Home About us Contact
|
Home About us Contact | ||
|
|
||
Hydrophobic Nature (hydrophobic + nature)
Selected AbstractsAnalysis of integral membrane proteins by heat gel-embedment combined with improved in-gel digestionsELECTROPHORESIS, Issue 23 2009Jian Zhou Abstract Analysis of integral membrane proteins (IMPs) presents a special challenge because of their hydrophobic nature and low abundance. Here, a new method was developed, which involved heat gel-embedment and improved in-gel digestion of the proteins. Membrane protein lysate containing detergents was mixed with acrylamide solution and the proteins were embedded when the gel polymerized. For comparison, the protein embedment was made at different temperatures (25, 35 or 45°C), and the in-gel digestions were performed in the presence of 0.1% RapiGest reagent (ALS), 0.1% sodium deoxycholate and 10% ACN, respectively. The resultant peptides were extracted and analyzed by capillary liquid chromatography coupled with tandem mass spectrometry. Compared with that at 25°C, gel-embedment at 45°C improved the protein embedment and thus protein identification, with the identified IMPs increased by 27%. 0.1% sodium deoxycholate was more efficient than 0.1% ALS and 10% ACN in terms of improving the digestion and tryptic digest recovery of the gel-embedded proteins particularly the hydrophobic IMPs. Out of the 326 IMPs identified by heat gel-embedment combined with improved in-gel digestion strategies, 149 (46%) proteins had at least two mapped transmembrane domains. These results indicate that our newly developed protocol could facilitate the high throughput analysis of integral membrane proteome. [source] Photochemical treatment of a mixed PAH/surfactant solution for surfactant recovery and reuseENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2001Youn-Joo An Because of their hydrophobic nature, polycyclic aromatic hydrocarbons (PAHs) are generally thought to be unavailable to in situ remediation processes, and solubilization of PAHs by surfactants is usually recommended. However, mixed PAH/surfactant solutions are wastewaters that need a post-treatment after solubilization. In this study, mixed solutions of PAH and perfluorinated surfactant (PFS) were photochemically treated with and without hydrogen peroxide (H2O2), and the subsequent recovery and reuse of surfactant solutions were demonstrated. Phenanthrene and pyrene were selected as representative PAHs and lithium perfluorooctanesulfonate (LiFOS) as a PFS. Direct photolysis (UV only) and UV/H2O2 process enhanced the PAH degradation in LiFOS solutions compared to water. Both treatment processes selectively degraded PAHs without damaging PFS, suggesting that PFS withstands photolysis. Overall, it is demonstrated that UV and UV/H2O2 processes of mixed PAH/PFS solutions are effective for surfactant recovery/reuse, as well as PAH degradation. [source] Evidence for surfactant contributing to the gastric mucosal barrier of the horseEQUINE VETERINARY JOURNAL, Issue 6 2000M. T. ETHELL Summary This study was undertaken to determine the hydrophobicity of the luminal surface of the equine stomach and to elucidate the ultrastructure of the lining imparting that property. Gastric and duodenal mucosal samples from 5 horses were collected immediately after euthanasia and subjected to surface contact angle measurement using a goniometer. Gastric mucosal samples from 4 horses and a foal were examined by electron microscopy following a fixation procedure known to preserve phospholipids and oligolamellar structures. Contact angles for the equine gastric glandular mucosal surface (mean ± s.e. 78.0 ± 11.0°) were greater than for the duodenum (33.4 ± 8.7°), (P = 0.003). The contact angles for gastric squamous tissue (50.4 ± 4.5°) tended to be greater than for duodenum (P = 0.15). Electron microscopy revealed the existence of surfactant as abundant osmiophilic phospholipid material within both squamous and glandular gastric mucosae. These results indicate the hydrophobic nature of the equine gastric mucosae. We propose that the water-repellent nature of the stomach contributes to the ,gastric mucosal barrier' and is imparted by surface-active phospholipid adsorbed to the surface. Phospholipids may also be utilised as a physical barrier to back-diffusion of acid by lining intracellular canaliculi and oxyntic ducts where other defence mechanisms are absent. [source] Microbial biodegradation of polyaromatic hydrocarbonsFEMS MICROBIOLOGY REVIEWS, Issue 6 2008Ri-He Peng Abstract Polycyclic aromatic hydrocarbons (PAHs) are widespread in various ecosystems and are pollutants of great concern due to their potential toxicity, mutagenicity and carcinogenicity. Because of their hydrophobic nature, most PAHs bind to particulates in soil and sediments, rendering them less available for biological uptake. Microbial degradation represents the major mechanism responsible for the ecological recovery of PAH-contaminated sites. The goal of this review is to provide an outline of the current knowledge of microbial PAH catabolism. In the past decade, the genetic regulation of the pathway involved in naphthalene degradation by different gram-negative and gram-positive bacteria was studied in great detail. Based on both genomic and proteomic data, a deeper understanding of some high-molecular-weight PAH degradation pathways in bacteria was provided. The ability of nonligninolytic and ligninolytic fungi to transform or metabolize PAH pollutants has received considerable attention, and the biochemical principles underlying the degradation of PAHs were examined. In addition, this review summarizes the information known about the biochemical processes that determine the fate of the individual components of PAH mixtures in polluted ecosystems. A deeper understanding of the microorganism-mediated mechanisms of catalysis of PAHs will facilitate the development of new methods to enhance the bioremediation of PAH-contaminated sites. [source] Probing the interaction forces between hydrophobic peptides and supported lipid bilayers using AFMJOURNAL OF MOLECULAR RECOGNITION, Issue 6 2007Guillaume Andre Abstract Despite the vast body of literature that has accumulated on tilted peptides in the past decade, direct information on the forces that drive their interaction with lipid membranes is lacking. Here, we attempted to use atomic force microscopy (AFM) to explore the interaction forces between the Simian immunodeficiency virus peptide and phase-separated supported bilayers composed of various lipids, i.e. dipalmitoylphosphatidylcholine, dioleoylphosphatidylcholine, dioleoylphosphatidic acid and dipalmitoylphosphatidylethanolamine. Histidine-tagged peptides were attached onto AFM tips terminated with nitrilotriacetate and tri(ethylene glycol) groups, an approach expected to ensure optimal exposure of the C-terminal hydrophobic domain. Force,distance curves recorded between peptide-tips and the different bilayer domains always showed a long-range repulsion upon approach and a lack of adhesion upon retraction, in marked contrast with the hydrophobic nature of the peptide. To explain this unexpected behaviour, we suggest a mechanism in which lipids are pulled out from the bilayer due to strong interactions with the peptide-tip, in agreement with the very low force needed to extract lipids from supported bilayers. Copyright © 2007 John Wiley & Sons, Ltd. [source] Ratiometric Singlet Oxygen Nano-optodes and Their Use for Monitoring Photodynamic Therapy NanoplatformsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2005Youfu Cao ABSTRACT Ratiometric photonic explorers for bioanalysis with biologically localized embedding (PEBBLE) nanoprobes have been developed for singlet oxygen, using organically modified silicate (ORMOSIL) nanoparticles as the matrix. A crucial aspect of these ratiometric singlet-oxygen fluorescent probes is their minute size. The ORMOSIL nanoparticles are prepared via a sol-gel,based process and the average diameter of the resultant particles is about 160 nm. These sensors incorporate the singlet-oxygen,sensitive 9,10-dimethyl anthracene as an indicator dye and a singlet-oxygen,insensitive dye, octaethylporphine, as a reference dye for ratiometric fluorescence-based analysis. We have found experimentally that these nanoprobes have much better sensitivity than does the conventional singlet-oxygen,free dye probe, anthracene-9, 10-dipropionic acid disodium salt. The much longer lifetime of singlet oxygen in the ORMOSIL matrix, compared to aqueous solutions, in addition to the relatively high singlet oxygen solubility because of the highly permeable structure and the hydrophobic nature of the outer shell of the ORMOSIL nanoparticles, results in an excellent overall response to singlet oxygen. These nanoprobes have been used to monitor the singlet oxygen produced by "dynamic nanoplatforms" that were developed for photodynamic therapy. The singlet oxygen nanoprobes could potentially be used to quantify the singlet oxygen produced by macrophages. [source] Biodegradation and Biocompatibility of PolyorganophosphazeneARTIFICIAL ORGANS, Issue 10 2002Hiroyoshi Kawakami Abstract: We investigated biodegradation and biocompatibility of poly(organophosphazenes). We prepared poly(organophosphazenes) having different side chain groups. The blood compatibility of poly(organophosphazenes) containing fluorinated side groups, poly(bis[trifluoroethoxy]phosphazene) (PbFP) and poly([trifluoroethoxy][ethyl glycinate]phosphazene) (PFGP), without heparinization were evaluated in vitro. The deformation and aggregation of platelets adhered on PbFP and PFGP were not observed and they suppressed platelet activation. Additionally, PbFP and PFGP showed a higher degradation rate, despite their high hydrophobic nature. We found that the high mobility of water in PbFP and PFGP was one of the important factors facilitating their degradation. Their polymer structures were formed in a more open nature, indicating that water easily attacked the backbone of the phosphorus and nitrogen atoms in the poly(organophosphazene). On the other hand, the proliferation of HeLa cells cultured on poly(organophosphazene) was reduced compared with that on the control tissue culture polystyrene. [source] Expression, purification and preliminary crystallization of amaranth 11S proglobulin seed storage protein from Amaranthus hypochondriacus L.ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2010Mary Rose Tandang-Silvas 11S globulin is one of the major seed storage proteins in amaranth. Recombinant protein was produced as up to ,80% of the total bacterial protein using Escherichia coli Rosetta-gami (DE3) containing pET21d with amaranth 11S globulin cDNA. The best expression condition was at 302,K for 20,h using LB medium containing 0.5,M NaCl. The recombinant protein was easily separated from most of the Escherichia coli proteins by precipitation with 0,40% ammonium sulfate solution. It formed aggregates at low temperature and at low salt concentrations. This behaviour may imply that it has a more hydrophobic nature than other 11S seed globulins. The crystals diffracted to 6,Å resolution and belonged to space group P63, with unit-cell parameters a = b = 97.6, c = 74.8,Å, , = 120.0°. One subunit of a trimer was estimated to be present in the asymmetric unit, assuming a Vsol of 41%. To obtain the complete structure solution, experiments to improve crystallization and flash-cooling conditions are in progress. [source] Improved reactor performance and operability in the biotransformation of carveol to carvone using a solid,liquid two-phase partitioning bioreactorBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2008Jenna L.E. Morrish Abstract In an effort to improve reactor performance and process operability, the microbial biotransformation of (,)- trans -carveol to (R)-(,)-carvone by hydrophobic Rhodococcus erythropolis DCL14 was carried out in a two phase partitioning bioreactor (TPPB) with solid polymer beads acting as the partitioning phase. Previous work had demonstrated that the substrate and product become inhibitory to the organism at elevated aqueous concentrations and the use of an immiscible second phase in the bioreactor was intended to provide a reservoir for substrates to be delivered to the aqueous phase based on the metabolic rate of the cells, while also acting as a sink to uptake the product as it is produced. The biotransformation was previously undertaken in a two liquid phase TPPB with 1-dodecene and with silicone oil as the immiscible second phase and, although improvement in the reactor performance was obtained relative to a single phase system, the hydrophobic nature of the organism caused the formation of severe emulsions leading to significant operational challenges. In the present work, eight types of polymer beads were screened for their suitability for use in a solid,liquid TPPB for this biotransformation. The use of selected solid polymer beads as the second phase completely prevented emulsion formation and therefore improved overall operability of the reactor. Three modes of solid,liquid TPPB operation were considered: the use of a single polymer bead type (styrene/butadiene copolymer) in the reactor, the use of a mixture of polymer beads in the reactor (styrene/butadiene copolymer plus Hytrel® 8206), and the use of one type of polymer beads in the reactor (styrene/butadiene copolymer), and another bead type (Hytrel® 8206) in an external column through which fermentation medium was recirculated. This last configuration achieved the best reactor performance with 7 times more substrate being added throughout the biotransformation relative to a single aqueous phase benchmark reactor and 2.7 times more substrate being added relative to the best two liquid TPPB case. Carvone was quantitatively recovered from the polymer beads via single stage extraction into methanol, allowing for bead re-use. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc. [source] Enantioselective Proteins: Selection, Binding Studies and Molecular Modeling of Antibodies with Affinity towards Hydrophobic BINOL DerivativesCHEMBIOCHEM, Issue 16 2007Brian Schou Rasmussen Dr. Abstract In this paper, the initial steps towards the design of novel artificial metalloenzymes that exploit proteins as a second coordination sphere for traditional metal,ligand catalysis are described. Phage display was employed to select and study antibody fragments capable of recognizing hydrophobic BINOL derivatives designed to mimic BINAP, a widely used ligand in asymmetric metal-catalyzed reactions. The binding affinities of the selected antibodies towards a series of haptens were evaluated by using ELISA assays. A homology model of one of the most selective antibodies was constructed, and a computer-assisted ligand-docking study was carried out to elucidate the binding of the hapten. It was shown that, due to the hydrophobic nature of the haptens, a higher level of theoretical treatment was required to identify the correct binding modes. A small selection of the antibodies was found to discriminate between enantiomers and small structural modifications of the BINOL derivatives. The selectivities arise from hydrophobic interactions, and we propose that the identified set of antibodies provides a foundation for a novel route to artificial metalloenzymes. [source] | ||||||||||||||||