bluuebunny/crossref_metadata_2025_split huggingface dataset:
Small‐angle x‐ray scattering of κ‐carrageenan based systems: Sols, gels, and blends with carob galactomannan
Authors: Turquois Tristan , Rochas Cyrille , Taravel Francois‐R , Doublier Jean Louis , Axelos Monique‐A‐V. 
Published: December 2004

AbstractSmall‐angle x‐ray scattering using a synchroton x‐ray monochromatic radiation was carried out to investigate the structure of different polysaccharides in aqueous medium: carob galactomannan, κ‐carrageenan in the sol and in the gel states, and κ‐carrageenan‐carob galactomannan mixed systems. Experiments performed on a 0.2% carob galactomannan solutions confirmed that this polysaccharide behaved as a neutral polymer in a good solvent. For K‐carrageenan in the / state, either in the sodium form or in the cesium form, a maximum in the scattering curve was evidenced. Position and height of this maximum changed with K‐carrageenan concentration in close agreement with what is expected for wormlike polyelectrolyte in semidilute solution. In the case of k‐carrageenan in the gel state, in the cesium form, scattering curves also exhibited a maximum at an intermediate Q value. The position of this correlation peak did not change with concentration while its intensity increased. This effect was ascribed to a packing of rodlike structures by analogy with a suspension of colloidal elongated particles. This local structure could be viewed as bundles of parallel double helices. Addition of carobgalactomannan in κ‐carrageenan gels induced dramatic structural changes. As the galactomannan concentration increased, the correlation peak tended to vanish. In contrast, no change in the cross‐sectional radius of gyration was noticed. This phenomenon suggested a screening effect of the galactomannan, resulting in a loss of the correlation between the κ‐carrageenan double helices. © 1995 John Wiley & Sons, Inc.
Slow conformational exchange in DNA minihairpin loops: A conformationalstudy of the circular dumbbell d〈pCGC‐TT‐GCG‐TT〉
Authors: Ippel Johannes H , Lanzotti Virginia , Galeone Aldo , Mayol Luciano , van den Boogaart Jaquelien E , Pikkemaat Jeroen A , Altona Cornelis 
Published: December 2004

AbstractIn recent years various examples of highly stable two‐residue hairpin loops (miniloops) in DNA have been encountered. As the detailed structure and stability of miniloops appear to be determined not only by the nature and sequence of the two bases in the loop, but also by the closing base pair, it is desirable to carry out in‐depth studies of especially designed small model DNA compounds. Therefore, a circular DNA dumbbell‐like molecule is tailored to consist of a stem of three Watson–Crick base pairs, flanked on each side by a minihairpin loop. The resulting circular DNA decanter 5′‐d〈pCGC‐ TT‐GCG‐ TT〉 ‐3′ (I) is studied in solution by means of nmr spectroscope. At a temperature of 269 K the molecule occurs in a 50/50 mixture of two dumbbell structures (denoted L2L2 and L2L4). L2L2 contains three Watson–Crick C‐G base pairs and two two‐residue loops (H2‐family type) in opposite parts of the molecule. On raising the temperature from 269 to 314 K. The L2L4 conformer becomes increasingly dominant (95% at 314 K). This conformer has a partially disrupted closing G‐C base pair in the 5′‐GTTC‐3′ loop with only one remaining solvent‐accessible hydrogen bond between NHα of the cytosine C(1) and O6 of the guanine G(8), whereas the opposite 5′‐CTTG‐3′ loop remains stable.The disruption of the C(1)‐G(8) base pair in the L2L4 form is correlated with the presence of a syn orientation for the C(1) base at the 5′‐3′ loop‐stem junction in the 5′‐GTTC‐3′ loop. The two conformers. L2L2 and L2L4, occur in slow equilibrium (2–20 s−1). Moderate line broadening of specific 1H, 13C, and 31P resonances of residues C(1), G(8), T(9), and T(10) at low temperatures, due to chemical exchange between L2L2 and L2L4, show that the interconversion from an anti to syn conformer in residue C(1) has a small local effect on the structure of the dumbbell. T1 relaxation measurements, chemical‐shift considerations, and complete hand‐shape calculations of the exchange process of the G(8) imino proton reveal a possibility for the existence of multiconformational slates in the anti–syn equilibrium. © 1995 John Wiley & Sons, Inc.
1H‐nmr studies on the structure of a new thionin from barley endosperm
Authors: Bruix M , González C , Santoro J , Soriano F , Rocher A , Méndez E , Rico M 
Published: December 2004

AbstractA new thionin from barley, ω‐hordothionin, has been shown to exist in aqueous solution as a mixture of two different isoforms in a 3:2 ratio, as revealed by a complete analysis of its two‐dimensional 1H‐nmr spectra. The conformational heterogeneity arises frtm cis–trans isomerism ahout the Phe 12–Pro 13 peptide bond, where the major, form corresponds to the cis conformation. The complete assignment of chemical shifts and nuclear Overhaiiser effects (NOES) of the two isoforms allow a detailed comparative analysis of their conformational properties, even though a complete calculation of their solution structures is not possible because of a somewhat limited number of NOE constraints. Structures for the two isomers could be modeled, however, on the basis of the high structural homology between ω‐hordothionin and related γ‐thionins, and under the conditions of satisfying all observed experimental data. The two isoforms adopt practically identical global folds and the structural changes imposed by cis–trans isomerization are confined to the region proximal to Pro 13. The cis–trans isomerism occurs in a conserved loop connecting the first β‐strand of the triple‐stranded antiparallel β‐sheet and the α‐helix. A comparative analysis of the sequences of this loop in the different thionins suggests that the cis–trans equilibrium about the X‐Pro peptide bond depends on the size of the side chain of X (X = Gly in γ‐thionins and Phe in ω‐thionin). The structural homology of this new thionin with γ‐thionins as well as with some scorpion toxins and insect defensins suggests that these proteins may share a common mode of functional activity. © 1995 John Wiley & Sons, Inc.
Rational design, synthesis, and biological evaluation of novel growth hormone releasing factor analogues
Authors: Campbell Robert M. , Bongers Jacob , Felix Arthur M. 
Published: December 2004

AbstractSince its initial discovery in 1982, growth hormone‐releasing factor (GRF) has been the subject of intense investigation. This interest was prompted by the potential application of GRF for Stimulating growth in dwarf humans and for performance enhancement in livestock. Substantial research has been focused upon the development of potent, long‐acting analogs as therapeutics. Herein is described a summary of the cumulative efforts of various laboratories endeavoring in this quest. The rationale utilized in GRF analog development is discussed: (1) determination of bioactive core. (2) evaluation of secondary structure, and (3) elucidation of degradation pathways (chemical and enzymatic). Using this information, several series of linear (unnatural and natural sequence) and cyclic GRF analogs were designed, synthesized, and evaluated. Stimulated by the constraints of commercial production, innovative, alternative methods of synthesis were explored: solid‐phase, solution‐phase, enzymatic, and recombinant. To date, the most promising candidate for drug development is [His1, Val2, Gln8, Ala15, Leu27]‐hGRF(1‐32)‐OH. This natural sequence analog, consisting of rodent and human sequences, incorporates the bioactive core, preferred secondary structure, resistance to chemical and enzymatic degradation: with the added benefit of amenability to large‐scale recombinant synthesis. © 1994 John Wiley & Sons, Inc.
Bradykinin antagonists: Development and applications
Authors: Stewart John M. 
Published: December 2004

AbstractBradykinin (BK) is involved in regulation of every major physiological system and is an initiator or mediator of many pathophysiological conditions. Rapid progress in understanding these aspects of BK biology has come since the discovery of BK antagonists. This article reviews principal points in the history of the kallikrein–kinin field and of kinin biology. The chemistry and development of antagonists for B1 and B2 kinin receptors is discussed. Uses of the antagonists in biomedical research and potential clinical applications are presented. © 1994 John Wiley & Sons, Inc.
A review of the utility of soluble peptide combinatorial libraries
Authors: Pinilla Clemencia , Appel Jon , Blondelle Sylvie , Dooley Colette , Dörner Barbara , Eichler Jutta , Ostresh John , Houghten Richard A. 
Published: December 2004

AbstractThis is paper reviews the preparation and use of soluble synthetic combinatorial libraries (SCLs) made up of millions of peptide and nonpeptide sequences for the identification of highly active individual compounds. First presented in 1991. SCLs have been prepared in a number of different lengths and formats, and are composed entirely of L‐, D‐, and unnatural amino acids. Also, existing peptide libraries have been chemically transformed to yield large diversities of nonpeptidic compounds. This review encompasses the published work from this laboratory using SCLs for the identification of antigenic sequences recognized by monoclonal antibodies, novel peptide agonists and antagonists to opioid receptors, new trypsin inhibitors, novel antibacterials, and compounds that inhibit melittin's hemolytic activity. SCLs offer a fundamental, practical advance in the study of interactions between peptide and nonpeptide sequences and their biochemical or pharmacological targets. © 1994 John Wiley & Sons, Inc.
Vibrational optical activity of oligopeptides
Authors: Freedman Teresa B. , Nafie Laurence A. , Keiderling Timothy A. 
Published: December 2004

AbstractVibrational optical activity (VOA) is a relatively newspectroscopic technique, which has two principal manifestations, ir vibrational CD and vibrational Raman optical activity. Progress in the study of oligopeptides using both of these forms of VOA is reviewed from the perspective of theoretical and instrumental techniques, spectral results, and structural interpretations. © 1994 John Wiley & Sons, Inc.
The importance of extended conformations and, in particular, the PII conformation for the molecular recognition of peptides
Authors: Siligardi Giuliano , Drake Alex F. 
Published: December 2004

AbstractCrystallographic, isotopic labeling nmr and transferred nuclear Overhauser effect studies have highlighted the extended conformation as a very important element of secondary structure at the binding site of many peptide/protein complexes including peptide inhibitors–enzymes, B‐cell epitopes–antibodies, and T‐cell epitopes–major histocompatibility complex (MHC) of class I and II complexes. This paper discusses the peptide ligand conformation consequences of these findings particularly in view of the identification of the PII conformation (left‐handed extended polyproline II) in free solution. © 1994 John Wiley & Sons, Inc.
Protein structural analysis as a tool for protein design
Authors: Leplae Raphael , Lahm Armin , Tramontane Anna 
Published: December 2004

AbstractThe analysis of known protein structures is a very valuable and indispensable tool for deciphering the complex rules relating sequence to structure in proteins. On the other hand, the design of novel proteins is certainly the most severe test of our understanding of such rules. In this report we describe our own attempt to develop appropriate tools for the investigation of known protein structure properties and their applications to the design of a novel, all β protein. The success of the design project is a demonstration of the usefulness of careful analysis of the data base of known protein structures. © 1994 John Wiley & Sons, Inc.
Production of cellulase and protein from barley straw by Trichoderma viride
Authors: Peitersen Nicolai 
Published: December 2004

AbstractThe cellulase production by two strains of the cellulolytic fungus Trichoderma viride was examined. The fungi were grown on different preparations of barley straw pretreated with NaOH under high pressure. The production of cellulases and microbial protein by the better strain (QM 9123) was investigated in an aerated 5‐liter fermenter under varying stirring rates (200‐350 rpm) and straw concentrations (1–2%). The pH was kept between 3.5 and 4.5. The growth of the fungus was followed by measuring the quantity of CO2 produced and the cell protein. After 2–6 days growth ceased, the lag phases lasting 0–2 days, increasing with increasing straw concentrations. The maximum enzyme yields were reached after 4–10 days. The protein content of the product was 21–26% and up to 70% of the straw was utilized. The yield constants were calculated to be 0.40–0.56; of the same order as those which can be obtained by growing the fungus on glucose.
Electromagnetic induced kinetic effects on charged substrates in localized enzyme systems
Authors: Seto Y. J. , Hsieh S. T. 
Published: December 2004

AbstractAn analytical expression for the rate efficiency factor of planar localized enzyme systems is derived. The derivation takes into account the isothermal kinetic effect under the externally imposed perturbation of combined electrostatic and high frequency time‐varying fields. The contribution of each individual field to the enzyme reaction is examined through the basic mechanism in which charged substrates interact, with the specific perturbing field. The interaction mechanisms for the electrostatic and for the time‐varying fields are found to be different. This difference regulates the different manners in which enzymatic reaction rates are altered. Enzymatic reactions under electrostatic perturbation can be retarded or enhanced depending on the field polarization. At sufficiently high field intensities the reaction rate may approach zero or approach a maximum value equal to the turnover number of the enzyme. Time‐varying field perturbations, on the other hand, always enhance the enzymatic reactions if bunching effects are negligible. At sufficiently high field intensities, the reaction may approach a value equal to that of the free enzyme system. Several typical numerical examples on pure electrostatic field perturbations, pure time‐varying field perturbations, and combined field perturbations are also presented.
Fed batch culture of Saccharomyces cerevisiae: A perspective of computer control to enhance the productivity in baker's yeast cultivation
Authors: Aiba Shuichi , Nagai Shiro , Nishizawa Yoshinori 
Published: December 2004

AbstractA means to avoid the glucose effect in the production of baker's yeast from glucose and/or molasses in a fed batch culture by controlling the feed rate of fresh medium with an ad hoc measurement of the respiratory quotient, RQ, is presented. The feed rate is changed stepwise here such that the value of RQ ranges from 1.0 to 1.2 throughout the cultivation. Thus far, the specific growth rate based on the total cell mass and the growth yield obtained throughout are 0.24 hr−1 and 0.55 g cell/g glucose.Prior to the experimental run mentioned above, equations to predetermine the feed rate and concentration of glucose in the feed are derived from the mass balance of limiting substrates (glucose). Since values of either RQ or I (Q x, oxygen consumption rate with respect to the total cell mass in the fermenter) can be measured quite easily and reliably, computer control of the fermentation in light of this information is discussed.
Microbial production of methane from municipal refuse
Authors: Pfeffer John T. , Khan Khalique A. 
Published: December 2004

AbstractA heat and caustic pretreatment process has been tested to determine the increase in gas yield that can be obtained from fermentation of organic municipal refuse. A treatment temperature of 130°C and a NaOH concentration of 3 g/100 g of dry solids resulted in the highest gas yield for the conditions tested. The probable increase in gas yield was 20% for the best conditions tested. The treatment procedure also substantially increased the rates of gas production. A high conversion efficiency is possible at much shorter reactor retention times with pretreatment than without pretreatment.
Theoretical model for a submerged biological filter
Authors: Jennings P. A. , Snoeyink V. L. , Chian E. S. K. 
Published: December 2004

AbstractA mathematical model was developed for percent removal of a pure, non‐adsorbable, biodegradable substrate in a submerged biological filter using the nonlinear Monod expression for the substrate utilization rate. Analytical solutions were obtained using zero and first order linearizations of the Monod expression and were compared to the numerical solution of the nonlinear system. The relevant dimensionless parameter groups describing the system were identified and their effects on substrate flux into the biolayer, effectiveness factor, and percent removal were also examined. Criteria were established for determining the relative accuracy of the two biokinetic approximations and for determining values of “limiting” biolayer thickness.There are two major results of engineering significance. (1) The approximation of the nonlinear Monod expression by a first order rate expression yields accurate results for a much wider range of bulk concentrations than might be expected from inspection of the Monod half‐velocity coefficient for a given substrate. (2) Percent removal of substrate is a weak function of biolayer thickness (and thus total cell mass) when the thickness is greater than a rather small limiting value but is a strong function of particle radius (and thus biolayer surface area) for a wide range of parameter values including those of common interest.
Utilization of cellulosic materials through enzymatic hydrolysis. I. Fermentation of hydrolysate to ethanol and single‐cell protein
Authors: Cysewski Gerald R. , Wilke Charles R. 
Published: December 2004

AbstractEthanol fermentation studies were conducted with Saccharomyces cerevisiae ATCC #4126, to determine the optimal conditions of oxygen tension and feed sugar concentration. In long‐term continuous culture maximum ethanol production was found to occur at 0.07 mmHg oxygen tension and 10% glucose feed concentration. Preliminary process design and cost studies are developed for industrial scale fermentations to produce ethanol and torula yeast from sugars obtained by enzymatic hydrolysis of newsprint.
The immobilization of microbial cells, subcellular organelles, and enzymes in calcium alginate gels
Authors: Kierstan M. , Bucke C. 
Published: December 2004

AbstractSaccharomyces cerevisiae cells, Kluyveromyces marxianus cells, inulase, glucose oxidase, chloroplasts, and mitochondria were immobilized in calcium alginate gels.Ethanol production from glucose solutions by an immobilized preparation of S. cerevisiae was demonstrated over a total of twenty‐three days, and the half‐life of such a preparation was shown to be about ten days.Immobilized K. marxianus, inulase, and glucose oxidase preparations were used to demonstrate the porosity and retraining properties of calcium alginate gels.Calcium alginate–immobilized chloroplasts were shown to perform the Hill reaction.Some experiments with immobilized mitochondria are reported.
Phenotypic modifications in amino acid profiles of cell residues ofcandida utilisandenterobacter aerogenes
Authors: Alroy Yair , Tannenbaum Steven R. 
Published: December 2004

AbstractGlucose‐limited chemostat cultures ofCandida utiliswere cultivated at various pH levels (3.0–7.5), temperatures (15–37.5°C), dilution rates (0.06–0.42 hr−1), and with one of two nitrogen sources (NHor NO).Enterobacter aerogeneswas also cultivated in the chemostat under nitrogen and phosphorus limitations. The amino acid profile of total cell protein is expressed as the content of each amino acid relative to the sum of all amino acids recovered after acid hydrolysis. Cell residues obtained after hot trichloroacetic acid extraction display small variations in amino acid profile. Some of these variations correlate with the growth rate at satisfactory levels of statistical significance. InC. utilis, the correlations cover increased levels of lysine, arginine, and leucine and decreased levels of serine and glutamic acid with increased “reduced dilution rate” (D/Dc). InE. aerogenes, increased levels of lysine and arginine and a decreased level of glutamic acid correlate with increased dilution rate. The directions of most of these correlations and the extents of those pertaining to lysine and arginine are consistent with the change predicted to occur simultaneously in the relative level of the ribosomal protein group.
Media suitable for industrial production of Entomophthora virulenta zygospores
Authors: Latgé J.‐P. , Soper R. S. , Madore C. D. 
Published: December 2004

AbstractEntomophthora virulenta has been grown using inexpensive, commercial grade nutrient sources in order to produce a resting spore formulation available to agriculture. Solid media and liquid media in shake flasks and fermentors were examined. The best carbon sources for sporulation were dextrose and corn syrup, while the best nitrogen sources were yeast extract, soybean, and cottonseed flours. The optimal nutrient concentration (12%) produced 3 × 106spores/ml with a 70% germination rate within five days.
Properties and biodegradation of a bioemulsifier from Corynebacterium hydrocarboclastus
Authors: Zajic J. E. , Guignard Hélène , Gerson D. F. 
Published: December 2004

AbstractAn extracellular polymer was produced by continuous fermentation of Corynebacterium hydrocarboclastus on kerosene in a 24 liter reactor. This polymer was composed of protein, lipid, and carbohydrates. The polymer possesed surface active properties, and had two critical micelle concentrations. Its effectiveness was quite comparable to the effectiveness of synthetic surface active agents such as Tween 80 and Span 20; however, its efficiency was much lower. The polymer also had emulsifying properties. Maximum emulsification was obtained at pH 6. The emulsifying properties were unaffected by high salt concentration [up to 5% (w/v) in Na+], and tolerated a water hardness up to 5,000 ppm. A 2 hr treatment of the polymer at temperatures higher than 65°C resulted in a loss of its emulsifying properties. Two microorganisms, named SLYS and Y, isolated from soil, were able to grow on the polymer as sole carbon and energy source, thus proving its biodegradability. SLYS was tentatively identified as Flavobacterium breve and Y as Flavobacterium devorans.
Differential speed two roll mill pretreatment of cellulosic materials for enzymatic hydrolysis
Authors: Tassinari Thomas , Macy Charles 
Published: December 2004

AbstractDifferential speed two roll milling is an effective pretreatment for increasing the susceptibility of cellulose to enzymatic hydrolysis. Using mills with three, six, and ten in. diam rolls and processing times of 10 min or less results in the following percent increases in susceptibility over untreated controls: cotton, 1100; maple chips, 1600; white pine chips, 600; newspaper, 125. In comparison, ball milling of newspaper for 24 hr gives only a 62% increase. A further advantage of the roll mill is the increased wet density of the product permitting higher slurry concentrations during hydrolysis. Important parameters of mill effectiveness are roll clearance and processing time.