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Solubility Profiles (solubility + profile)
Selected AbstractsComparison of a miniaturized shake-flask solubility method with automated potentiometric acid/base titrations and calculated solubilitiesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2005A. Glomme Abstract Solubility is one of the most important parameters for lead selection and optimization during drug discovery. Its determination should therefore take place as early as possible in the process. Because of the large numbers of compounds involved and the very low amounts of each compound available in the early development stage, it is highly desirable to measure the solubility with as little compound as possible and to be able to improve the throughput of the methods used. In this work, a miniaturized shake-flask method was developed and the solubility results were compared with those measured by semiautomated potentiometric acid/base titrations and computational methods for 21 poorly soluble compounds with solubilities mostly in the range 0.03,30 ,g/mL. The potentiometric method is very economical (approximately 100 ,g of a poorly soluble compound is needed) and is able to create a pH/solubility profile with one single determination, but is limited to ionizable compounds. The miniaturized shake-flask method can be used for all compounds and a wide variety of media. Its precision and throughput proved superior to the potentiometric method for very poorly soluble compounds. Up to 20 compounds a week can be studied with one set-up. Calculated solubility data seem to be sufficient for a first estimate of the solubility, but they cannot currently be used as a substitute for experimental measurements at key decision points in the development process. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1,16, 2005 [source] Functional Properties of Improved Glycinin and ,-nglycinin FractionsJOURNAL OF FOOD SCIENCE, Issue 4 2004D. A. Rickert ABSTRACT: Glycinin and ,-conglycinin have unique functionality characteristics that contribute important properties in soy foods and soy ingredients. Limited functionality data have been published for glycinin and ,-conglycinin fractions produced in pilot-scale quantities. Protein extraction conditions were previously optimized for our pilotscale fractionation process to maximize protein solubilization and subsequent product recovery. Glycinin, ,-conglycinin, and intermediate (mixture of glycinin and ,-conglycinin) fractions were prepared using optimized-process (OP) extraction conditions (10:1 water-to-flake ratio, 45°C) and previous conditions termed Wu process (WP) (15:1, 20°C). Viscosity, solubility, gelling, foaming, emulsification capacity, and emulsification activity and stability of the fractionated proteins, and soy protein isolate (SPI) produced from the same defatted soy white flakes were compared to evaluate functional properties of these different protein fractions. Differential scanning calorimetry, sodium dodecylsulfate-polyacrylamide gel electrophoresis, and surface hydrophobicity data were used to interpret functionality differences. OP ,-conglycinin had more glycinin contamination than did the WP ,-conglycinin. OP and WP solubility profiles were each similar for respective glycinin and ,-conglycinin fractions. Emulsification activities and stabilities were higher for OP ,-conglycinin and OP intermediate fractions compared with respective WP fractions. ,-Conglycinin and SPI emulsification capacities (ECs) mirrored solubility profile, whereas glycinin ECs did not. OP glycinin had a higher foaming capacity than WP glycinin. OP and WP intermediate fraction apparent viscosities trended higher than those of other protein fractions. ,-Conglycinin dispersions at pH 3 and 7 produced firm gels at 80°C, whereas glycinin dispersions formed weaker gels at 99°C and did not gel at 80°C. [source] Distinct properties of murine ,5 ,-aminobutyric acid type a receptors revealed by biochemical fractionation and mass spectroscopyJOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2009Young H. Ju Abstract ,-Aminobutyric acid type A receptors (GABAARs) that contain the ,5 subunit are expressed predominantly in the hippocampus, where they regulate learning and memory processes. Unlike conventional postsynaptic receptors, GABAARs containing the ,5 subunit (,5 GABAARs) are localized primarily to extrasynaptic regions of neurons, where they generate a tonic inhibitory conductance. The unique characteristics of ,5 GABAARs have been examined with pharmacological, immunostaining, and electrophysiological techniques; however, little is known about their biochemical properties. The aim of this study was to modify existing purification and enrichment techniques to isolate ,5 GABAARs preferentially from the mouse hippocampus and to identify the ,5 subunit by using tandem mass spectroscopy (MS/MS). The results showed that the detergent solubility of the ,5 subunits was distinct from that of ,1 and ,2 subunits, and the relative distribution of the ,5 subunits in Triton X-100-soluble fractions was correlated with that of the extracellular protein radixin but not with that of the postsynaptic protein gephyrin. Mass spectrometry identified the ,5 subunit and showed that this subunit associates with multiple ,, ,, and , subunits, but most frequently the ,3 subunit. Thus, the ,5 subunits coassemble with similar subunits as their synaptic counterparts yet have a distinct detergent solubility profile. Mass spectroscopy now offers a method for detecting and characterizing factors that confer the unique detergent solubility and possibly cellular location of ,5 GABAARs in hippocampal neurons. © 2009 Wiley-Liss, Inc. [source] Mining mammalian genomes for folding competent proteins using Tat-dependent genetic selection in Escherichia coliPROTEIN SCIENCE, Issue 12 2009Hyung-Kwon Lim Abstract Recombinant expression of eukaryotic proteins in Escherichia coli is often limited by poor folding and solubility. To address this problem, we employed a recently developed genetic selection for protein folding and solubility based on the bacterial twin-arginine translocation (Tat) pathway to rapidly identify properly folded recombinant proteins or soluble protein domains of mammalian origin. The coding sequences for 29 different mammalian polypeptides were cloned as sandwich fusions between an N-terminal Tat export signal and a C-terminal selectable marker, namely ,-lactamase. Hence, expression of the selectable marker and survival on selective media was linked to Tat export of the target mammalian protein. Since the folding quality control feature of the Tat pathway prevents export of misfolded proteins, only correctly folded fusion proteins reached the periplasm and conferred cell survival. In general, the ability to confer growth was found to relate closely to the solubility profile and molecular weight of the protein, although other features such as number of contiguous hydrophobic amino acids and cysteine content may also be important. These results highlight the capacity of Tat selection to reveal the folding potential of mammalian proteins and protein domains without the need for structural or functional information about the target protein. [source] Computational Oral Absorption Simulation for Low-Solubility CompoundsCHEMISTRY & BIODIVERSITY, Issue 11 2009Kiyohiko Sugano Abstract Bile micelles play an important role in oral absorption of low-solubility compounds. Bile micelles can affect solubility, dissolution rate, and permeability. For the pH,solubility profile in bile micelles, the Henderson,Hasselbalch equation should be modified to take bile-micelle partition into account. For the dissolution rate, in the Nernst,Brunner equation, the effective diffusion coefficient in bile-micelle media should be used instead of the monomer diffusion coefficient. The diffusion coefficient of bile micelles is 8- to 18-fold smaller than that of monomer molecules. For permeability, the effective diffusion coefficient in the unstirred water layer adjacent to the epithelial membrane, and the free fraction at the epithelial membrane surface should be taken into account. The importance of these aspects is demonstrated here using several in vivo and clinical oral-absorption data of low-solubility model compounds. Using the theoretical equations, the food effect on oral absorption is further discussed. [source] Dissolution of root canal sealer cements in volatile solventsINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2000J. M. Whitworth Whitworth JM, Boursin EM. Dissolution of root canal sealer cements in volatile solvents. International Endodontic Journal, 33, 19,24, 2000. Aim There are few published data on the solubility profiles of endodontic sealers in solvents commonly employed in root canal retreatment. This study tested the hypothesis that root canal sealer cements are insoluble in the volatile solvents chloroform and halothane. Methodology Standardized samples (n=5) of glass ionomer (Ketac Endo), zinc oxide-eugenol (Tubli-Seal EWT), calcium hydroxide (Apexit) and epoxy resin (AH Plus) based sealers were immersed in chloroform or halothane for 30 s, 1 min, 5 min and 10 min. Mean loss of weight was plotted against time of exposure, and differences in behaviour assessed by multiple paired t-tests (P <0.01). Results Clear differences were shown in the solubility profiles of major classes of root canal sealer cements in two common volatile solvents. In comparison with other classes of material, Ketac Endo was the least soluble in chloroform and halothane (P <0.01), with less than 1% weight loss after 10 min exposure to either solvent. Apexit had low solubility with 11.6% and 14.19% weight loss after 10 min exposure to chloroform and halothane, respectively. The difference between solvents was not significant (P >0.01). Tubli-Seal EWT was significantly less soluble in halothane than chloroform (5.19% and 62.5% weight loss after 10 min exposure, respectively (P <0.01)). Its solubility in halothane was not significantly different from that of Apexit. AH Plus was significantly more soluble than all other materials in both chloroform and halothane (96% and 68% weight loss after 10 min exposure, respectively (P <0.01)). Conclusions There are significant differences in the solubility profiles of major classes of root canal sealer in common organic solvents. Efforts should continue to find a more universally effective solvent for use in root canal retreatment. [source] Functional Properties of Improved Glycinin and ,-nglycinin FractionsJOURNAL OF FOOD SCIENCE, Issue 4 2004D. A. Rickert ABSTRACT: Glycinin and ,-conglycinin have unique functionality characteristics that contribute important properties in soy foods and soy ingredients. Limited functionality data have been published for glycinin and ,-conglycinin fractions produced in pilot-scale quantities. Protein extraction conditions were previously optimized for our pilotscale fractionation process to maximize protein solubilization and subsequent product recovery. Glycinin, ,-conglycinin, and intermediate (mixture of glycinin and ,-conglycinin) fractions were prepared using optimized-process (OP) extraction conditions (10:1 water-to-flake ratio, 45°C) and previous conditions termed Wu process (WP) (15:1, 20°C). Viscosity, solubility, gelling, foaming, emulsification capacity, and emulsification activity and stability of the fractionated proteins, and soy protein isolate (SPI) produced from the same defatted soy white flakes were compared to evaluate functional properties of these different protein fractions. Differential scanning calorimetry, sodium dodecylsulfate-polyacrylamide gel electrophoresis, and surface hydrophobicity data were used to interpret functionality differences. OP ,-conglycinin had more glycinin contamination than did the WP ,-conglycinin. OP and WP solubility profiles were each similar for respective glycinin and ,-conglycinin fractions. Emulsification activities and stabilities were higher for OP ,-conglycinin and OP intermediate fractions compared with respective WP fractions. ,-Conglycinin and SPI emulsification capacities (ECs) mirrored solubility profile, whereas glycinin ECs did not. OP glycinin had a higher foaming capacity than WP glycinin. OP and WP intermediate fraction apparent viscosities trended higher than those of other protein fractions. ,-Conglycinin dispersions at pH 3 and 7 produced firm gels at 80°C, whereas glycinin dispersions formed weaker gels at 99°C and did not gel at 80°C. [source] Bilinear model for the prediction of drug solubility in ethanol/water mixturesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2005Stephen G. Machatha Abstract A new bilinear function that accounts for the disparity between the log-linear and parabolic models for cosolvent solubilization is presented, where ethanol was used as the model cosolvent. This accounts for both the initial and terminal slopes in the ethanol/water solubility profiles of semi-polar solutes. The proposed model has only two fitted parameters ,A and ,B, which represent the initial and terminal asymptotes in the solubility profiles. The bilinear function can also model the ethanol/water solubility profile more accurately than the log-linear model and a general parabolic model. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:2731,2735, 2005 [source] Recombinant protein expression and solubility screening in Escherichia coli: a comparative studyACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2006Nick S. Berrow Producing soluble proteins in Escherichia coli is still a major bottleneck for structural proteomics. Therefore, screening for soluble expression on a small scale is an attractive way of identifying constructs that are likely to be amenable to structural analysis. A variety of expression-screening methods have been developed within the Structural Proteomics In Europe (SPINE) consortium and to assist the further refinement of such approaches, eight laboratories participating in the network have benchmarked their protocols. For this study, the solubility profiles of a common set of 96 His6 -tagged proteins were assessed by expression screening in E. coli. The level of soluble expression for each target was scored according to estimated protein yield. By reference to a subset of the proteins, it is demonstrated that the small-scale result can provide a useful indicator of the amount of soluble protein likely to be produced on a large scale (i.e. sufficient for structural studies). In general, there was agreement between the different groups as to which targets were not soluble and which were the most soluble. However, for a large number of the targets there were wide discrepancies in the results reported from the different screening methods, which is correlated with variations in the procedures and the range of parameters explored. Given finite resources, it appears that the question of how to most effectively explore `expression space' is similar to several other multi-parameter problems faced by crystallographers, such as crystallization. [source] | ||||||||||