@article {1484, title = {Molecular structure of fd (f1, M13) filamentous bacteriophage refined with respect to X-ray fibre diffraction and solid-state NMR data supports specific models of phage assembly at the bacterial membrane}, journal = {Journal of Molecular Biology}, volume = {355}, number = {2}, year = {2006}, note = {ISI Document Delivery No.: 999EPTimes Cited: 30Cited Reference Count: 84}, month = {Jan}, pages = {294-309}, type = {Article}, abstract = {Filamentous bacteriophage (Inovirus) is a simple and well-characterized model system. The phage particle, or virion, is about 60 A in diameter and several thousand angstrom units long. The virions are assembled at the bacterial membrane as they extrude out of the host without killing it, an example of specific transport of nucleoprotein assemblages across membranes. The Ff group (fd, f1. and M13) has been especially widely studied. Models of virion assembly have been proposed based on a molecular model of the fd virion derived by X-ray fibre diffraction. A somewhat different model of the fd virion using solid-state NMR data has been proposed, not consistent with these models of assembly nor with the X-ray diffraction data. Here we show that reinterpreted NMR data are also consistent with the model derived from X-ray fibre diffraction studies, and discuss models of virion assembly. (c) 2005 Elsevier Ltd. All rights reserved.}, keywords = {ALPHA-HELICES, ALPHA-HELIX, ATOMIC REFINEMENT, fibre diffraction, filamentous bacteriophage, INOVIRUS, MAJOR COAT PROTEIN, MEMBRANE, ORIENTATIONAL RESTRAINTS, PF1 BACTERIOPHAGE, PISEMA, PROTEINS, RESOLUTION, SINGLE-STRANDED-DNA, VIRION, VIRUS}, isbn = {0022-2836}, url = {://000234371900012}, author = {Marvin, D. A. and Welsh, L. C. and Symmons, M. F. and Scott, W. R. P. and Straus, S. K.} } @article {1163, title = {First passage times of driven DNA hairpin unzipping}, journal = {Physical Biology}, volume = {2}, number = {3}, year = {2005}, note = {ISI Document Delivery No.: 007TLTimes Cited: 11Cited Reference Count: 25}, month = {Sep}, pages = {166-174}, type = {Article}, abstract = {We model the dynamics of voltage-driven transport of DNA hairpins through transmembrane channels. A two-dimensional stochastic model of the DNA translocation process is fit to the measurements of Mathe, who pulled self-hybridized DNA hairpins through lipid-embedded alpha-hemolysin channels. As the channel was too narrow to accommodate hybridized DNA, dehybridization of the hairpin became the rate-limiting step of the transport process. We show that the mean first passage time versus voltage curve for the escape of the DNA from the transmembrane channel can be divided into two regions: (1) a low-voltage region where the DNA slides out of the pore in reverse and without undergoing significant dehybridization, and (2) a region where the DNA dehybridizes under the influence of the applied voltage and translocates across the membrane.}, keywords = {CHANNEL, DYNAMICS, FORCE, MEMBRANE, MOLECULES, NANOPORE, POLYMER TRANSLOCATION, PORE, SEQUENCE}, isbn = {1478-3967}, url = {://000234992600006}, author = {Lakatos, G. and Chou, T. and Bergersen, B. and Patey, G. N.} } @article {942, title = {Continuous electrophoretic purification of individual analytes from multicomponent mixtures}, journal = {Analytical Chemistry}, volume = {76}, number = {8}, year = {2004}, note = {ISI Document Delivery No.: 816FWTimes Cited: 10Cited Reference Count: 36}, month = {Apr}, pages = {2298-2305}, type = {Article}, abstract = {Individual analytes can be isolated from multicomponent mixtures and collected in the outlet vial by carrying out electrophoretic purification through a capillary column. Desired analytes are allowed to migrate continuously through the column under the electric field while undesired analytes are confined to the inlet vial by application of a hydrodynamic counter pressure. Using pressure ramping and buffer replenishment techniques, 18\% of the total amount present in a bulk sample can be purified when the resolution to the adjacent peak is similar to3. With a higher resolution, the yield could be further improved. Additionally, by periodically introducing fresh buffer into the sample, changes in pH and conductivity can be mediated, allowing higher purity (99.5\%) to be preserved in the collected fractions. With an additional reversed cycle of flow counterbalanced capillary electrophoresis, any individual component in a sample mixture can be purified providing it can be separated in an electrophoresis system.}, keywords = {CAPILLARY-ZONE-ELECTROPHORESIS, CHIRAL SEPARATIONS, CHROMATOGRAPHY, ENANTIOMERS, FRACTION COLLECTOR, FREE-FLOW ELECTROPHORESIS, ISOELECTRIC-FOCUSING SEPARATION, MASS-SPECTROMETRY, MEMBRANE, PREPARATIVE-SCALE}, isbn = {0003-2700}, url = {://000221096800019}, author = {McLaren, D. G. and Chen, D. D. Y.} } @article {687, title = {A quantitative study of continuous flow-counterbalanced capillary electrophoresis for sample purification}, journal = {Electrophoresis}, volume = {24}, number = {17}, year = {2003}, note = {ISI Document Delivery No.: 723ZZTimes Cited: 10Cited Reference Count: 25}, month = {Sep}, pages = {2887-2895}, type = {Article}, abstract = {A systematic evaluation of continuous flow-counterbalanced capillary electrophoresis for microscale preparative applications is presented. The success of the technique was found to depend on the specific nature of the analyte and background electrolyte and was most heavily influenced by factors such as solution conductivity and rate of buffer depletion. The performance of the technique for the system studied was ultimately limited by contamination arising from changes in analyte mobilities during extended run times. Marked improvements in both purification rate and yield were observed using the zwitterionic buffer 2-(N-cyclohexylamino)ethanesulfonic acid when compared to similar runs carried out using a borate background electrolyte. A quantitative evaluation of the technique was performed for the analytes studied and the performance of the technique has been compared to fraction collection methods. The highest recovery achieved was 5.2\% of the fastest migrating component present in the original sample with a resolution of 9 to the adjacent peak and required 100 min under optimized conditions. Recovery could be further increased to 9.0\% in 120 min for the same analyte using pressure-ramped flow-counterbalanced capillary electrophoresis.}, keywords = {amino acid, BUFFER, DESIGN, flow-counterbalanced capillary electrophoresis, FRACTION COLLECTOR, LASER-INDUCED FLUORESCENCE, MASS-SPECTROMETRY, MEMBRANE, MICELLAR ELECTROKINETIC CHROMATOGRAPHY, PLASMA, PURIFICATION, SAMPLE, SEPARATION, tetramethylrhodamine isothiocyanate, ZONE-ELECTROPHORESIS, zwitterionic buffer}, isbn = {0173-0835}, url = {://000185462800002}, author = {McLaren, D. G. and Chen, D. D. Y.} } @article {3061, title = {BINDING AND TRANSPORT OF CALCIUM-IONS BY SYNTHETIC ANALOGS OF IONOMYCIN}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {72}, number = {6}, year = {1994}, note = {ISI Document Delivery No.: NV309Times Cited: 4Cited Reference Count: 66}, month = {Jun}, pages = {1512-1524}, type = {Article}, abstract = {The transport of calcium ions across an organic barrier by a series of synthetic analogues of ionomycin was measured in a cylindrical glass cell using chloroform as the artificial membrane. The presence of a beta-diketone and carboxyl group in the same molecule and a sufficient Lipid solubility of the compounds were shown to be necessary and sufficient conditions for Ca2+ transport. Small and no transport of Ca2+ were found for analogues 5 and 6, respectively, due to the low lipid solubility of these compounds. The Ca2+ transport rate for analogues 8 and 13-15 followed the order of 8 > 13 > 14 > 15, which demonstrated that optimal Ca2+ transport was achieved when the beta-diketone was separated from the carboxyl group by seven methylene units, identical to that found in ionomycin. Analogues 8-10 were comparable to ionomycin and calcimycin in terms of Ca2+ transport. Ca2+ transport by the analogues was found to be a saturable process that obeyed Michaelis-Menten kinetics. It was dependent on the pH in the aqueous source phase and independent of the pH in the receiving phase. Both the carboxyl and the beta-diketo groups were ionized in the transport of Ca2+, indicating that the stoichiometry of Ca2+ complex in transport was 1:1. The pK(a) of the beta-diketone of the analogues was determined to be in the range of 10.90-11.16 in 80\% MeOH-H2O. The pK(a) values were related to the lipid solubility of the compounds and the hydrocarbon chain length between the beta-diketone and the carboxyl group. The binding constants of the analogues with Ca2+ and Mg2+ in 80\% MeOH-H2O were determined to be in the order of 10(2) M(-1) and 10(3) M(-1), respectively, using the pK(a) method. The stoichiometry of Mg2+ binding was found to be 1:1 by the mole ratio method. The selectivity in binding and in transport followed the same order, being Mg2+ > Ca2+ >> Na+, K+.}, keywords = {A23187, ACETYLACETONE, ALKALINE-EARTH CATIONS, COMPLEXATION, COUNTERTRANSPORT, COUPLED, DIVALENT-CATION IONOPHORE, FORMATION-CONSTANTS, MEMBRANE, METAL-IONS, SYSTEMS}, isbn = {0008-4042}, url = {://A1994NV30900011}, author = {Hu, Thomas Q. and Weiler, L.} } @article {7204, title = {THE USE OF LIPOSOMES IN PREDICTING THE BIOLOGICAL MOBILITY OF ARSENIC COMPOUNDS}, journal = {Applied Organometallic Chemistry}, volume = {6}, number = {2}, year = {1992}, note = {ISI Document Delivery No.: HQ168Times Cited: 10Cited Reference Count: 14INTERNATIONAL CONF ON ENVIRONMENTAL AND BIOLOGICAL ASPECTS OF MAIN-GROUP ORGANOMETALS ( ICEBAMO )SEP 15-19, 1991PADUA, ITALYUNIV PADUA, ITALIAN CHEM SOC}, month = {Apr}, pages = {179-183}, type = {Proceedings Paper}, abstract = {Efflux studies of radio-labelled methylarsonic acid (MMA) and dimethylarsinic acid (DMA) encapsulated in liposomes afford the following permeability values for the two arsenicals: 1.4 x 10(-13) cm s-1 and 4.5 x 10(-11) cm s-1 for MMA and DMA, respectively. These data are compared with the octanol/water partition coefficients which are 7.4 x 10(-3) and 8.4 x 10(-3) for MMA and DMA, respectively.}, keywords = {DIFFUSION, LIPOSOMES, MEMBRANE, ORGANOARSENIC}, isbn = {0268-2605}, url = {://A1992HQ16800010}, author = {Cullen, W. R. and Nelson, J.} }