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Precipitant
Selected AbstractsClean synthesis of propylene carbonate from urea and 1,2-propylene glycol over zinc,iron double oxide catalystJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2006Xinqiang Zhao Abstract A series of zinc,iron double oxide catalysts has been prepared. The suitable preparation conditions are as follows: zinc nitrate and iron nitrate as precursors, molar ratio of Zn/Fe 2:1, ammonia as the precipitant, precipitation end-point pH 8.04, and calcination temperature 450 °C. The clean synthesis of propylene carbonate (PC) via urea and 1,2-propylene glycol (PG) over the zinc,iron double oxide catalyst has been studied. The optimal reaction conditions are as follows: reaction temperature 170 °C, reaction time 2 h, catalyst concentration 1.4% (wt), and molar ratio of urea to PG 1:4. The highest yield of PC was 78.6%. XRD, CO2 -TPD and XPS techniques have been employed for catalyst characterization. Two kinds of crystal phase, ZnO and ZnFe2O4, have been detected and their synergistic effect promotes the catalytic activity of the oxide catalysts. Copyright © 2006 Society of Chemical Industry [source] Recovery of cadmium from a zinc hydrometallurgical leachate using reactive emulsion liquid membrane technologyJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2004Jianzhang Fang Abstract A new emulsion liquid membrane process using 3,5-diisopropylsalicylic acid (DIPSA) and triisobutylphosphine sulfide (TIBPS) as carriers, and ammonium sulfide (NH4)2S as precipitant is described. The reactive nature of sulfide ions with extracted cadmium ions in the internal aqueous phase significantly increases cadmium recovery and minimizes zinc impurities. The new process is applied to the enrichment of a low concentration of cadmium ions from a solution containing a high concentration of zinc ions. Under optimum operating conditions, a single stage process produced a cadmium recovery of 98% at a cadmium sulfide content of 99.6%. The results are encouraging for potential applications in zinc hydrometallurgy for recovery of cadmium from sulfuric acid leaching solution of zinc ores. Copyright © 2004 Society of Chemical Industry [source] Dynamics of isoelectric precipitation of casein using sulfuric acidAICHE JOURNAL, Issue 8 2003G. W. Hofland The acid precipitation of casein from skim milk is an interesting and complex operation, as it involves several mechanistic steps occurring simultaneously. Research has focused so far on the influence of static variables such as temperature and final pH on the curd properties. Here the dynamics of the process was investigated. From a characteristic times analysis it was concluded that the most important mechanistic steps in the acid precipitation of casein were acid mixing, aggregation/breakup, and transport in/out of the precipitate particles. Experiments in a fed batch setup using sulfuric acid as the precipitant showed how the precipitation influenced the pH profile and demonstrated the large influence of process variables, such as the acid addition rate, the mixing intensity, and aging time on particle-size distributions and the release of minerals from the casein. [source] Venous thromboembolic disease: A single-centre case series studyJOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 12 2006Fiona Newall Aim: The epidemiology of venous thromboembolism in children has likely changed since first being described a decade ago because of evolving management strategies and a greater awareness of predisposing factors for thrombosis in children. The Royal Children's Hospital commenced a 4-year prospective registry of venous thrombosis in 1999 to determine the current Australian epidemiology of venous thrombosis in infants and children. Methods: A prospective, single-centre registry was established to determine the prevalence, aetiology, diagnostic criteria, management and outcome of venous thromboembolism in an Australian tertiary paediatric centre. Results: The incidence of venous thrombosis was 8.0/10 000 hospital admissions. Fifty-eight per cent of infants and 49% of children were male. Seventy-seven per cent of venous thromboses in infants were associated with central venous cannulation compared with 47% in children. Doppler ultrasonography was the most frequently used diagnostic tool. Treatment strategies varied between age groups. The all-cause mortality rate for infants and children in this study was 8.4% (direct thrombus-related mortality 0%). Fifteen per cent of all patients demonstrated complete resolution of their venous thrombosis at discharge, with 48% demonstrating complete resolution at follow-up assessment. Fifteen per cent of patients experienced significant thrombosis-related morbidity at follow-up assessment. Conclusion: In this single-centre registry, venous thrombosis in infants and children occurred with greater frequency than has previously been reported and its epidemiology varied. Central venous catheterisation continues to be a common precipitant to venous thrombosis. Optimal diagnostic and treatment interventions for venous thromboembolism have not yet been determined for infants and children, despite the significant incidence of long-term sequelae. [source] Fabrication and Luminescent Properties of Nd3+ -Doped Lu2O3 Transparent Ceramics by Pressureless SinteringJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2009Ding Zhou The fabrication of transparent Nd3+ ion-doped Lu2O3 ceramics is investigated by pressureless sintering under a flowing H2 atmosphere. The starting Nd-doped Lu2O3 nanocrystalline powder is synthesized by a modified coprecipitant processing using a NH4OH+NH4HCO3 mixed solution as the precipitant. The thermal decomposition behavior of the precipitate precursor is studied by thermogravimetric analysis and differential thermal analysis. After calcination at 1000°C for 2 h, monodispersed Nd3+:Lu2O3 powder is obtained with a primary particle size of about 40 nm and a specific surface area of 13.7 m2/g. Green compacts, free of additives, are formed from the as-synthesized powder by dry pressing followed by cold isostatic pressing. Highly transparent Nd3+:Lu2O3 ceramics are obtained after being sintered under a dry H2 atmosphere at 1880°C for 8 h. The linear optical transmittance of the polished transparent samples with a 1.4 mm thickness reaches 75.5% at the wavelength of 1080 nm. High-resolution transmission electron microscopy observations demonstrate a "clear" grain boundary between adjacent grains. The luminescent spectra showed that the absorption coefficient of the 3 at.% Nd-doped Lu2O3 ceramic at 807 nm reached 14 cm,1, while the emission cross section at 1079 nm was 6.5 × 10,20 cm2. [source] The pathophysiological basis of acute-on-chronic liver failureLIVER INTERNATIONAL, Issue 2002S Sen Abstract: The vast majority of patients that are referred to a specialist hepatological centre suffer from acute deterioration of their chronic liver disease. Yet, this entity of acute-on-chronic liver failure remains poorly defined. With the emergence of newer liver support strategies, it has become necessary to define this entity, its pathophysiology and the short and long-term prognosis. This review focuses upon how a precipitant such as an episode of gastrointestinal bleeding or sepsis may start a cascade of events that culminate in end-organ dysfunction and liver failure. We briefly review the pathophysiological basis of the therapeutic modalities that are available. Our current strategy for the management of liver failure involves supportive therapy for the end-organs with the hope that the liver function would recover if sufficient time for such a recovery is allowed. Because liver failure, whether of the acute or acute-on-chronic variety, is potentially reversible, the stage is set for the application of newer liver support strategies to enhance the recovery process. [source] Liquid Chromatography of Synthetic Polymers under Limiting Conditions of Insolubility IIIMACROMOLECULAR SYMPOSIA, Issue 1 2007Application of Monolithic Columns Abstract Summary Performance was evaluated of silica based commercial monolithic rod-like columns in liquid chromatography of synthetic polymers under limiting conditions of enthalpic interactions (LC LC). LC LC employs the barrier effect of the pore permeating and therefore slowly eluting small molecules toward the pore excluded, fast eluting macromolecules. Phase separation (precipitation) barrier action was applied in present study. The barrier was created either by the narrow pulse of an appropriate nonsolvent injected into the column just before the sample solution (LC LC of insolubility , LC LCI) or by the eluent itself. In the latter case, the polymer sample was dissolved and injected in a good solvent (LC LC of solubility , LC LCS). In LC LCI, polymer species cannot break thru the nonsolvent zone while in LC LCS they cannot enter eluent, which is their precipitant. Therefore, polymer species keep moving in the zone of their original solvent. Macromolecules eluting under the LC LC mechanism leave the column in the retention volume (VR) roughly corresponding to VR of the low molar mass substances and can be efficiently separated from the polymer species non-hindered by the barrier action. The known advantages of monoliths were confirmed. From the point of view of LC LCI and LC LCS the most important quality of monolithic columns represents their excellent permeability, which allows both working at high flow rates and injecting very high (in the range of 5%) sample concentrations. Monolithic column tolerate also extremely high molar mass samples (M>10,000 kg,·,mol,1). On the other hand, the mesopores (separation pores) of the tested monoliths exhibited rather small volume and wide size distribution. These shortcomings partially impair the permeability advantage of monoliths because in order to obtain high LC LC separation selectivity a tandem of several monolithic columns must be applied. Presence of large mesopores also reduces applicability of monolithic columns for molar masses below about 50 kg,·,mol,1 because VRs of polymers eluted behind the barrier are similar to that of freely eluting species. The non- negligible break-thru phenomenon was observed for the very high polymer molar masses largely eluting behind the barrier. It is assumed that the fraction of very large mesopores present in the monoliths or association/microphase separation of macromolecules may be responsible for this phenomenon. This is why the presently marketed SiO2 monolithic columns are mainly suitable for the fast purification of the LC LC eluting macromolecules from the polymeric admixtures non-hindered by the barrier-forming liquid. Still, monolithic columns have large potential in the LC LCI and LC LCS procedures provided size (effective diameter) of the mesopores can be reduced and their volume increased. [source] A crystallization screen based on alternative polymeric precipitantsACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2010Clemens Grimm Most commercially available crystallization screens are sparse-matrix screens with a predominance of inorganic salts and polyethylene glycols (PEGs) as precipitants. It was noted that commercially available screens are largely unsatisfactory for the purpose of the crystallization of multimeric protein and protein,nucleic acid complexes. This was reasoned to be a consequence of the redundancy in screening crystallization parameter space by the predominance of PEG as a precipitant in standard screens and it was suggested that this limitation could be overcome by introducing a variety of other organic polymers. Here, a set of 288 crystallization conditions was devised based on alternative polymeric precipitants and tested against a set of 20 different proteins/complexes; finally, a screen comprising the 96 most promising conditions designed to complement PEG- and salt-based commercial screens was proposed. [source] The effect of protein,precipitant interfaces and applied shear on the nucleation and growth of lysozyme crystalsACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2009Nuno M. Reis This paper is concerned with the effect of protein,precipitant interfaces and externally applied shear on the nucleation and growth kinetics of hen egg-white lysozyme crystals. The early stages of microbatch crystallization of lysozyme were explored using both optical and confocal fluorescence microscopy imaging. Initially, an antisolvent (precipitant) was added to a protein drop and the optical development of the protein,precipitant interface was followed with time. In the presence of the water-soluble polymer poly(ethylene glycol) (PEG) a sharp interface was observed to form immediately within the drop, giving an initial clear separation between the lighter protein solution and the heavier precipitant. This interface subsequently became unstable and quickly developed within a few seconds into several unstable `fingers' that represented regions of high concentration-gradient interfaces. Confocal microscopy demonstrated that the subsequent nucleation of protein crystals occurred preferentially in the region of these interfaces. Additional experiments using an optical shearing system demonstrated that oscillatory shear significantly decreased nucleation rates whilst extending the growth period of the lysozyme crystals. The experimental observations relating to both nucleation and growth have relevance in developing efficient and reliable protocols for general crystallization procedures and the controlled crystallization of single large high-quality protein crystals for use in X-ray crystallography. [source] Protein crystallization in hydrogel beadsACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2005Ronnie Willaert The use of hydrogel beads for the crystallization of proteins is explored in this contribution. The dynamic behaviour of the internal precipitant, protein concentration and relative supersaturation in a gel bead upon submerging the bead in a precipitant solution is characterized theoretically using a transient diffusion model. Agarose and calcium alginate beads have been used for the crystallization of a low-molecular-weight (14.4,kDa, hen egg-white lysozyme) and a high-molecular-weight (636.0,kDa, alcohol oxidase) protein. Entrapment of the protein in the agarose-gel matrix was accomplished using two methods. In the first method, a protein solution is mixed with the agarose sol solution. Gel beads are produced by immersing drops of the protein,agarose sol mixture in a cold paraffin solution. In the second method (which was used to produce calcium alginate and agarose beads), empty gel beads are first produced and subsequently filled with protein by diffusion from a bulk solution into the bead. This latter method has the advantage that a supplementary purification step is introduced (for protein aggregates and large impurities) owing to the diffusion process in the gel matrix. Increasing the precipitant, gel concentration and protein loading resulted in a larger number of crystals of smaller size. Consequently, agarose as well as alginate gels act as nucleation promoters. The supersaturation in a gel bead can be dynamically controlled by changing the precipitant and/or the protein concentration in the bulk solution. Manipulation of the supersaturation allowed the nucleation rate to be varied and led to the production of large crystals which were homogeneously distributed in the gel bead. [source] Crystallization and preliminary X-ray crystallographic analysis of a non-specific lipid-transfer protein with antipathogenic activity from Phaseolus mungoACTA CRYSTALLOGRAPHICA SECTION D, Issue 12-2 2004Shao-Yun Wang A 9,kDa non-specific lipid-transfer protein (nsLTP) from mung bean (Phaseolus mungo) seeds, displaying antifungal activity, antibacterial activity and lipid-transfer activity, was crystallized at 297,K using ammonium sulfate as a precipitant by means of the hanging-drop vapour-diffusion method. Native X-ray diffraction data were collected to a resolution of 2.4,Å. The crystals are rhombohedral, belonging to space group P212121, with unit-cell parameters a = 38.671, b = 51.785, c = 55.925,Å. Assuming the presence of one molecule in the crystallographic asymmetric unit results in a Matthews coefficient (VM) of approximately 3.0,Å3,Da,1, corresponding to a solvent content of about 58%. [source] Crystallization and preliminary X-ray crystallographic study of leucyl-tRNA synthetase from the archaeon Pyrococcus horikoshiiACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2004Ryuya Fukunaga The leucyl-tRNA synthetase (LeuRS) from the archaeon Pyrococcus horikoshii was overexpressed in a C-terminally truncated form in Escherichia coli, purified and crystallized by the hanging-drop vapour-diffusion method using ammonium sulfate as a precipitant. The crystals belong to the rhombohedral space group R3, with unit-cell parameters a = b = 186.20, c = 91.43,Å, , = , = 90, , = 120°. The asymmetric unit contains one molecule of LeuRS, with a corresponding crystal volume per protein weight of 3.2,Å3,Da,1 and a solvent content of 60.7%. A data set diffracting to 2.2,Å resolution was collected from a single crystal at 100,K. Selenomethionine-substituted protein crystals were prepared in order to solve the structure by the SAD phasing method. [source] Crystallization and preliminary X-ray analysis of Escherichia coli MutT in binary and ternary complex formsACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2004Teruya Nakamura During replication, Escherichia coli MutT prevents the misincorporation of mutagenic 8-oxoguanine into nascent DNA strands opposite adenine by hydrolyzing 8-oxo-dGTP in nucleotide pools to 8-oxo-dGMP. E. coli MutT is the most widely investigated member of the Nudix hydrolase family, which is large and found in all organisms. By co-crystallization of MutT with 8-oxo-dGMP, a reaction product, crystals of the binary complex were obtained using ammonium sulfate as a precipitant. The crystals belong to space group P212121, with unit-cell parameters a = 37.9, b = 56.0, c = 59.4,Å. Assuming the presence of one protein,nucleotide complex in the asymmetric unit, the Matthews coefficient VM is 2.1,Å3,Da,1. Crystals of the ternary complex were prepared by soaking crystals of the binary complex in 1,mM MnCl2 solution. They diffracted to 1.96 and 2.56,Å resolution, respectively. [source] Expression, purification, crystallization and preliminary X-ray diffraction data of methylmalonate-semialdehyde dehydrogenase from Bacillus subtilisACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2004Hélène Dubourg Methylmalonate-semialdehyde dehydrogenase from Bacillus subtilis was cloned and overexpressed in Escherichia coli. Suitable crystals for X-ray diffraction experiments were obtained by the hanging-drop vapour-diffusion method using ammonium sulfate as precipitant. The crystals belong to space group P212121, with unit-cell parameters a = 195.2, b = 192.5, c = 83.5,Å, and contain one tetramer per asymmetric unit. X-ray diffraction data were collected to 2.5,Å resolution using a synchrotron-radiation source. The crystal structure was solved by the molecular-replacement method. [source] Crystallization and preliminary X-ray diffraction study of mammalian mitochondrial seryl-tRNA synthetaseACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2004Sarin Chimnaronk The mitochondrial seryl-tRNA synthetase (mt SerRS) from Bos taurus was overexpressed in Escherichia coli and crystallized using the sitting-drop vapour-diffusion method. Crystals grew in a very narrow range of conditions using PEG 8000 as precipitant at room temperature. An appropriate concentration of lithium sulfate was critical for crystal nucleation. Crystals diffracted well beyond a resolution of 1.6,Å and were found to belong to the orthorhombic space group C2221, with unit-cell parameters a = 79.89, b = 230.42, c = 135.60,Å. There is one dimer (Mr, 113,kDa) in the asymmetric unit, with a solvent content of 55%. Efforts to solve the phase problem by molecular replacement are under way. [source] Detection of l -lactate in polyethylene glycol solutions confirms the identity of the active-site ligand in a proline dehydrogenase structureACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2004Min Zhang Polyethylene glycol (PEG) is often used in protein crystallography as a low-ionic-strength precipitant for crystallization and as a cryoprotectant for low-temperature data collection. Prompted by the discovery of an apparent l -lactate molecule bound in the active site of the Escherichia coli PutA proline dehydrogenase domain crystal structure, the l -lactate concentration of several PEG solutions was measured. 50%(w/v) solutions of PEGs with molecular weight 3000, 4000 and 8000 contain millimolar levels of l -lactate. In contrast, l -lactate was not detected in solutions of PEG monomethyl ethers or PEG 3350. These results help to explain why l -lactate was present in the proline dehydrogenase domain crystal structure. This work also has implications for the crystallization of enzymes that bind l -lactate. [source] Purification, crystallization and preliminary X-ray analysis of uridine phosphorylase from Salmonella typhimuriumACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2004Mariya V. Dontsova The structural udp gene encoding uridine phosphorylase (UPh) was cloned from the Salmonella typhimurium chromosome and overexpressed in Escherichia coli cells. S. typhimurium UPh (StUPh) was purified to apparent homogeneity and crystallized. The primary structure of StUPh has high homology to the UPh from E. coli, but the enzymes differ substantially in substrate specificity and sensitivity to the polarity of the medium. Single crystals of StUPh were grown using hanging-drop vapor diffusion with PEG 8000 as the precipitant. X-ray diffraction data were collected to 2.9,Å resolution. Preliminary analysis of the diffraction data indicated that the crystal belonged to space group P61(5), with unit-cell parameters a = 92.3, c = 267.5,Å. The solvent content is 37.7% assuming the presence of one StUPh hexamer per asymmetric unit. [source] Purification, crystallization and preliminary X-ray diffraction analysis of human oncoprotein SET/TAF-1,ACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2004Shinsuke Muto The human oncoprotein SET/TAF-1, has been crystallized by the sitting-drop vapour-diffusion method using ammonium sulfate as a precipitant. The crystal belongs to space group C2, with unit-cell parameters a = 119.6, b = 62.8, c = 61.0,Å, , = 89.7°, and contains two molecules in the asymmetric unit. A complete data set was collected to 2.8,Å resolution using synchrotron radiation. [source] Crystallization and preliminary X-ray analysis of a novel Trichoderma reesei xylanase IV belonging to glycoside hydrolase family 5ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2004Tarja Parkkinen Xylanase IV (XYN IV) is a new recently characterized xylanase from Trichoderma reesei. It is able to degrade several different xylans, mainly producing xylose. XYN IV has been crystallized by the hanging-drop vapour-diffusion method, using PEG 6000 as a precipitant. The crystals belong to the orthorhombic space group P212121, with unit-cell parameters a = 86.3, b = 137.5, c = 196.1,Å, , = , = , = 90°. Assuming a molecular weight of 50.3,kDa, the VM values indicate there to be four XYN IV monomers in an asymmetric unit and the solvent content of the crystals to be 57%. Based on dynamic light-scattering measurements, XYN IV is a dimer in solution. A native data set to 2.8,Å resolution has been collected at a home laboratory and a data set to 2.2,Å resolution has been collected using synchrotron radiation. [source] Crystallization and preliminary X-ray analysis of inorganic pyrophosphatase from the hyperthermophilic archaeon Pyrococcus horikoshii OT3ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2004Binbin Liu Inorganic pyrophosphatase (PPase; EC 3.6.1.1) from the hyperthermophile Pyrococcus horikoshii was crystallized by the hanging-drop vapour-diffusion method at pH 5.0 using polyethyleneglycol 4000 as the precipitant. The crystal belongs to space group P21212, with unit-cell parameters a = 71.7, b = 86.5, c = 92.5,Å, , = , = , = 90°. There are two molecules in the asymmetric unit. The crystals were stable during exposure to X-rays and a full set of X-ray diffraction data was collected to 2.7,Å resolution in-house. [source] Crystallization and preliminary crystallographic data of a leucotoxin S component from Staphylococcus aureusACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2004Valérie Guillet Class S proteins of staphylococcal bicomponent pore-forming leucotoxins play an important role in membrane targetting and cell specificity. Wild-type and recombinant S components of the Panton,Valentine leucocidin (LukS-PV) were expressed in Staphylococcus aureus and Escherichia coli, respectively, and purified. Both proteins were crystallized in two crystal forms with Jeffamine M-600 as the precipitant at 285,K using the hanging-drop vapour-diffusion method and seeding techniques. Crystals belong to space group P2 (or P21) and P41 (or P43), with unit-cell parameters a = 72.3, b = 95.1, c = 108.1,Å, , = 106.4° and a = b = 94.8, c = 306.2,Å, respectively. A full set of X-ray diffraction data was collected to 2.1,Å from a single tetragonal crystal of the wild-type protein at 100,K. [source] Cloning, purification, crystallization and preliminary crystallographic studies of Bradyrhizobium fucosyltransferase NodZACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2004Krzysztof Brzezinski The ,-1,6-fucosyltransferase NodZ from Bradyrhizobium sp. WM9 (Lupinus), composed of 325 amino acids with a molecular weight of 37,kDa, has been cloned, expressed and purified. Protein crystals suitable for X-ray diffraction were obtained under optimized crystallization conditions using ammonium dihydrogen phosphate as a precipitant. The crystals are hexagonal and belong to space group P6122 or P6522, with unit-cell parameters a = 125.5, c = 95.6,Å, and contain 56.8% solvent and a single protein molecule in the asymmetric unit. Native data were collected to 2.85,Å using synchrotron radiation and cryogenic conditions. The native crystals were soaked in a mother-liquor solution containing 2.5,mM [Ta6Br12]2+ cluster for derivatization and SAD data were collected to 3.4,Å at the tantalum LIII absorption peak. [source] Crystallization and preliminary X-ray crystallographic analysis of the RecR protein from Deinococcus radiodurans, a member of the RecFOR DNA-repair pathwayACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2004Byung Il Lee The RecR protein plays a key role in the RecFOR pathway of recombination, which is necessary for the repair of ssDNA gaps. RecR from Deinococcus radiodurans has been overexpressed in Escherichia coli and crystallized at 297,K using polyethylene glycol 1000 as a precipitant. X-ray diffraction data to 2.90,Å resolution have been collected at 100,K using Cu,K, X-rays from a mercury-soaked crystal. The crystal belongs to space group C2221, with unit-cell parameters a = 106.96, b = 122.25, c = 156.01,Å. The asymmetric unit contains four monomers of RecR, with a crystal volume per protein weight (VM) of 2.57,Å3,Da,1 and a solvent content of 51.0%. [source] Expression, crystallization and preliminary X-ray crystallographic studies of Arthrobacter globiformis inulin fructotransferaseACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2003Mitsuru Momma A recombinant form of Arthrobacter globiformis inulin fructotransferase (DFAIII-producing) has been overexpressed in Escherichia coli and purified to homogeneity. Crystals were obtained at 293,K by the hanging-drop vapour-diffusion technique using 0.1,M Na HEPES pH 7.5 buffer containing 1.5,M lithium sulfate as a precipitant. Crystals of the recombinant wild-type enzyme diffracted to better than 1.5,Å at 100,K using a synchrotron-radiation source at the Photon Factory. The crystal belonged to space group R32, with unit-cell parameters a = b = 92.02, c = 229.82,Å in the hexagonal axes. Assuming the presence of one molecule in the asymmetric unit, the VM value for the crystal was 2.15,Å3,Da,1, indicating a solvent content of 42.8%. Selenomethionine-derivative crystals belonged to a different space group, C2, with unit-cell parameters a = 159.32, b = 91.92, c = 92.58,Å, , = 125.06. Matthews coefficient calculations suggested that the C2 selenomethionine-derivative crystal contained three molecules per asymmetric unit. [source] Crystallization and preliminary X-ray analysis of inorganic polyphosphate/ATP-glucomannokinase from Arthrobacter sp. strain KMACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2003Takako Mukai Inorganic polyphosphate [poly(P)]/ATP-glucomannokinase from Arthrobacter sp. strain KM phosphorylates glucose and mannose, utilizing both ATP and poly(P) as phosphoryl donors. The enzyme was overexpressed in Escherichia coli, purified and crystallized by means of the hanging-drop vapour-diffusion method with ammonium sulfate as the precipitant. The crystals were orthorhombic and belonged to space group P212121, with unit-cell parameters a = 66.2, b = 83.7, c = 103.8,Å. Assuming two molecules per asymmetric unit, Vsol is 0.49. X-ray diffraction data to 2.83,Å have been collected from a single crystal. [source] Crystallization and preliminary X-ray diffraction analysis of KsgA, a universally conserved RNA adenine dimethyltransferase in Escherichia coliACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2003Heather C. O'Farrell The bacterial enzyme KsgA catalyzes the transfer of a total of four methyl groups from S -adenosylmethionine (SAM) to two adjacent adenosines in 16S rRNA. These modified adenosines are universally conserved in all species of eubacteria, eukaryotes and archaebacteria studied. Recombinant KsgA from Escherichia coli was overexpressed as a His-tagged fusion protein and purified. The recombinant protein was crystallized using PEG 4000 as a precipitant. The crystals belong to space group C2 and diffract X-rays to a resolution of 1.9,Å. The unit-cell parameters are a = 173.9, b = 38.4, c = 83.0,Å, , = 90.0°. Structure determination using the molecular-replacement method is at the early stages of refinement. [source] Crystallization and preliminary X-ray characterization of a novel calcium-binding protein AtCBL2 from Arabidopsis thalianaACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2003Masamichi Nagae A new family of calcineurin B-like calcium-binding proteins has recently been identified in Arabidopsis thaliana. AtCBL2, a member of this family, has been crystallized in the presence of calcium ions using polyethylene glycol as a precipitant at 293,K. The crystals belong to space group C2221, with unit-cell parameters a = 83.9, b = 118.1, c = 49.1,Å. The asymmetric unit contains one molecule, with a VM of 2.36,Å3,Da,1 and a solvent content of 48%. Native diffraction data to 2.1,Å resolution have been collected using synchrotron radiation at SPring-8. [source] Crystallization and preliminary crystallographic analysis of extracellular fragment X3 of YWK-II/APPH: a human sperm membrane protein related to the Alzheimer ,A4-amyloid precursor proteinACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2003Wangjun Hu Crystals of extracellular fragment X3 of a human sperm membrane protein YWK-II/APPH have been grown at 291,K using 8% PEG 4000 as precipitant by the vapour-diffusion method. The diffraction pattern of the crystal extends to 2.9,Å resolution at 100,K using Cu,K, radiation in-house. The crystals belong to space group P21, with unit-cell parameters a = 46.0, b = 43.7, c = 90.2,Å, , = , = 90.0, , = 106.6°. Furthermore, a selenomethionine (SeMet) derivative of the protein was overexpressed in the same expression system and was purified in a reducing environment. The derivative crystals were obtained under similar conditions. Subsequently, a single-wavelength data set was collected to 2.38,Å resolution from the derivative crystal at ESRF. The crystals belong to space group P21, with unit-cell parameters a = 46.2, b = 44.0, c = 88.3,Å, , = , = 90.0, , = 103.6°. The presence of one molecule per asymmetric unit gives a crystal volume per protein mass (VM) of 2.8,Å3,Da,1 and a solvent content of 56.4% by volume. [source] Crystallization and preliminary X-ray analysis of NADP(H)-dependent alcohol dehydrogenases from Saccharomyces cerevisiae and Rana pereziACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2003Eva Valencia Different crystal forms diffracting to high resolution have been obtained for two NADP(H)-dependent alcohol dehydrogenases, members of the medium-chain dehydrogenase/reductase superfamily: ScADHVI from Saccharomyces cerevisiae and ADH8 from Rana perezi. ScADHVI is a broad-specificity enzyme, with a sequence identity lower than 25% with respect to all other ADHs of known structure. The best crystals of ScADHVI diffracted beyond 2.8,Å resolution and belonged to the trigonal space group P3121 (or to its enantiomorph P3221), with unit-cell parameters a = b = 102.2, c = 149.7,Å, , = 120°. These crystals were produced by the hanging-drop vapour-diffusion method using ammonium sulfate as precipitant. Packing considerations together with the self-rotation function and the native Patterson map seem to indicate the presence of only one subunit per asymmetric unit, with a volume solvent content of about 80%. ADH8 from R. perezi is the only NADP(H)-dependent ADH from vertebrates characterized to date. Crystals of ADH8 obtained both in the absence and in the presence of NADP+ using polyethylene glycol and lithium sulfate as precipitants diffracted to 2.2 and 1.8,Å, respectively, using synchrotron radiation. These crystals were isomorphous, space group C2, with approximate unit-cell parameters a = 122, b = 79, c = 91,Å, , = 113° and contain one dimer per asymmetric unit, with a volume solvent content of about 50%. [source] Crystallization and preliminary crystallographic analysis of a partial extracellular fragment of a sperm membrane protein YWK-II/APPH related to the Alzheimer ,A4-amyloid precursor proteinACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2003Maojun Yang Crystals of a partial extracellular fragment of a human sperm membrane protein YWK-II/APPH have been grown at 291,K using PEG 4000 as precipitant. The diffraction pattern of the crystal extends to 2.8,Å resolution at 100,K using Cu,K, radiation. The crystals belong to space group P212121, with unit-cell parameters a = 46.009, b = 67.387, c = 149.241,Å, , = , = , = 90°. The presence of two molecules per asymmetric unit gives a crystal volume per protein mass (VM) of 3.51,Å3,Da,1 and a solvent content of 64.6% by volume. A full set of X-ray diffraction data were collected to 2.8,Å resolution from the native crystal. [source] | |||||||||||||||||||