The matrix expressions introduced in the 1960s by Flory and co‐workers for the determination of configuration‐dependent polymer chain averages are decomposed into their translational and orientational contributions so that the methods can be extended to the rigid body analysis of chemical moieties. The new expressions permit, for the first time, examination of the effects of sequence‐dependent translations, such as the lateral sliding of residues in A‐ and B‐helices and the vertical opening of base pairs in drug–DNA complexes, on the average extension and shape of the long flexible double helix. The approach is illustrated in the following paper using conformational energy estimates of the base sequence‐dependent flexibility of successive B‐DNA base pairs. © 1994 John Wiley & Sons, Inc.
Production of cobamides by Butyribacterium rettgeri
Authors: Perlman D. , Semar Joan B. 
Published: May 2005

AbstractCobamide production by Butyribacterium rettgeri Barker and Haas (ATCC 10825) was studied on a laboratory scale. Yields of the order of 5 μg./ml. were obtained when this anaerobe was grown for 6 days at 37°C. in a medium containing glucose, cornsteep liquor, cobalt nitrate, calcium carbonate, and sufficient ammonium hydroxide to keep the pH between 6.0 and 7.2. All of the vitamin was found associated with the bacterial cells, and examination of extracts of these cells showed the presence of 5,6‐dimethylbenzimidazolylcobamide coenzyme in large quantities. Supplementation of the fermentation medium with a number of benzimidazoles resulted in formation of traces of “new” cobamides with these bases in the nucleotide protion of the cobamide. Supplementation with a number of purines did not result in incorporation of these moieties in the cobamide portion of the molecule.
Pilot plant batch production of Neurospora crassa
Authors: Ensign Stewart , Kaplan Sam , Bonner David M. 
Published: May 2005

AbstractA 50‐gal. growth chamber is described together with its air filter and humidifier. The unit was designed especially for the production of Neurospora crassa, and was found to be effective in producing bulk amounts of mycelia with a high specific activity of tryptophan synthetase.
Pilot‐plant process for the isolation of a microbial polysaccharide with a quaternary ammonium compound
Authors: Albrecht W. J. , Sohns V. E. , Rogovin S. P. 
Published: May 2005

AbstractMicrobial polysaccharides which have many potential industrial applications are receiving more and more attention. One of the economic obstacles to the commercialization of these polysaccharides has been the cost of isolating them from fermented broth. To reduce this cost a recycling process was developed. The polyanionic polysaccharide synthesized from glucose by the activity of the bacterium Xanthomonas campestris NRRL B‐1459 is precipitated from the fermented broth with a quaternary ammonium compound (QAC).QAC is removed from the precipitate with methanol leaving the water‐soluble polysaccharide. Evaporation of the methanol wash removed the methanol and substantially all the QAC was recovered in the concentrate. This was recycled for subsequent precipitations. Chemical assay and the viscosity of water solutions of the isolated polysaccharide indicate no adverse effects on it from recycled QAC. The cost to make this polysaccharide by the described procedure is estimated to be $1.14/lb. This cost estimate includes land, buildings, raw materials, equipment, labor and supervision, utilities, factory supplies, working capital, and plant overhead.
Evaluation of dead cell fractions in suspensions of Penicillium chrysogenum
Authors: Borzani Walter , Vairo Marina L. R. 
Published: May 2005

AbstractAn adsorption colorimetric method is proposed for the determination of the percentage of dead cells in suspensions of Penicillium chrysogenum, based on the observed fact that a linear relation exists between that percentage and the dye concentration at the equilibrium point.
Uniform inoculation of nutrient surfaces
Authors: Clark D. S. 
Published: May 2005

AbstractA method of inoculating nutrient surfaces uniformly with bacterial cells has been developed. The method is based on controlled exposure of samples in a humidified chamber to a spray produced from a bacterial suspension. Factors affecting uniformity of inoculation (ionic strength of suspension, force of spray, distance between spray nozzle and sample, and exposure time) were studied in detail. Under optimum condition using agar medium in Petri plates, differences between total counts for six plates inoculated simultaneously, or between counts for individual 2 cm.2 areas taken at any location on any of the plates, were not statistically significant at the 5% level. The coefficient of variability for counts on 2 cm.2 areas renged from 8 to 12% between tests of 216 counts each.
Disposable shaker flasks
Authors: Falch E. A. , Hedén C.‐G. 
Published: May 2005

AbstractA disposable plastic tetrahedron bag is described which is suitable for holding a 50 ml. culture on a shaker table. Bags can be made out of polypropylene or Teflon and they are quite simple and inexpensive. The tetrahedrons make excellent use of the shaker table space and they give a threefold increase in aeration efficiency over Erlenmeyer flasks.
The development of a process for recovering nucleotides from Bakers' yeast
Authors: Munden J. E. , Crook E. M. , Donald M. B. 
Published: May 2005

AbstractA process has been developed giving over‐all yields of about 50%: which could be increased to about 80% with higher material costs and processing time. The preferred method of recovering nucleotides from the cytoplasm has been thermal extraction by means of a heat exchanger followed by filtration, protein precipitation, and carbon adsorption. The concentrated eluate from the carbon is absorbed onto Dowex 1 ion‐exchange resin, and groups of nucleotides are removed by pH‐defined eluents and recovered by a second carbon adsorption. Finally, standard ion‐exchange resolutions have been used to recover individual nucleotides. Other biochemicals in the extract have been investigated, and preliminary work has been done on the combination of nucleotide extraction with the recovery of nucleic acids from the residual cells.
Some systems for the biological oxidation of phenol‐bearing waste waters
Authors: Smith R. M. 
Published: May 2005

AbstractPhenol‐bearing waste waters continue to be an area of wide concern for various industries faced with the task of cleaning up effluents containing relatively small amounts of these materials. The microbiological aspects of the degradation of these materials in pure culture and waste treatment plants is reviewed. Actual operating experiences at three plants of The Dow Chemical Company, where phenols are present in combination with other widely varying waste constituents, are discussed.
Estimating biodegradability and treatability of organic water pollutants
Authors: Ludzack F. J. , Ettinger M. B. 
Published: May 2005

AbstractBiological purification of water pollutants depends upon a complex balance of organisms and environment conducive to effective metabolism. The bench scale test is useful to determine effects of a given waste water on that balance and to suggest controls promoting optimum purification. Applicability of laboratory results depends, in part, upon an experimental design similating anticipated operating conditions. This paper discusses advantages and limitations of historical bench‐tests as a guide for design of tests giving data that are more useful during full‐scale operation.
An apparatus for continuous electrophoresis on a preparative scale
Authors: Blakebrough N. , Brookes R. 
Published: May 2005

AbstractA method of performing electrophoretic separations in a thin horizontal layer of continuously flowing buffer has been developed. The theoretical considerations that make possible the use of a thin layer for stabilization against convection effects, without the assistance of a packing material, are discussed. The apparatus is described together with an example of its performance, and a comparison with that of other workers.
Continuous cultivation of Escherichia coli possessing high penicillin–acylase activity
Authors: Sikyta Bohumil , Slezák Josef 
Published: May 2005

AbstractThe authors describe continuous cultivations of Escherichia coli possessing high penicillin‐acylase activity in corn‐steep liquor, peptone, and ammonium phenylacetate containing nutrient medium. If the cultivation is performed in the absence of ammonium phenylacetate the enzymic activities of cells from the batch as well as the continuous cultures are very low. The enzymic activity of cells in the batch process was considerably increased by the addition of 0.015% ammonium phenylacetate to the nutrient medium. Further increase of ammonium phenylacetate concentration did not result in any further increase of acylase activity. Continuous cultivation of the bacteria at the above ammonium phenyl‐acetate concentration was unsuccessful, as the enzymic activity of the bacteria constantly decreased during the process. On increasing the concentration of ammonium phenylacetate in the medium to 0.15% the authors succeeded in maintaining the enzymic activity of the bacteria at the same level as in the batch process performed at 0.015% concentration, throughout the whole continuous cultivation. At the dilution rate D = 0.5 hr.−1 the concentration of cells in the culture effluent from the fermentor at the steady state was equal to cell concentration at the end of batch cultivation. In relation to the cultivation time the output of cells in continuous cultivation is almost seven times higher as compared with the batch process.
Investigations of conditions for production of penicillin and chlortetracycline in submerged fermentation
Authors: Matelová V. 
Published: May 2005

AbstractDuring investigations of submerged fermentation of penicillin and chlortetracycline, we reached the conclusion that production in relation to oxygen transfer is relatively uninfluenced by the composition of the fermentation medium. The maximum penicillin production, using the strain Penicillium chrysogenum NG in flasks on a shaker was uniformly achieved in all investigated media with an oxygen transfer rate of 0.81; and in chlortetracycline, using strain Streptomyces aureofaciens BMK−11, with an oxygen transfer rate of 0.59 ml. O2/ml./hour. The primary factor which influences the antibiotics production is the transfer of oxygen into the liquid. The absolute volume of production is, however, partly influenced by mechanical conditions of fermentation and the composition of the medium.
Measurement of the kinetics of biological systems at elevated temperatures utilizing flow techniques
Authors: Wang Daniel I‐C. , Humphrey Arthur E. , Eagleton Lee C. 
Published: May 2005

AbstractContinuous flow‐type reactors have been used to study the kinetics of biological systems for quite some time. For continuous media sterilization, tubular flow reactors are particularly useful being simple in character and easy to control. However, one aspect quite often neglected in sterilization calculations is the residence time distribution of the reactor system. Serious errors in estimating the degree of bacterial destruction can be encountered if the residence time distribution is neglected; especially when a high degree of destruction is desired. This paper reports a study made to characterize and use the residence time distribution of a tubular reactor in the interpretation of high‐temperature, short exposure time data for inactivation of Bacillus stearothermophilus spores. Mathematical models accounting for the residence time distribution of the tubular reactor have been proposed and employed to obtain high‐temperature death‐rate data.
Composting conversion of solid wastes for mushroom growing
Authors: Block S. S. 
Published: May 2005

AbstractMethods for composting small quantities of organic materials have been developed in order to be able to better study the composting process. A composting bin was developed which holds 27 cu. ft. of compost and which provides uniform conditions of temperature, moisture, and aeration within the compost mass. A system for indoor composting of less than one cubic foot of material has been developed and is described. The methods have been shown to be reliable and reproducible. The composts were evaluated for their suitability for mushroom growing and were found to give high yields of mushrooms.
Steam sterilizable probes for dissolved oxygen measurement
Authors: Johnson Marvin J. , Borkowski John , Engblom Curt 
Published: May 2005

AbstractSteam‐sterilizable membrane probes for monitoring the dissolved oxygen level in fermentors, or the oxygen content of gas streams, are described. The probes have a silver cathode, a lead anode, and an acetate buffer as an electrolyte. The membrane is Teflon. The current output of the probes in the absence of oxygen is negligible.
An automatic aeration control system for biosynthetic processes
Authors: Lengyel Z. L. , Nyiri L. 
Published: May 2005

AbstractAn automatic aeration controller was constructed to assure the optimal amount of oxygen for aerobic biosynthetic processes. A platinum electrode and a KCl bridge for the calomel electrode were inserted hermetically into the fermentor and were sterilized with the culture medium. The electrode potential developed at the surface of the Pt electrode continuously indicated the actual oxygen concentration of the medium. This served as the controlled variable of the system. The concentration of dissolved oxygen resulted from the actual demand and supply of the microorganism. The electrode potential, which was the measured variable of the process, operated a closed‐loop automatic aeration system. The controller activated an air inlet valve in order to balance the controlled variable. The automatic controller operated in fermentors of industrial scale for long periods in a satisfactory manner.
Resistance of microorganisms to hydrostatic pressure
Authors: Timson W. J. , Short A. J. 
Published: May 2005

AbstractA small fraction, about 0.05%, of the microorganisms in milk are resistant to pressure to at least 150,000 p.s.i. The pressure‐resistant microorganisms were shown to be mainly bacterial spores. Some of the pressure‐resistant organisms were identified. The lethal effect of pressure is more pronounced in the solid phase than in the liquid phase of water. B. subtilis was found to be capable of surviving solid‐phase transitions from Ice II, III, and V to Ice I. The lethal effect of high pressure in the liquid phase of water was found not to be counteracted by an increase in temperature. The pressure resistance of B. subtilis was found to be maximum around neutral or slightly basic pH. The damaging effect of low and high pH are counteracted by sodium chloride and glucose. It is suggested that the primary mechanism of protein denaturation by pressures above 30,000 p.s.i. is ionization and formation of ionic bonds between charged groups on proteins, altering their solubility.
Isolation of bacterial polysaccharide B‐1459 through calcium hydroxide complex formation
Authors: Mehltretter C. L. 
Published: May 2005

AbstractA method is described for the isolation of bacterial polysaccharide B‐1459 from aqueous dispersion as a calcium hydroxide complex. The polysaccharide is liberated in fibrous form from the complex by means of hydrochloric acid in methanol solution. Overall recovery of the polysaccharide from aqueous dispersion is 85%. Direct conversion of the insoluble calcium hydroxide complex to aqueous polysaccharide solution appears to be a low‐cost procedure for preparing viscous solutions for industrial use.
Studies on methanol oxidizing bacteria
Authors: Häggström Lena 
Published: May 2005

AbstractA mixed culture of methanol oxidizing bacteria has been cultivated on simple inorganic salts medium supplemented with methanol. Optimal growth occurred at 31°C, pH 6.0–6.3, and a methanol concentration between 1 and 2 ml/1, of medium. The maximum yield was 4.5 g dw/I and the mean generation time 3.2 hr.It was estimated that 41% of methanol carbon was converted into cell‐carbon, and that 73% of the inorganic nitrogen was converted to organic nitrogen.
Large scale production of transfer ribonucleic acids fromE. coliK‐12 MO7
Authors: Hancher C. W. , Phares E. F. , Novelli G. David , Kelmers A. D. 
Published: May 2005

AbstractAn engineering‐scale procedure for the recovery of 300–400 g batches of mixed transfer ribonucleic acids is described. Semicontinuous growth ofE. coliK‐12 MO7 yielded 77 kg of harvested cells in four days. Phenol extraction and ethanol precipitation recovered a crude tRNA material that was further purified by DKAE‐cellulose chromatography in runs of 1 × 106A260units each on a 6 × 30 in. column using a 240 1, gradient elution. The purified tRNAs were partially concentrated and resolved into three groups.
Physiology of, an enzyme production by, plant cell cultures
Authors: Veliky I. , Sandkvist A. , Martin S. M. 
Published: May 2005

AbstractRed kidney bean (Phascolus vulgaris) cells, derived from roof, callus, were grown in suspension culture in shake flasks and in laboratory fermentors using batch and continuous batch culture techniques. The medium contained casein hydrolysate, sucrose, inorganic salts, vitamins, and growth hormones. In continuous batch culture yields of up to 171 g wet weight, (8.5 g dry weight) per liter were obtained in 7 days. Organic nitrogen was used preferentially. Growth on nitrate was considerably slower than on organic nitrogen sources. Indole acetic and naphthalene acetic acids were not essential for good growth of the cells whereas kinetin and 2, 4‐D were. The optimum pH for growth was about p11 4.5. The presence of amylase and peroxidase was detected in culture filtrates. Amylase activity was low in either the presence or the absence of starch in the medium. Peroxidase production could be related directly with growth of the culture. Maximum peroxidase yield, as measured by the guaiacol method and expressed as horse radish peroxidase, was 1.25 × 10−8 M.
Continuous enzyme processing: The isolation of prolyl‐tRNA synthetase from Phaseolus Aureus
Authors: Dunnill P. , Currie J. A. , Lilly M. D. 
Published: May 2005

AbstractA pilot‐plant process has been developed for the continuous extraction and partial purification of prolyl‐tRNA synthetase from mung bean. The bean slurry was wet ground in a hammer mill, clarified by two‐stage centrifugation, and the protein in the effluent fractionated by precipitation at pH values of 5.2 and 4.2. The throughput was 13 kg dry bean/hr. The improved extraction process and reduced processing time resulted in an enzyme product with a specific activity 16 × that previously obtained in the batch process. The yield was also 50–60 times higher.
Starch conversion by immobilized glucoamylase
Authors: Bachler M. J. , Strandberg G. W. , Smiley K. L. 
Published: May 2005

AbstractGlucoamylase bound to DEAE‐cellulose in 0.05 M sodium acetate, pH 4.0, is active in the conversion of starch to glucose. The activity of the DEAE‐cellulose‐bound enzyme ranges from 16 to 55% of the activity of the free enzyme. Binding of the enzyme narrows the pH optimum to approximately 4.0 and lowers the temperature optimum to 40–50°C as compared to a 60°C temperature optimum for the free enzyme. Concentrations of acetate buffer above 0.1 M disrupt the DEAE‐cellulose‐enzyme complex. Columns were used with some success for the continuous conversion of starch. Pretreatment of the starch with α‐amylase and clarification were necessary to prevent blocking of the column. Columns maintained activity for more than 3 weeks of continuous operation.