Preparation of hydrophobic cotton cloth

Summary Hydrophobic cotton cloths were prepared by heating cotton flannel in a mixture of alcohols or phenols, epichlorohydrin and 4 M NaOH. These cloths adsorbed as much bovine serum albumin as did a commercial preparation of phenyl agarose. -Galactosidase and -glucosidase adsorbed on the cloths were about 50% as active as free enzymes. Glucoamylase immobilized on naphthyl cloth in a packed bed column efficiently hydrolyzed soluble starch to glucose. These inexpensive media would be useful for commercial-scale hydrophobic chromatography and enzyme immobilization.     

Use of a hydrophobic cloth for enzyme immunoassay

Summary As an adsorbent for enzyme immunoassay, a macroporous polyester cloth was superior to the conventional non-porous microtiter plate in that it provides a much larger surface area for immunoreactions (thus, faster reactions), can accommodate a larger volume of sample, and permits easier washing. These attributes should enable polyester cloth to provide rapid and simple field assays.     

Adsorption of IgG onto hydrophobic teflon. Differences between the Fab and Fc domains

The effect of differences in the degree of hydrophobicity of protein patches/fragments on the adsorption behaviour of the protein is investigated. The adsorption isotherm of a monoclonal mouse anti-human immunoglobulin G (isotype 2b) onto hydrophobic Teflon particles is measured using a depletion method. The adsorption-induced denaturation of the immunoglobulin as a function of the adsorbed amount is studied by differential scanning calorimetry, and the corresponding rearrangements in the secondary structure of the whole IgG molecule and its F_ab and F_c fragments are determined by circular dichroism spectroscopy. The effects of adsorption on the F_ab and F_c fragments in the intact IgG molecule occur independently. Adsorption of the whole IgG molecule leads to denaturation of the F_ab fragments, whereas the F_c fragment remains unperturbed; adsorption of the isolated fragments results in structural changes in both F_ab and F_c. The surface hydrophobicity of the isolated fragments was studied by HPLC. These experiments support the hypothesis that differences in the degree of denaturation between F_ab and F_c are due to the higher degree of hydrophobicity of the F_ab fragment. The adsorption-induced changes in the secondary structure are more prominent for the isolated fragments as compared to intact IgG. This is ascribed to the higher flexibility of the isolated fragment, as compared to the fragment in the whole molecule.     

Improved conversion of fumarate to succinate by Escherichia coli strains amplified for fumarate reductase

Two recombinant plasmid Escherichia coli strains containing amplified fumarate reductase activity converted fumarate to succinate at significantly higher rates and yields than a wild-type E. coli strain. Glucose was required for the conversion of fumarate to succinate, and in the absence of glucose or in cultures with a low cell density, malate accumulated. Two-dimensional gel electrophoretic analysis of proteins from the recombinant DNA and wild-type strains showed that increased quantities of both large and small fumarate reductase subunits were expressed in the recombinant DNA strains.     

Improved conversion of fumarate to succinate by Escherichia coli strains amplified for fumarate reductase.

Two recombinant plasmid Escherichia coli strains containing amplified fumarate reductase activity converted fumarate to succinate at significantly higher rates and yields than a wild-type E. coli strain. Glucose was required for the conversion of fumarate to succinate, and in the absence of glucose or in cultures with a low cell density, malate accumulated. Two-dimensional gel electrophoretic analysis of proteins from the recombinant DNA and wild-type strains showed that increased quantities of both large and small fumarate reductase subunits were expressed in the recombinant DNA strains.     

Photovoltaic conversion using Zn chlorophyll derivative assembled in hydrophobic domain onto nanocrystalline TiO2 electrode

Photovoltaic conversion using zinc chlorin-e6 (ZnChl-e6), which is zinc chlorophyll-a derivative, and fatty acid (myristic acid or cholic acid) co-adsorbed nanocrystalline TiO2 layer onto ITO glass (OTE) electrode is developed. The maximum peaks of photocurrent action spectrum of the ZnChl-e6 adsorbed TiO2 layer onto OTE (ZnChl-e6/TiO2) are 400, 660 and 800 nm, respectively. Especially the IPCE value at 800 nm (7.5%) is larger than that of 660 nm (6.9%). This result indicates that ZnChl-e6 molecules is aggregated or formed dimer on a nanocrystalline TiO2 layer onto OTE and the absorption band is shifted to near IR region. The photocurrent action spectrum of ZnChl-e6 and cholic acid adsorbed TiO2 layer onto OTE (ZnChl-e6-Cho/TiO2 is similar to that of the UV-vis absorption spectrum in methanol solution, and IPCE values at 400 and 660 nm (8.1%) increase and the IPCE value at 800 nm (4.1%) decreases, indicating that the aggregation of ZnChl-e6 molecules on the TiO2 is suppressed by cholic acid. By using ZnChl-e6-Cho/TiO2, the short-circuit photocurrent density and open-circuit photovoltage also increase compared with that of ZnChl-e6 adsorbed nanocrystalline TiO2 electrode.     

Adsorption of a hydrophobic bacterium onto hematite: Implications in the froth flotation of the mineral

Summary The present study reports on the relationship between adsorption ofMycobacterium phlei onto hematite and flotation of the mineral. From light and scanning electron microscopy, contact angle and electrophoretic mobility observations it was found thatM. phlei is more negatively charged than hematite, that it readily accumulates onto the mineral and that it functions as a flotation collector for the mineral with optimum flotation taking place at about pH 2.5.     

Production of l-alanine from ammonium fumarate using two immobilized microorganisms

Summary For the efficient production of l-alanine from ammonium fumarate using the aspartase activity of immobilized Escherichia coli cells and l-aspartate -decarboxylase activity of immobilized Pseudomonas dacunhae cells, alanine racemase and fumarase activities should be eliminated. We investigated various procedures to eliminate these side reactions, and found that both activities of intact E. coli cells could be eliminated by treating the culture broth at pH 5.0 and 45° C for 1 h, and those of intact P. dacunhae cells could be eliminated by treating the culture broth at pH 4.75 and 30° C for 1 h. Further, it was confirmed that l-alanine was efficiently produced using these two immobilized pH-treated microorganisms.     

Continuous production of l-aspartic acid from ammonium fumarate using immobilized cells by capture on the surface of nonwoven cloth coated with a pyridinium-type polymer

Cells of Escherichia coli possessing aspartase activity were immobilized by capture on the surface of nonwoven cloth coated with 10 mg/g of poly (N-benzyl-4-vinylpyridinium chloride-co-styrene), a pyridinium-type polymer. Continuous operation of a fixed-bed column reactor containing 21.7 g/l of the immobilized cells produced l-aspartic acid in 95% yield from ammonium fumarate in the case where influent solution contained 0.1 mol/l of the fumarate and space velocity was 1.36 h⁻¹ at 30°C and pH 8.9. Immobilization on the coated nonwoven cloth insignificantly affected optimal pH of the biochemical reaction. Stability of enzymic activity of the immobilized cells was much improved by use of the coated nonwoven cloth as the supporting material instead of beads of insoluble pyridinium-type resin. l-Aspartic acid was obtained in 77% yield after 160 d of continuous operation, and the initial yield was estimated to require about 500 d for halving.     

Adsorption of IgG onto hydrophobic teflon. Differences between the F(ab) and F(c) domains

The effect of differences in the degree of hydrophobicity of protein patches/fragments on the adsorption behaviour of the protein is investigated. The adsorption isotherm of a monoclonal mouse anti-human immunoglobulin G (isotype 2b) onto hydrophobic Teflon particles is measured using a depletion method. The adsorption-induced denaturation of the immunoglobulin as a function of the adsorbed amount is studied by differential scanning calorimetry, and the corresponding rearrangements in the secondary structure of the whole IgG molecule and its F(ab) and F(c) fragments are determined by circular dichroism spectroscopy. The effects of adsorption on the F(ab) and F(c) fragments in the intact IgG molecule occur independently. Adsorption of the whole IgG molecule leads to denaturation of the F(ab) fragments, whereas the F(c) fragment remains unperturbed; adsorption of the isolated fragments results in structural changes in both F(ab) and F(c). The surface hydrophobicity of the isolated fragments was studied by HPLC. These experiments support the hypothesis that differences in the degree of denaturation between F(ab) and F(c) are due to the higher degree of hydrophobicity of the F(ab) fragment. The adsorption-induced changes in the secondary structure are more prominent for the isolated fragments as compared to intact IgG. This is ascribed to the higher flexibility of the isolated fragment, as compared to the fragment in the whole molecule.     

Novel carbamate-linked quaternary ammonium lipids containing unsaturated hydrophobic chains for gene delivery

In this paper, two novel carbamate-linked quaternary ammonium lipids (MU18: a lipid with a mono-ammonium head; GU18: a lipid with a Gemini-ammonium head) containing unsaturated hydrophobic chains were designed and synthesized. The chemical structures of the synthetic lipids were characterized by infrared spectrum, ESI-MS, ¹H NMR, ¹³C NMR, and HPLC. For investigating the effect of unsaturation on gene delivery, the previous reported saturated cationic liposomes (MS18 and GS18) were used as comparison. Cationic liposomes were prepared by using these cationic lipids and neutral lipid DOPE at the molar ratio of 1:1. Particle sizes and zeta potentials of the cationic liposomes were studied to show that they were suitable for gene transfection. The binding abilities of the cationic liposomes were investigated by gel electrophoresis at various N/P ratios from 0.5/1 to 8/1. The results indicated that the binding ability of GU18 was much better than MU18 and the saturated cationic liposomes (MS18 and GS18). DNA transfection of these liposomes comparable to commercially available reagent (DOTAP) was achieved in vitro against Hela, HepG-2 and NCI-H460 cell lines. GU18 showed higher transfection at the N/P ratio of 3/1 than other cationic liposomes and the positive control, DOTAP. All of the liposomes presented a relatively low cytotoxicity, which was measured by MTT. Therefore, the synthetic lipids bearing unsaturated hydrophobic chains and Gemini-head could be promising candidates for gene delivery.     

Rapid desalting of ammonium sulfate solutions by hydrophobic interaction chromatography

Open-air hydrophobic interaction chromatography with alkyl carbon functional groups coupled to agarose beads has been used to desalt large volumes of ammonium sulfate-fractionated bacterial cell lysates. The protein of interest can be simultaneously desalted and concentrated in less than 4 h, and the yield is significantly better than that obtained by the standard technique of precipitation, centrifugation, and dialysis.     

Thermodynamics of the conversion of fumarate to L-(-)-malate

The thermodynamics of the conversion of aqueous fumarate to L-(-)-malate has been investigated using both heat conduction microcalorimetry and a gas chromatographic method for determining equilibrium constants. The reaction was carried out in aqueous Tris-HCl buffer over the pH range 6.3-8.0, the temperature range 25-47 degrees C, and at ionic strengths varying from 0.0005 to 0.62 mol kg-1. Measured enthalpies and equilibrium ratios have been adjusted to zero ionic strength and corrected for ionization effects to obtain the following standard state values for the conversion of aqueous fumarate 2- to malate 2- at 25 degrees C: K = 4.20 +/- 0.05, delta G degrees = -3557 +/- 30 J mol-1, delta H degrees = -15670 +/- 150 J mol-1, and delta C degrees p = -36 +/- J mol-1 K-1. Equations are given which allow one to calculate the combined effects of pH and temperature on equilibrium constants and enthalpies of this reaction.     

Adsorption properties of gold onto a chitosan derivative

In order to find a material which can be used for the recovery of Au(III), a chitosan derivative was synthesized by carboxymethylation and grafting sulfur groups onto cross-linked chitosan backbone. Adsorption studies were carried out at different pH values to optimize the pH condition. Batch method was conducted to study the effects of parameters such as reaction time, initial metal concentration and temperature on Au(III) sorption. The maximum adsorption affinity for Au(III) was found to be 8.32mmol/g at pH 4.0, 25°C. The results of kinetic study showed that the adsorption reaction followed the pseudo second order model. The derivative showed high adsorption ability and reusability toward Au(III). All results suggested that the chitosan derivative had potential to be utilized in the recovery of Au(III) from aqueous medium.     

Adsorption of heavy metals onto sewage sludge-derived materials

Two materials were produced from sewage sludge by: (1) pyrolysis of dried sewage sludge (PS); (2) chemical activation of dried sewage sludge with ZnCl(2) followed by pyrolysis (AS). The aim was to study the application of these materials for metal purification from water and to determine the efficiency of each material. Although AS displayed higher capacity, both PS and AS were able to adsorb these metals and the preferential order was equal: Hg(II)>Pb(II)>Cu(II)>Cr(III). For each metal-adsorbent pair, metal adsorption was highly pH dependent. In all cases the equilibrium was well described both by the Langmuir and the Freundlich isotherms. At the corresponding optimum pH, AS showed the following adsorption capacities: 175.4, 64.1, 30.7 and 15.4 mg/g of Hg(II), Pb(II), Cu(II) and Cr(III), respectively. These results indicate the potential application of these sewage sludge based adsorbents for the treatment of metal polluted effluents.     

Adsorption of Hemoglobin and Casein onto Air Bubbles

Effects of pH, sodium chloride, temperature, and particle size were studied on the adsorption of proteins onto air bubbles. The results suggested that the froth flotation could be applied to the recovery of dissolved proteins with a comparable efficiency to the active sludge method. Such a strategy was proposed as to strip the dissolved hemoglobin under alkaline conditions or in the presence of sodium chloride, and to concentrate it under acidic conditions. Temperature was of little effect. Flotation of the precipitated proteins was much more efficient than that of the dissolved proteins. Particle size greatly affected the efficiency of flotation of the precipitated proteins.     

Adsorption of Vibrio parahaemolyticus onto Chitin and Copepods

Vibrio parahaemolyticus was observed to adsorb onto chitin particles and copepods. The efficiency of adsorption was found to be dependent on pH and on the concentration of NaC1 and other ions found in seawater. Highest efficiency was observed in water samples collected from Chesapeake Bay and lowest in water from the open sea. V. parahaemolyticus was found to adborb onto chitin with the highest efficiency of the several bacterial strains tested. Escherichia coli and Pseudomonas fluorescens did not adsorb onto chitin. The adsorption effect is considered to be one of the major factors determining the distribution of this species and affecting the annual cycle of V. parahaemolyticus in the estuarine system.     

Macroporous hydrophobic cloth (polymacron) as a solid phase for nucleic acid probe hybridizations

Polyester cloth (polymacron) was employed as a solid phase onto which polymerase chain reaction (PCR) products from theListeria monocytogenes hlyA gene were dot blotted and sensitively detected by hybridization with nucleic acid probes. This inexpensive solid phase exhibited a high DNA binding capacity and provided ease of handling and washing between each reaction step, resulting in simple hybridization procedures for PCR product detection.Contribution No. 95-004     

Adsorption of Saccharomyces cerevisiae onto cellulose and ECTEOLA-cellulose films for ethanol production

Epichlorohydrin-triethanolamine (ECTEOLA)-cellulose films (paper and cloth) have been found to bind Saccharomyces cerevisiae cells which were able to develop metabolically active colonies on the surface of the films. Unmodified cellulose films also bound the yeast but to a lesser extent. Film fermenters were constructed by coiling a double layer of the cloth and copper screen and vertically placing the resulting cartridge into a column. These film fermenters were able to convert the sugars (14%) in the hydrolysate of a Jerusalem artichoke tuber into ethanol, with 90% of the theoretical yield after 6 h of fermentation. The bound yeast produced ethanol at a specific rate of 1.0 g ethanol per g cell per hour.