Determination of electroosmotic and electrophoretic mobility of DNA and dyes in low ionic strength solutions

2017 ◽  
Vol 39 (5-6) ◽  
pp. 862-868 ◽  
Author(s):  
Joshua Lallman ◽  
Rachel Flaugh ◽  
Kristy L. Kounovsky-Shafer
Keyword(s):  
Ionic Strength ◽  
Electrophoretic Mobility ◽  
Low Ionic Strength

scholarly journals Comparison of mammalian mitochondrial ribosomal ribonucleic acid from different species

1972 ◽  
Vol 128 (5) ◽  
pp. 1033-1041 ◽  
Author(s):  
R. S. Mitra ◽  
B. Bartoov ◽  
J. Monahan ◽  
K. B. Freeman
Keyword(s):  
Ionic Strength ◽  
Electrophoretic Mobility ◽  
Density Gradients ◽  
Molecular Weights ◽  
Mitochondrial Rrna ◽  
Electrophoretic Mobilities ◽  
Ribosomal Ribonucleic Acid ◽  
Rrna Species ◽  
Low Ionic Strength ◽  
Human And Mouse

Mitochondrial ribosomal RNA species from mouse L cells, rat liver, rat hepatoma, hamster BHK-21 cells and human KB cells were examined by electrophoresis on polyacrylamide–agarose gels and sedimentation in sucrose density gradients. The SE (electrophoretic mobility) and S values of mitochondrial rRNA of all species were highly dependent on temperature and ionic strength of the medium; the SE values increased and the S values decreased with an increase in temperature at a low ionic strength. At an ionic strength of 0.3 at 23–25°C or an ionic strength of 0.01 at 3–4°C the S and SE values were almost the same being about 16.2–18.0 and 12.3–13.6 for human and mouse mitochondrial rRNA. The molecular weights under these conditions were calculated to be 3.8×105–4.3×105 and 5.9×105–6.8×105, depending on the technique used. At 25°C in buffers of low ionic strength mouse mitochondrial rRNA species had a lower electrophoretic mobility than those of human and hamster. Under these conditions the smaller mitochondrial rRNA species of hamster had a lower electrophoretic mobility than that of human but the larger component had an identical mobility. Mouse and rat mitochondrial rRNA species had identical electrophoretic mobilities. Complex differences between human and mouse mitochondrial rRNA species were observed on sedimentation in sucrose density gradients under various conditions of temperature and ionic strength. Mouse L-cell mitochondrial rRNA was eluted after cytoplasmic rRNA on a column of methylated albumin–kieselguhr.

scholarly journals Use of an ion-selective electrode for free copper measurements in low salinity and low ionic strength matrices

2007 ◽  
Vol 4 (2) ◽  
pp. 90 ◽  
Author(s):  
Julien Rachou ◽  
Christian Gagnon ◽  
Sébastien Sauvé
Keyword(s):  
Ionic Strength ◽  
Ion Selective Electrode ◽  
Metal Species ◽  
Analytical Determination ◽  
Operational Parameters ◽  
Selective Electrode ◽  
Time Saving ◽  
Low Salinity ◽  
Low Ionic Strength

Environmental context. The toxicity of metals in the environment is controlled by several parameters including total metal concentration, pH and organic and inorganic ligands (type and concentration). The characterisation of different metal pools in natural matrices (e.g. seawater, soil) is important for the evaluation of their toxic impact. The copper ion-selective electrode (Cu-ISE) is a method of choice for the analytical determination of the speciation (i.e. chemical forms) of divalent copper in natural matrices. This paper clarifies several operational parameters in the hope of decreasing variability of results and increasing the application domain of the Cu-ISE. Abstract. The determination of free copper concentrations in natural matrices is critical for the evaluation of copper toxicity. The ISE is one of the few analytical means for determining the direct speciation of free metal species. We have refined the method for low salinity and low ionic strength solutions for application with soil water extracts or fresh waters. Moreover, we have detailed and standardised a method for using a Cu-ISE with an autotitrator. The standardisation shows a good response and allows significant time saving (under 2 h for the calibration). The results obtained using the ISE are compared with those predicted in the presence of different organic ligands or even the lower free Cu2+ activities resulting from the formation of Cu hydroxyl species. The method was validated for the determination of Cu speciation at environmentally relevant free Cu2+ activity, i.e. ranging between 10−14 to 10−4 M. The chemical equilibrium calculations were made using the MINEQL+ software and the results agree well for pH values between 3 and 10. In terms of precision, the standard deviations of the measured values never exceed 0.1 units, and in terms of accuracy, the measured values were very close to the nominal values, within a range of 0.1. Outside the optimal pH range, the electrode yields higher activity than expected.

scholarly journals Determination of free metal ion concentrations with AGNES in low ionic strength media

2013 ◽  
Vol 689 ◽  
pp. 276-283 ◽  
Author(s):  
D. Aguilar ◽  
C. Parat ◽  
J. Galceran ◽  
E. Companys ◽  
J. Puy ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Metal Ion ◽  
Ion Concentrations ◽  
Low Ionic Strength ◽  
Free Metal ◽  
Free Metal Ion

Recommendations for the determination of pH in low ionic strength fresh waters

1985 ◽  
Vol 57 (6) ◽  
pp. 877-886 ◽  
Author(s):  
A. K. Covington ◽  
P. D. Whalley ◽  
William Davison
Keyword(s):  
Ionic Strength ◽  
Fresh Waters ◽  
Low Ionic Strength

Determination of Trace Metals in Low Ionic Strength Waters Using Zeeman and Deuterium Background Correction for Graphite Furnace Atomic Absorption Spectrometry

1986 ◽  
Vol 69 (4) ◽  
pp. 704-708
Author(s):  
Marvin J Fishman ◽  
Gary R Perryman ◽  
LeRoy J Schroder ◽  
Edward W Matthews
Keyword(s):  
Ionic Strength ◽  
Graphite Furnace ◽  
Absorption Spectrometry ◽  
Sample Volume ◽  
Background Correction ◽  
Analytical Wavelength ◽  
Graphite Furnace Atomic Absorption ◽  
Low Ionic Strength ◽  
Copper Lead

Abstract Each U.S. Geological Survey water quality laboratory evaluated one of 2 background correction techniques: Zeeman and deuterium. A L’vov-type platform was used to determine cadmium, chromium, cobalt, copper, lead, manganese, nickel, and zinc in low ionic strength waters, submitted as blind samples. Matrix modifers were used to determine cadmium, chromium, lead, manganese, and zinc. Results were comparable for all metals, except cadmium and nickel, at the μg/L range. Analytical ranges for a 20 μL sample volume are presented. Detection limits can be changed by varying the volume of sample injected, by using multiple injections, or by changing the analytical wavelength.

scholarly journals Quantitative determination of the binding of β2-glycoprotein I and prothrombin to phosphatidylserine-exposing blood platelets

2005 ◽  
Vol 386 (2) ◽  
pp. 271-279 ◽  
Author(s):  
Edouard M. BEVERS ◽  
Marie P. JANSSEN ◽  
Paul COMFURIUS ◽  
Krishnakumar BALASUBRAMANIAN ◽  
Alan J. SCHROIT ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Binding Sites ◽  
Blood Platelets ◽  
Lipid Binding ◽  
Ellipsometric Measurement ◽  
Glycoprotein I ◽  
Kd Values ◽  
Low Ionic Strength ◽  
Lipid Binding Proteins

The plasma protein β2GPI (β2-glycoprotein I) has been proposed to mediate phagocytosis of apoptotic cells and to play a role in the antiphospholipid syndrome. This suggestion is based mainly on the presumption that β2GPI has an appreciable interaction with PS (phosphatidylserine)-exposing cell membranes. However, quantitative data on the binding of β2GPI to PS-exposing cells under physiologically relevant conditions are scarce and conflicting. Therefore we evaluated the binding of β2GPI to PS-expressing blood platelets. Flow cytometry showed that binding of β2GPI is negligible at physiological ionic strength, in contrast with significant binding occurring at low ionic strength. Binding parameters of β2GPI and (for comparison) prothrombin were quantified by ellipsometric measurement of protein depletion from the supernatant following incubation with platelets. At low ionic strength (20 mM NaCl, no CaCl2), a dissociation constant (Kd) of 0.2 μM was found for β2GPI, with 7.4×105 binding sites per platelet. Under physiologically relevant conditions (120 mM NaCl and 3 mM CaCl2), binding of β2GPI was not detectable (extrapolated Kd>80 μM). Prothrombin binding (at 3 mM CaCl2) was much less affected by ionic strength: Kd values of 0.5 and 1.4 μM were observed at 20 and 120 mM NaCl respectively. The low affinity and the presence of many lipid-binding proteins in plasma that can compete with the binding of β2GPI suggest that only a small fraction (<5%) of the binding sites on PS-exposing blood cells are likely to be occupied by β2GPI. These findings are discussed in relation to the alleged (patho-)physiological functions of β2GPI.

Conformational Transitions in Escherichia coli Ribosomal RNAs as Visualized by Dedicated STEM

1988 ◽  
Vol 46 ◽  
pp. 176-177
Author(s):  
J.S. Wall ◽  
V. Maridiyan ◽  
S. Tumminia ◽  
J. Hairifeld ◽  
M. Boublik
Keyword(s):  
Ionic Strength ◽  
Three Dimensional ◽  
Conformational Transitions ◽  
Dark Field ◽  
Dimensional Structure ◽  
Ribosomal Rnas ◽  
Field Mode ◽  
Freeze Dried ◽  
High Resolution Images ◽  
Low Ionic Strength

The high contrast in the dark-field mode of dedicated STEM, specimen deposition by the wet film technique and low radiation dose (1 e/Å2) at -160°C make it possible to obtain high resolution images of unstained freeze-dried macromolecules with minimal structural distortion. Since the image intensity is directly related to the local projected mass of the specimen it became feasible to determine the molecular mass and mass distribution within individual macromolecules and from these data to calculate the linear density (M/L) and the radii of gyration.2 This parameter (RQ), reflecting the three-dimensional structure of the macromolecular particles in solution, has been applied to monitor the conformational transitions in E. coli 16S and 23S ribosomal RNAs in solutions of various ionic strength.In spite of the differences in mass (550 kD and 1050 kD, respectively), both 16S and 23S RNA appear equally sensitive to changes in buffer conditions. In deionized water or conditions of extremely low ionic strength both appear as filamentous structures (Fig. la and 2a, respectively) possessing a major backbone with protruding branches which are more frequent and more complex in 23S RNA (Fig. 2a).

Sign in / Sign up

Export Citation Format

Share Document