Net Charge and Electrophoretic Mobility of Lysozyme Charge Ladders in Solutions of Nonionic Surfactant

2007 ◽  
Vol 111 (19) ◽  
pp. 5503-5510 ◽  
Author(s):  
Jȩdrzej Szymański ◽  
Ewa Poboży ◽  
Marek Trojanowicz ◽  
Agnieszka Wilk ◽  
Piotr Garstecki ◽  
...  
Keyword(s):  
Nonionic Surfactant ◽  
Electrophoretic Mobility ◽  
Net Charge ◽  
Charge Ladders

Effects of Cooperativity in Proton Binding on the Net Charge of Proteins in Charge Ladders

2003 ◽  
Vol 107 (19) ◽  
pp. 4653-4666 ◽  
Author(s):  
Upma Sharma ◽  
Russell S. Negin ◽  
Jeffrey D. Carbeck
Keyword(s):  
Net Charge ◽  
Proton Binding ◽  
Charge Ladders

scholarly journals THE STEPWISE MUTATION MODEL: AN EXPERIMENTAL EVALUATION UTILIZING HEMOGLOBIN VARIANTS

Genetics ◽  
1980 ◽  
Vol 94 (1) ◽  
pp. 185-201
Author(s):  
Paul A Fuerst ◽  
Robert E Ferrell
Keyword(s):  
Amino Acid ◽  
Electrophoretic Mobility ◽  
Tertiary Structure ◽  
Stepwise Mutation Model ◽  
Starch Gel Electrophoresis ◽  
Human Hemoglobin ◽  
Net Charge ◽  
Mutation Model ◽  
Stepwise Mutation ◽  
Hemoglobin Variants

ABSTRACT The stepwise mutation model of OHTA and KIMURA (1973) was proposed to explain patterns of genetic variability revealed by means of electrophoresis. The assumption that electrophoretic mobility was principally determined by unit changes in net molecular charge has been criticized by JOHNSON (1974, 1977). This assumption has been tested directly using hemoglobin. Twenty-seven human hemoglobin variants with known amino acid substitutions, and 26 nonhuman hemoglobins with known sequences were studied by starch gel electrophoresis. Of these hemoglobin% 60 to 70% had electrophoretic mobilities that could be predicted solely on the basis of net charge calculated from the amino acid composition alone, ignoring tertiary structure. Only four hemoglobins showed a mobility that was clearly different from an expected mobility calculated using only the net charge of the molecule. For the remaining 30% of hemoglobins studied, mobility was determined by a combination. of net charge and other unidentified components, probably reflecting changes in ionization of some amino acid residues as a result of small alterations in tertiary structure due to the amino acid substitution in the variant. For the nonhuman hemoglobins, the deviation of a sample from its expected mobility increased with increasing amino acid divergence from human hemoglobin A.—It is concluded that the net electrostatic charge of a molecule is the principal determinant of electrophoretic mobility under the conditions studied. However, because of the significant deviation from strict stepwise mobility detected for 30 to 40% of the variants studied, it is further concluded that the infinite-allele model of KIMURA and CROW (1964) or a "mixed model" such as that proposed by LI (1976) may be more appropriate than the stepwise mutation model for the analysis of much of the available electrophoretic data from natural populations.

Correlation between Net Charge of Antigens and Electrophoretic Mobility of Immunoglobulin M Antibodies

Nature ◽  
1967 ◽  
Vol 213 (5080) ◽  
pp. 1013-1014 ◽  
Author(s):  
JOHN B. ROBBINS ◽  
EDNA MOZES ◽  
ABRAHAM RIMON ◽  
MICHAEL SELA
Keyword(s):  
Electrophoretic Mobility ◽  
Immunoglobulin M ◽  
Net Charge

scholarly journals EVALUATION OF THE STEPWISE MUTATION MODEL OF ELECTROPHORETIC MOBILITY: COMPARISON OF THE GEL SIEVING BEHAVIOR OF ALLELES AT THE ESTERASE-5 LOCUS OF DROSOPHILA PSEUDOOBSCURA

Genetics ◽  
1977 ◽  
Vol 87 (1) ◽  
pp. 139-157
Author(s):  
George B Johnson
Keyword(s):  
Electrophoretic Mobility ◽  
Drosophila Pseudoobscura ◽  
Conformational Heterogeneity ◽  
Net Charge ◽  
Free Mobility ◽  
Mutation Model ◽  
Protein Properties ◽  
Stepwise Mutation ◽  
The One ◽  
Multiple Variants

ABSTRACT Seven alleles at the esterase-5 locus of Drosophila pseudoobscura appear approximately uniformly spaced on 5% acrylamide gels. Such stepwise "ladders" in mobility have been used to argue for the charge-state model of electrophoretic mobility. To evaluate this interpretation, flies of the seven strains were examined in replicate electrophoresis on polyacrylamide gels of differing pore size, permitting estimation of the relative contributions of charge and of size/conformation to electrophoretic mobility. Six of the seven strains examined proved to be heterogeneous, containing multiple variants that migrate to similar positions on 5% acrylamide gels. In the one strain genetically analyzed to date, the hidden variants segregate in crosses. A total of fourteen variants are detected by this gel sieving analysis, many of them involving apparent conformational differences. Thus, protein properties in addition to net charge appear to play an important role in determining the degree of mobility difference between alleles. Examining estimates of free mobility, uniform charge differences are the rule within conformational classes. However, the superposition of conformational heterogeneity renders interpretation of mobility spacing solely in terms of such charge differences inappropriate.

Characteristics of an Electrostatic Phase Plate

1972 ◽  
Vol 30 ◽  
pp. 618-619
Author(s):  
William Krakow ◽  
Benjamin Siegel
Keyword(s):  
Phase Contrast ◽  
Objective Lens ◽  
Phase Plate ◽  
Net Charge ◽  
Phase Plates ◽  
Beam Currents ◽  
Contrast Image ◽  
Bright Phase ◽  
Additional Phase Shift ◽  
Additional Phase

Unwin has used a metallized non-conducting thread in the back focal plane of the objective lens that stops out a portion of the unscattered beam, takes on a localized positive charge and thus produces an additional phase shift to give a different transfer function of the lens. Under the particular conditions Unwin used, the phase contrast image was shifted to bright phase contrast for optimum focus.We have investigated the characteristics of this type of electrostatic phase plate, both analytically and experimentally, as functions of the magnitude of charge and defocus. Phase plates have been constructed by using Wollaston wire to mount 0.25μ diameter platinum wires across apertures ranging from 50 to 200μ diameter and vapor depositing SiO and gold on the mounted wires to give them the desired charging characteristics. The net charge was varied by adjusting only the bias on the Wehnelt shield of the gun, and hence the beam currents and effective size of the source.

Direct imaging of charge transfer

1996 ◽  
Vol 54 ◽  
pp. 680-681
Author(s):  
Yimei Zhu ◽  
J. Tafto
Keyword(s):  
Charge Transfer ◽  
Electron Diffraction ◽  
Scattering Amplitude ◽  
High Temperature Superconductors ◽  
Charge Carriers ◽  
Image Charge ◽  
Net Charge ◽  
Long Time ◽  
Electron Holes ◽  
First Time

The electron holes confined to the CuO2-plane are the charge carriers in high-temperature superconductors, and thus, the distribution of charge plays a key role in determining their superconducting properties. While it has been known for a long time that in principle, electron diffraction at low angles is very sensitive to charge transfer, we, for the first time, show that under a proper TEM imaging condition, it is possible to directly image charge in crystals with a large unit cell. We apply this new way of studying charge distribution to the technologically important Bi2Sr2Ca1Cu2O8+δ superconductors.Charged particles interact with the electrostatic potential, and thus, for small scattering angles, the incident particle sees a nuclei that is screened by the electron cloud. Hence, the scattering amplitude mainly is determined by the net charge of the ion. Comparing with the high Z neutral Bi atom, we note that the scattering amplitude of the hole or an electron is larger at small scattering angles. This is in stark contrast to the displacements which contribute negligibly to the electron diffraction pattern at small angles because of the short g-vectors.

Factor VIII-Related Activities in Normal, Haemophilic and von Willebrand’s Disease Platelet Fractions

1978 ◽  
Vol 40 (02) ◽  
pp. 288-301 ◽  
Author(s):  
P Meucci ◽  
I R Peake ◽  
A L Bloom
Keyword(s):  
Factor Viii ◽  
Electrophoretic Mobility ◽  
Concanavalin A ◽  
Freezing And Thawing ◽  
Von Willebrand's Disease ◽  
Factor Viii Related Antigen ◽  
Von Willebrand’S Disease ◽  
Normal Plasma ◽  
Significant Difference ◽  
Ristocetin Cofactor

SummaryFactor VIII-related activities have been studied in platelet fractions in order to try to reconcile the conflicting findings of other workers, and to extend the studies. In platelets from 16 normal subjects procoagulant factor VIII was not detected. The amount of factor VIII-related antigen (FVIIIR: AG) in the cytosol per mg of protein was about twice that in the membrane fraction and about ten times that in the debris fraction. There was no significant difference between the amount of FVIIIR: AG and ristocetin cofactor (RistCof) activity in each fraction. The findings in haemophilic platelets were similar. In von Willebrand’s disease (vWd) one serverely affected patient had no detectable factor VIII related activities in any platelet fraction. In 5 patients with intermediate vWd results were normal. In a further 5, with more prolonged bleeding times, no FVIIIR: RistCof was detected in platelets, despite a normal amount of FVIIIR: AG in the cytosol and debris. The electrophoretic mobility of cytosol FVIIIR: AG was increased in all normals and patients, while that in the membrane and debris fractions had normal mobility. Cytosol FVIIIR: AG eluted later than normal FVIIIR: AG on gel filtration on Sepharose 2B, and also showed reduced antibody binding in an immunoradiometric assay. Precipitation of FVIIIR: AG by concanavalin A was incomplete in all platelet fractions from normals, and even more reduced in vWd platelet fractions. The results suggest the possibility of two types of platelet FVIIIR: AG.A factor VIII-related antigen was shown to be associated with normal washed platelets by immunofluorescence techniques (Bloom et al. 1973). Since then, several studies have been reported on the localisation of factor VIII related antigen (FVIIIR: AG), factor VIII procoagulant activity (FVIII: C) and factor VIII related ristocetin cofactor activity (FVIIIR: RistCof) within the platelets. Initially, Howard et al. (1974) indicated that FVIIIR: AG was firmly bound to the platelet membrane, and noted that in lysed platelets the level of FVIIIR: AG as measured by electroimmunodiffusion was higher than that in whole platelet suspensions. However, further studies by Nachman and Jaffe (1975) showed that FVIIIR: AG was also present to a considerable extent in the granules, and they detected none in the platelet cytosol. Bouma and colleagues (1975) were, however, able to find FVIIIR: AG and FVIIIR: RistCof in the cytosol upon freezing and thawing platelets. This FVIIIR: AG had an electrophoretic mobility comparable to that of normal plasma. They also noted that platelets which were air dried apparently had a granular FVIIIR:AG localisation by immunfluorescence; however, intact platelets in suspension did not stain by this method.Recently Ruggeri et al. (1977) and Sultan et al. (1977) have also found FVIIIR: AG in the cytosol, and the former authors reported it to have increased electrophoretic mobility when compared to normal plasma FVIIIR:AG. Results concerning the localisation of FVIIIR: AG in normal platelets have thus been conflicting. Similarly, in the few reports available concerning platelet FVIIIR: AG in von Willibrand’s disease variable results have also been obtained (Ruggeri et al. 1977, Howard et al. 1974, Shearn et al. 1974 and Bouma et al. 1975).In this study we report on the localisation of factor VIII-related activities in normal, haemophilic and von Willebrand’s disease platelets using available standard techniques as well as precipitation of FVIIIR: AG with the plant lectin concanavalin A, a procedure which has been shown to detect abnormal forms of FVIIIR:AG in certain types of von Willebrand’s disease (Peake and Bloom 1977).

Assessment of Damage to Human Platelets after Aggregation and Other Injuries by Microscopic Observation and Estimation of Serotonin Uptake

1970 ◽  
Vol 23 (02) ◽  
pp. 261-275 ◽  
Author(s):  
G Zbinden ◽  
J. N Mehrishi ◽  
S Tomlin
Keyword(s):  
Platelet Aggregation ◽  
Electrophoretic Mobility ◽  
Human Platelets ◽  
Freezing And Thawing ◽  
Low Degree ◽  
Microscopic Evaluation ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Charged Macromolecules ◽  
5 Ht Uptake

SummaryThe severity of platelet damage induced by hyper- and hypotonic NaCl solutions and freezing and thawing was assessed by microscopic evaluation and measuring inhibition of 5-HT uptake. The same techniques were used to quantitate the effects of aggregating agents. The positively charged macromolecules PS, Poly-L und Poly-O reduced the net negative surface charge as determined by microelectrophoresis, caused platelet aggregation and inhibited 5-HT uptake. The damaging effects of Poly-L and Poly-O were more severe and more closely related to concentration than that of PS. The negatively charged macromolecules Poly-IC and NaPS increased the anodic electrophoretic mobility. Poly-IC and heparin caused a low degree of platelet clumping and no inhibition of 5-HT uptake. NaPS produced severe platelet damage with extensive clumping and complete inhibition of 5-HT uptake. Na laurate had the same effect, but did not alter electrophoretic mobility. ADP caused concentration-dependent platelet aggregation and inhibition of 5-HT uptake. The effects of ADP and NaPS were compared in agitated and non-agitated platelet samples containing identical concentrations of the 2 compounds. Agitation was found to increase the degree of platelet clumping and to reduce 5-HT uptake.

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