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Continuous free-flow electrophoresis separation
RESEARCH TRENDS Graft co-polymerization of polyurethane membranes To improve water wettability of polyurethane (PU), graft copolymerization with acrylic acid (AA) and crotonic acid (CA) was performed using a benzoyl peroxide (BO) initiator. The grafting ~eaction was carried out by placing the membranes in aqueous solutions of AA and CA at constant temperatures. Variations of graft yield with time, temperature, initiator and monomer concentrations were investigated. The optimum temperature, polymer; ization time, monomer and initiator concentrations for AA were found to be 70°C, 3 h, 1.5M and 5.0 x 10-2M, while for CA these figures were 70°C, 1 h, 1.5M and 4.0 × 10-2M, respectively. The grafting membranes were characterized by FTIR spectroscopy and scanning electron microscopy analysis, and the effect of grafting on the equilibrium water content (EWC) of PU membranes was obtained by swelling measurements. M. Pulat, D. Babayiit: J. of Applied Polymer Science 80(14) 2690-2695 (28 June 2001).
Hydrogen ion-selective solid-state electrode A hydrogen ion-selective solidcontact electrode, based on tribenzylamine, has shown the best Nernstian slope, selectivity and the widest response range in Trisbuffered pH sample solutions. Their linear dynamic range was pH 2.48-11.21 and Nernstian slope showed 55.1 mV/pH (at 20±0.2°C). When it was directly applied to human whole blood (in pH range 6.0-8.5), the research workers could get the same results. This electrode continuously contacted Tris 7.47 buffered solutions, human whole blood and hydrofluoric acid solutions for one month without any loss of performance. In particular, hydrofluoric acid did not influence the surface of the electrode, thus it was maintained without showing any changes in potentials after being used in hydrofluoric acid solution. The standard deviation in the EMF differences determined was 1.0 mV (N = 10) at Tris buffer solution of pH 6.5, and 0.5 mV at Tris buffer solution of pH 8.5. The 90% response time of the electrodes obtained by injection of
@-
hydrochloric acid into the Tris buffer sample solution was less than 8 s. W.-S. Han, M.-Y. Park, K.-C. Chung, D.-H. Cho, T.-K. Hong: Electroanalysis 13(11) 955-959 (July 2001).
Continuous free-flow electrophoresis separation The conventional approach for analysing the protein complement of a genome involves the combination of two-dimensional gel electrophoresis (2-DE) and massspectrometric-based protein identification technologies. While 2-DE is a powerful separation technique, it is severely limited by the insolubility of certain classes of proteins (for example, hydrophobic membrane proteins), as well as the amount of protein that can be processed. Here, the authors describe a simple procedure for resolving complex mixtures of proteins that involves a combination of flee-flow electrophoresis (FFE), a liquid-based isoelectric focusing (IEF) method, and sodium dodecylsulfatepolyacrylamide gel electrophoresis (SDS-PAGE), Resolved proteins were identified by peptide fragment sequencing using capillary column reversed-phase high-performance liquid chromatography (RPHPLC)/mass spectrometry (MS). An initial demonstration of the method was performed using digitonin/ethylenediaminetetraacetic acid (EDTA) extracted cytosolic proteins from the human colon carcinoma cell line, LIM 1215. Cy$osolicproteins were separated by liquid-based IEF (pH range 3-10) into 96 fractions, and each FFE fraction was further fractionated by SDS-PAGE. Selected protein bands were excised from the SDS-PAGE gel, digested in situ with trypsin, and subsequently identified by on-line RP-HPLC/electrospray-ionization ion trap MS. The results indicate that FFE is an extremely powerful liquid-based IEF method for resolving proteins; it is not limited by the amount of sample that can be loaded onto the instrument; and it is capable of flactionating intact protein complexes (a potentially powerful tool for cell-mapping proteomics). An upto-date list of cytosolic proteins from the human colorectal carcinoma cell line LIM 1215 can be found in the Joint Protein Structure Laboratory (JPSL) proteome
database. This information will provide an invaluable resource for future proteomics-based biological studies of colon cancer..The JPSL proteome database can be found at http://www, ludwig.edu.au/ jpsl/jpslhome.html. P. Hoffmann, H. Ji, R.L. Moritz, L.M. Connolly, D.E Frecklington, M.J. Layton, J.S. Eddes, R.J. Simpson: Proteomics1(7) 807 (July 2001).
Modified polysulfones The authors of this research previously conducted a detailed study of gas-transport and other properties of a series of silicon derivatives of Udel polysulfone (PSf) and Radel polyphenylsulfone. The present research work details their preparation by the reaction of lithiated polymer intermediates with chlorosilylalkylaryl electrophiles. Ortho-sulfone-substituted polymers with pendant trimethylsilyl, dimethylphenylsilyl and diphenylmethylsilyl and other groups were obtained by direct metalation followed by the reaction of the dilithiated intermediate with the appropriate silyl electrophile. In addition, the structural regularity and geometry of the dilithiated site was also exploited to introduce silicon into the main chain by the reaction of dichlorosilyl electrophiles, leading to the formation of a new tricyclic heteroatom ring. Ortho-ether PSf derivatives were obtained from a dibrominated polymer via the lithiation of brominated polymer and reaction with a silyl electrophile. The degree of substitution of the silyl groups was 2.0 or less from dilithiated polymers, and was dependent on the electrophile reactivity and reaction conditions. A detailed structural characterization of the polymers by NMR and IR spectroscopy is reported in addition to glass-transition temperatures and thermal stabilities. M.D. Guiver, G.E Robertson, S. Rowe, S. Foley, Y.S. Kang, H.C. Park, J. Won, H. Nam Le Thi: J. o f
Polymer Science Part A: Polymer Chemistry 39(13) 2103-2124 (1 July 2001).
Fractionation of biological macromoleculesusing carrier phase ultrafiltration This article discusses a novel mode of operation for ultrafiltration
processes termed 'carrier phase ultrafiltration' (CPUF). CPUF is based on a modification of dead-end ultraflltration. Macromolecular flactionation using ultrafiltration is known to be strongly influenced by operating and physicochemical parameters, and requires precise fine-tuning. CPUF facilitates the flactionation of high-value biological macromolecules at optimized conditions, and has several advantages over conventional ultrafiltration modes. The present work discusses the flactionation of two model proteins, lysozyme (MW 14100) and myoglobin (MW 17 000), by CPUF using a 25 kDa MWCO polysulfone membrane. Fractionation was carried out using two different CPUF modes - - pulse input CPUF, and step input CPUE A high recovery of pure product was obtained in each case. These results are compared with those obtained from conventional ultrafiltration experiments. R. Ghosh: Biotechnology & Bioengineering74(1) 1-11 (5 July 2001).
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MembraneTechnologyNo. 137
Hydrogen ion-selective solid-state electrode A hydrogen ion-selective solidcontact electrode, based on tribenzylamine, has shown the best Nernstian slope, selectivity and the widest response range in Trisbuffered pH sample solutions. Their linear dynamic range was pH 2.48-11.21 and Nernstian slope showed 55.1 mV/pH (at 20±0.2°C). When it was directly applied to human whole blood (in pH range 6.0-8.5), the research workers could get the same results. This electrode continuously contacted Tris 7.47 buffered solutions, human whole blood and hydrofluoric acid solutions for one month without any loss of performance. In particular, hydrofluoric acid did not influence the surface of the electrode, thus it was maintained without showing any changes in potentials after being used in hydrofluoric acid solution. The standard deviation in the EMF differences determined was 1.0 mV (N = 10) at Tris buffer solution of pH 6.5, and 0.5 mV at Tris buffer solution of pH 8.5. The 90% response time of the electrodes obtained by injection of
@-
hydrochloric acid into the Tris buffer sample solution was less than 8 s. W.-S. Han, M.-Y. Park, K.-C. Chung, D.-H. Cho, T.-K. Hong: Electroanalysis 13(11) 955-959 (July 2001).
Continuous free-flow electrophoresis separation The conventional approach for analysing the protein complement of a genome involves the combination of two-dimensional gel electrophoresis (2-DE) and massspectrometric-based protein identification technologies. While 2-DE is a powerful separation technique, it is severely limited by the insolubility of certain classes of proteins (for example, hydrophobic membrane proteins), as well as the amount of protein that can be processed. Here, the authors describe a simple procedure for resolving complex mixtures of proteins that involves a combination of flee-flow electrophoresis (FFE), a liquid-based isoelectric focusing (IEF) method, and sodium dodecylsulfatepolyacrylamide gel electrophoresis (SDS-PAGE), Resolved proteins were identified by peptide fragment sequencing using capillary column reversed-phase high-performance liquid chromatography (RPHPLC)/mass spectrometry (MS). An initial demonstration of the method was performed using digitonin/ethylenediaminetetraacetic acid (EDTA) extracted cytosolic proteins from the human colon carcinoma cell line, LIM 1215. Cy$osolicproteins were separated by liquid-based IEF (pH range 3-10) into 96 fractions, and each FFE fraction was further fractionated by SDS-PAGE. Selected protein bands were excised from the SDS-PAGE gel, digested in situ with trypsin, and subsequently identified by on-line RP-HPLC/electrospray-ionization ion trap MS. The results indicate that FFE is an extremely powerful liquid-based IEF method for resolving proteins; it is not limited by the amount of sample that can be loaded onto the instrument; and it is capable of flactionating intact protein complexes (a potentially powerful tool for cell-mapping proteomics). An upto-date list of cytosolic proteins from the human colorectal carcinoma cell line LIM 1215 can be found in the Joint Protein Structure Laboratory (JPSL) proteome
database. This information will provide an invaluable resource for future proteomics-based biological studies of colon cancer..The JPSL proteome database can be found at http://www, ludwig.edu.au/ jpsl/jpslhome.html. P. Hoffmann, H. Ji, R.L. Moritz, L.M. Connolly, D.E Frecklington, M.J. Layton, J.S. Eddes, R.J. Simpson: Proteomics1(7) 807 (July 2001).
Modified polysulfones The authors of this research previously conducted a detailed study of gas-transport and other properties of a series of silicon derivatives of Udel polysulfone (PSf) and Radel polyphenylsulfone. The present research work details their preparation by the reaction of lithiated polymer intermediates with chlorosilylalkylaryl electrophiles. Ortho-sulfone-substituted polymers with pendant trimethylsilyl, dimethylphenylsilyl and diphenylmethylsilyl and other groups were obtained by direct metalation followed by the reaction of the dilithiated intermediate with the appropriate silyl electrophile. In addition, the structural regularity and geometry of the dilithiated site was also exploited to introduce silicon into the main chain by the reaction of dichlorosilyl electrophiles, leading to the formation of a new tricyclic heteroatom ring. Ortho-ether PSf derivatives were obtained from a dibrominated polymer via the lithiation of brominated polymer and reaction with a silyl electrophile. The degree of substitution of the silyl groups was 2.0 or less from dilithiated polymers, and was dependent on the electrophile reactivity and reaction conditions. A detailed structural characterization of the polymers by NMR and IR spectroscopy is reported in addition to glass-transition temperatures and thermal stabilities. M.D. Guiver, G.E Robertson, S. Rowe, S. Foley, Y.S. Kang, H.C. Park, J. Won, H. Nam Le Thi: J. o f
Polymer Science Part A: Polymer Chemistry 39(13) 2103-2124 (1 July 2001).
Fractionation of biological macromoleculesusing carrier phase ultrafiltration This article discusses a novel mode of operation for ultrafiltration
processes termed 'carrier phase ultrafiltration' (CPUF). CPUF is based on a modification of dead-end ultraflltration. Macromolecular flactionation using ultrafiltration is known to be strongly influenced by operating and physicochemical parameters, and requires precise fine-tuning. CPUF facilitates the flactionation of high-value biological macromolecules at optimized conditions, and has several advantages over conventional ultrafiltration modes. The present work discusses the flactionation of two model proteins, lysozyme (MW 14100) and myoglobin (MW 17 000), by CPUF using a 25 kDa MWCO polysulfone membrane. Fractionation was carried out using two different CPUF modes - - pulse input CPUF, and step input CPUE A high recovery of pure product was obtained in each case. These results are compared with those obtained from conventional ultrafiltration experiments. R. Ghosh: Biotechnology & Bioengineering74(1) 1-11 (5 July 2001).
II echn ogy Next
month News
Businessactivities Industrytrends Commercial news New products
Features Developmentsand applications around the world
Research Trends The latest membrane research published in the key journals
Patents Recentlypublished US and WO patents
Events Calendar Conferencesand showsrelevant to the membranes industry
MembraneTechnologyNo. 137