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Mother Liquor (mother + liquor)
Selected AbstractsIndoloquinolines, Indolobenzoxazines and Quinazolophthalazines Prepared from Norbornane/eneamino Acids and Hydrazides,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2005Géza Stájer Abstract The reactions of di -endo - and di -exo -aminonorbornane/enecarboxylic acids 1,4 with ethyl 2-(2-oxocyclohexyl)acetate afforded methanoindoloquinolines 5, 6, 8, and 9, the oxo ester participating as a two-membered sp2 building block. In the cases of di -exo - and di -endo -aminonorbornenecarboxylic acids 2 and 4, methanoindolobenzoxazinediones 7 and 10 were also formed; compound 7 was also isolated from the mother liquor of 10. The reactions of ethyl 2-(2-oxocyclohexyl)acetate with aminonorbornane/enecarbohydrazides 11,14 result in the methanoquinazolophthalazines 15,18. The structures of the compounds were elucidated by NMR spectroscopy, and for 6, 7, 8, and 10 also by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Effect of compressibility on performance of hydraulic wash columnsAICHE JOURNAL, Issue 7 2002L. van Oord-Knol In a hydraulic wash column the solid crystals are separated from the mother liquor by filtration in the top section of the column. Remaining impurities are removed via countercurrent washing of the crystals in the bottom section. Since compressibility limits the capacity of a wash column, this phenomenon needs to be quantified and modeled rigorously. The compressibility of the bed was determined from the porosity profile and the liquid-pressure profile inside the wash column. The porosity of the bed decreases from 0.65 to 0.3 during transport of the bed. This is associated with a decrease in local bed permeability by a factor of 10. The compressibility of the bed, therefore, partly explains the large ratio between the average permeability above and below the wash front. Compressibility coefficients make it possible to relate the compressive stress to the porosity and permeability in the top section of the bed. These coefficients are, therefore, incorporated in a model to successfully predict the capacity of a wash column with a compressible bed. [source] A neutron crystallographic analysis of T6 porcine insulin at 2.1,Å resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2009Wakari Iwai Neutron diffraction data for T6 porcine insulin were collected to 2.1,Å resolution from a single crystal partly deuterated by exchange of mother liquor. A maximum-likelihood structure refinement was undertaken using the neutron data and the structure was refined to a residual of 0.179. The hydrogen-bonding network of the central core of the hexamer was observed and the charge balance between positively charged Zn ions and their surrounding structure was interpreted by considering the protonation and/or deprotonation states and interactions of HisB10, water and GluB13. The observed double conformation of GluB13 was essential to interpreting the charge balance and could be compared with the structure of a dried crystal of T6 human insulin at 100,K. Differences in the dynamic behaviour of the water molecules coordinating the upper and lower Zn ions were observed and interpreted. The hydrogen bonds in the insulin molecules, as well as those involving HisB10 and GluB13, are discussed. The hydrogen/deuterium (H/D) exchange ratios of the amide H atoms of T6 porcine insulin in crystals were obtained and showed that regions highly protected from H/D exchange are concentrated in the centre of a helical region of the B chains. From the viewpoint of soaking time versus H/D-exchange ratios, the amide H atoms can be classified into three categories. [source] When less is more: a more efficient vapour-diffusion protocolACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2003Kirsty V. Dunlop Reducing protein consumption during crystallization screening is of utmost importance to crystallographers because of the time, effort and money that goes into producing pure protein. One approach is to reduce sample volumes with robotics, but a patent and the high cost of equipment limits access. Here, it is shown that the same result can be obtained by reducing the sample concentration in a modified vapour-diffusion protocol, the dilution method. In this protocol, the protein and mother liquor in the crystallization drop are both diluted, while the mother liquor in the well remains undiluted. Vapour diffusion will shrink the initial volume of the crystallization drop, e.g. 1,µl or more, to a drop size equivalent to one dispensed by a robot. This new crystallization method circumvents some of the current problems associated with robotic crystallization screening trials. Because of the large initial volume of the crystallization drop, the evaporation problem is eliminated and dispensing accuracy is improved. In addition, the likelihood that the crystallization experiment starts in the undersaturated region is increased. [source] Crystallization of the 43,kDa ATPase domain of Thermus thermophilus gyrase B in complex with novobiocinACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2002V. Lamour The 43,kDa ATPase domain of Thermus thermophilus gyrase B was overproduced in Escherichia coli and a three-step purification protocol yielded large quantities of highly purified enzyme which remained stable for weeks. Crystals of the 43,kDa domain in complex with novobiocin, one of the most potent inhibitors of bacterial topoisomerases, were obtained. Crystals obtained in the presence of PEG 8000 do not diffract, but a different crystal form was obtained using sodium formate as a precipitating agent. The plate-shaped crystals, which were less than 10,µm in thickness, could be cryocooled directly from the mother liquor and a full diffraction data set was collected to 2.3,Å allowing the determination of the first structure of a gyrase B 43K domain in complex with a coumarin. [source] Atomic force microscopy applications in macromolecular crystallographyACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2001A. McPherson Atomic force microscopy (AFM) can be applied both in situ and ex situ to study the growth of crystals from solution. The method is particularly useful for investigating the crystallization of proteins, nucleic acids and viruses because it can be carried out in the mother liquor and in a non-perturbing fashion. Interactions and transformations between various growth mechanisms can be directly visualized as a function of supersaturation, as can the incorporation of diverse impurities and the formation and propagation of defects. Because the crystals can be observed over long periods, it is also possible to obtain precise quantitative measures of the kinetic parameters for nucleation and growth. Finally, AFM has allowed us to identify a number of previously unsuspected phenomena that influence nucleation, rate of growth and the ultimate perfection of macromolecular crystals. These are all features which are important in determining the ultimate resolution and quality of a crystal's diffraction pattern. [source] Crystallization and preliminary X-ray analysis of the chemokine-binding protein from orf virus (Poxviridae)ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2010Rafael Miguez Couñago The parapoxvirus orf virus (ORFV) encodes a chemokine-binding protein (CBP) that functions to downregulate the host's immune response at the site of infection by blocking the chemokine-induced recruitment of immune cells. In order to shed light on the structural determinants of CBP,chemokine binding, ORFV CBP was crystallized as part of an ongoing structure,function study on this protein. ORFV CBP crystals were obtained by the sitting-drop vapour-diffusion technique using ammonium citrate as a precipitant. The crystal quality was greatly improved through the addition of small-molecule additives to the crystallization mother liquor. ORFV CBP crystals diffracted X-rays to 2.50,Å resolution and belonged to the hexagonal space group P6122 or its enantiomorph P6522, with unit-cell parameters a = b = 75.62, c = 282.49,Å, , = 90, , = 90, , = 120°. [source] Synthesis of 14C-labelled EM-800 (SCH 57050) and EM-652·HCl (SCH 57068·HCl, acolbifene), pure selective estrogen receptor modulatorsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 11 2004Jean-Yves Sancéau Abstract EM-800 (SCH 57050) and EM-652·HCl (SCH 57068·HCl, acolbifene) are orally active pure selective estrogen receptor modulators. The corresponding 14C2 -radiolabelled compounds 1 and 2 were synthesized for metabolic studies with uniform labelling of two carbons within the benzene ring of the 2H-1-benzopyran moiety by optical resolution of racemic (±)-[14C2]EM-343 4. This pivotal intermediate amine was prepared in 6 steps with 38% yield from commercially available [U- 14C2]resorcinol (3). Resolution by selective crystallization of the diastereomeric mixture of (S)-(+)-camphorsulfonates salts gave the desired (+)-[14C2]EM-652·(+)-CSA 13. Moreover, the racemic amine 4 was recovered from mother liquors by basic treatment, and resolved again. We obtained salt 13, at a 52% yield with 97% diastereomeric excess by repeating the resolution,racemization process. Finally, the corresponding dipivaloate (+)-[14C2]EM-800 1 and hydrochloride salt (+)-[14C2]EM-652·HCl 2 were prepared at respective specific activities of 19.7 and 24.5 µCi/mg with 96.3% radiochemical purity. Copyright © 2004 John Wiley & Sons, Ltd. [source] Release-modulating factors strongly affecting steroid diffusion from silicone elastomer,JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2004Harold A. Nash Abstract Investigations were undertaken to determine the cause of decreases over time in the release rate from levonorgestrel (LNG) implants consisting of silicone elastomer tubing filled with crystalline steroid. Emptying and refilling with the same steroid partially restored release rate. Surprisingly, a further increment in release rates was attained if the tubing was briefly irrigated with methanol before refill. Fractional crystallization showed that release-modulating factors could be concentrated in mother liquors and were initially present as impurities. Boiling LNG in ethanol or methanol produced a number of release-modulating factors of which the most prominent was also found in one production lot of LNG. It was identified as 6,-hydroxy-levonorgestrel (6,-OH-LNG). Added to LNG at the 2% level, 6,-OH-LNG decreased the release rate by 27%. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:2420,2430, 2004 [source] Expression, purification, crystallization and preliminary X-ray analysis of the DNA-binding domain of a Chlamydia trachomatis OmpR/PhoB-subfamily response regulator homolog, ChxRACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2009John M. Hickey Two-component signal transduction systems in bacteria are a primary mechanism for responding to environmental stimuli and adjusting gene expression accordingly. Generally in these systems a sensor kinase phosphorylates a response regulator that regulates transcription. Response regulators contain two domains: a receiver domain and an effector domain. The receiver domain is typically phosphorylated and as a result facilitates the DNA-binding and transcriptional activity of the effector domain. The OmpR/PhoB subfamily is the largest of the response-regulator subfamilies and is primarily defined by the winged helix,turn,helix DNA-binding motif within the effector domain. The overall structure of effector domains is highly conserved and contains three defined elements that are critical for transcriptional regulation: a DNA major-groove binding helix, a DNA minor-groove binding wing and a transcriptional activation loop. These functional elements are often diverse in sequence and conformation and reflect the functional differences observed between individual subfamily members. ChxR from Chlamydia trachomatis is an atypical OmpR/PhoB response regulator homolog that has transcriptional activity in the absence of phosphorylation. To facilitate the precise identification of the functional elements of the ChxR effector domain, this protein was cloned, expressed, purified and crystallized. Crystals were obtained from two separate mother liquors, producing two morphologically distinct crystals. The space group of both crystals was P43212 (or its enantiomorph P41212) with isomorphous unit-cell parameters; the crystals diffracted to 2.2,2.5,Å resolution. [source] | ||||||||||