scholarly journals Electrothermal supercharging of proteins in native MS: effects of protein isoelectric point, buffer, and nanoESI-emitter tip size

The Analyst ◽  
2016 ◽  
Vol 141 (19) ◽  
pp. 5598-5606 ◽  
Author(s):  
Daniel N. Mortensen ◽  
Evan R. Williams
Keyword(s):  
Isoelectric Point ◽  
Native Ms ◽  
Positively Charged

The extent of charging resulting from electrothermal supercharging increases with decreasing tip size for positively charged proteins.

Formation mechanism of spherical oxide particles containing dye

1999 ◽  
Vol 14 (5) ◽  
pp. 2088-2091
Author(s):  
Sixin Wu ◽  
Congshan Zhu
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Formation Mechanism ◽  
Isoelectric Point ◽  
Sol Gel ◽  
Diameter Distribution ◽  
Maximum Particle Size ◽  
Maximum Particle ◽  
Oxide Particles ◽  
Positively Charged

2-[3-(1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidine)-1-propenyl]-1,3,3-trimethyl-3H-indolium idoide (HICI) dye-doped SiO2 particles were synthesized by sol-gel method. Dimension, diameter, distribution, and homogeneity of the particles are closely related to the positively charged dye concentration, corresponding to the zeta potential of the particles. When the dye concentration reaches about 7.8 × 10−4 mol/mol SiO2, corresponding to the isoelectric point of the particles, the maximum particle size and the most homogeneity can be reached.

Restricted transport of cationic macromolecules across intestinal capillaries

1983 ◽  
Vol 245 (4) ◽  
pp. G568-G572 ◽  
Author(s):  
M. A. Perry ◽  
J. N. Benoit ◽  
P. R. Kvietys ◽  
D. N. Granger
Keyword(s):  
Steady State ◽  
Lactate Dehydrogenase ◽  
Plasma Concentration ◽  
Reflection Coefficient ◽  
Isoelectric Point ◽  
Molecular Size ◽  
P Values ◽  
Osmotic Reflection Coefficient ◽  
Positively Charged ◽  
Lactate Dehydrogenase Isoenzymes

The charge-selective properties of intestinal capillaries were investigated by measuring steady-state lymph-to-plasma concentration ratios (L/P) of endogenous and exogenous macromolecules of comparable molecular size but different charge. The steady-state L/P values for endogenous lactate dehydrogenase isoenzymes (LD1-LD5) decreased with increasing isoelectric point. The osmotic reflection coefficient for LD1, the most negative isoenzyme studied, was 0.71 +/- 0.01; that for the most positive isoenzyme (LD5) was 0.95 +/- 0.01. The steady-state L/P for an exogenous molecule, neutral dextran, was 0.51 +/- 0.04; the L/P for the positively charged dextran of similar size was 0.25 +/- 0.04. The results indicate that intestinal capillaries behave as a positively charged barrier that reduces blood-lymph exchange of cationic macromolecules and enhances the exchange of anionic molecules.

scholarly journals ELECTRICAL CHARGES OF COLLOIDAL PARTICLES AND ANOMALOUS OSMOSIS

1922 ◽  
Vol 4 (4) ◽  
pp. 463-486 ◽  
Author(s):  
Jacques Loeb
Keyword(s):  
Isoelectric Point ◽  
Salt Solution ◽  
Electrical Transport ◽  
Colloidal Particles ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Trivalent Cation ◽  
Hydrogen Ion Concentration ◽  
Donnan Equilibrium ◽  
Positively Charged

1. It has been shown in previous publications that when solutions of different concentrations of salts are separated by collodion-gelatin membranes from water, electrical forces participate in addition to osmotic forces in the transport of water from the side of the water to that of the solution. When the hydrogen ion concentration of the salt solution and of the water on the other side of the membrane is the same and if both are on the acid side of the isoelectric point of gelatin (e.g. pH 3.0), the electrical transport of water increases with the valency of the cation and inversely with the valency of the anion of the salt in solution. Moreover, the electrical transport of water increases at first with increasing concentration of the solution until a maximum is reached at a concentration of about M/32, when upon further increase of the concentration of the salt solution the transport diminishes until a concentration of about M/4 is reached, when a second rise begins, which is exclusively or preeminently the expression of osmotic forces and therefore needs no further discussion. 2. It is shown that the increase in the height of the transport curves with increase in the valency of the cation and inversely with the increase in the valency of the anion is due to the influence of the salt on the P.D. (E) across the membrane, the positive charge of the solution increasing in the same way with the valency of the ions mentioned. This effect on the P.D. increases with increasing concentration of the solution and is partly, if not essentially, the result of diffusion potentials. 3. The drop in the transport curves is, however, due to the influence of the salts on the P.D. (ϵ) between the liquid inside the pores of the gelatin membrane and the gelatin walls of the pores. According to the Donnan equilibrium the liquid inside the pores must be negatively charged at pH 3.0 and this charge is diminished the higher the concentration of the salt. Since the electrical transport is in proportion to the product of E x ϵ and since the augmenting action of the salt on E begins at lower concentrations than the depressing action on ϵ, it follows that the electrical transport of water must at first rise with increasing concentration of the salt and then drop. 4. If the Donnan equilibrium is the sole cause for the P.D. (ϵ) between solid gelatin and watery solution the transport of water through collodion-gelatin membranes from water to salt solution should be determined purely by osmotic forces when water, gelatin, and salt solution have the hydrogen ion concentration of the isoelectric point of gelatin (pH = 4.7). It is shown that this is practically the case when solutions of LiCl, NaCl, KCl, MgCl2, CaCl2, BaCl2, Na2SO4, MgSO4 are separated by collodion-gelatin membranes from water; that, however, when the salt has a trivalent (or tetravalent?) cation or a tetravalent anion a P.D. between solid isoelectric gelatin and water is produced in which the wall assumes the sign of charge of the polyvalent ion. 5. It is suggested that the salts with trivalent cation, e.g. Ce(NO3)3, form loose compounds with isoelectric gelatin which dissociate electrolytically into positively charged complex gelatin-Ce ions and negatively charged NO3 ions, and that the salts of Na4Fe(CN)6 form loose compounds with isoelectric gelatin which dissociate electrolytically into negatively charged complex gelatin-Fe(CN)6 ions and positively charged Na ions. The Donnan equilibrium resulting from this ionization would in that case be the cause of the charge of the membrane.

The Effect of Charge and Mechanical Loading on Antibody Diffusion Through the Articular Surface of Cartilage

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Chris D. DiDomenico ◽  
Lawrence J. Bonassar
Keyword(s):  
Mechanical Loading ◽  
Isoelectric Point ◽  
Articular Surface ◽  
Molecular Transport ◽  
Past Research ◽  
Convective Transport ◽  
Cartilage Matrix ◽  
Cartilage Sample ◽  
Transport Enhancement ◽  
Positively Charged

Molecular transport of osteoarthritis (OA) therapeutics within articular cartilage is influenced by many factors, such as solute charge, that have yet to be fully understood. This study characterizes how solute charge influences local diffusion and convective transport of antibodies within the heterogeneous cartilage matrix. Three fluorescently tagged solutes of varying isoelectric point (pI) (4.7–5.9) were tested in either cyclic or passive cartilage loading conditions. In each case, local diffusivities were calculated based on local fluorescence in the cartilage sample, as observed by confocal microscopy. In agreement with past research, local solute diffusivities within the heterogeneous cartilage matrix were highest around 200–275 μm from the articular surface, but 3–4 times lower at the articular surface and in the deeper zones of the tissue. Transport of all 150 kDa solutes was significantly increased by the application of mechanical loading at 1 Hz, but local transport enhancement was not significantly affected by changes in solute isoelectric point. More positively charged solutes (higher pI) had significantly higher local diffusivities 200–275 μm from the tissue surface, but no other differences were observed. This implies that there are certain regions of cartilage that are more sensitive to changes in solute charge than others, which could be useful for future development of OA therapeutics.

scholarly journals EFFECT OF ELECTROLYTES ON ELECTROSURFACE PROPERTIES OF MICROCRYSTALLINE CELLU-LOSE PARTICLES

2021 ◽  
pp. 55-60
Author(s):  
Aleksandr Valentinovich Lorentsson ◽  
Nadezhda Leonidovna Koroleva ◽  
Yuriy Mitrofanovich Chernoberezhskii
Keyword(s):  
Isoelectric Point ◽  
Specific Adsorption ◽  
Point Of Zero Charge ◽  
Ph Values ◽  
Zero Charge ◽  
Anions And Cations ◽  
Acidic Region ◽  
Charge Point ◽  
Positively Charged ◽  
Specific Adsorption Of Ions

The electrical surface properties (specific surface charge of particles - σ0, point of zero charge – pHPZC, electrokinetic potential - ζ and position of isoelectric point - pHIEP) of dispersions of microcrystalline cellulose (MCC) in aqueous solutions of H2SO4, NaOH, Na2SO4 and TiOSO4 were investigated. Significant effects of specific adsorption of anions and cations on pHPZC and pHIEP have been demonstrated. The isoelectric point of the MCC particles in the H2SO4 solution is at pH 2.0, while the zero charge point in 5·10-4 M solution Na2SO4 at pH 5.6. An explanation of the observed effects is given. Possible schemes of the structure of the electrical double layer at different pH values, taking into account specific adsorption of ions in the Stern layer, are given. The introduction of TiOSO4 (10-5 mol/dm3) shifts the position of IEP to a less acidic region (pHIEP 4.5) due to the specific adsorption of positively charged TiOSO4 hydrolysis products particles.

scholarly journals ON THE NATURE OF FORCES OPERATING IN BLOOD CLOTTING

1945 ◽  
Vol 29 (2) ◽  
pp. 113-122 ◽  
Author(s):  
W. F. H. M. Mommaerts
Keyword(s):  
Hydrogen Bonds ◽  
Isoelectric Point ◽  
Blood Clotting ◽  
Electrostatic Attraction ◽  
Primary Reaction ◽  
Ph Values ◽  
Positively Charged

It is found that clotting of fibrinogen by thrombin does not occur on the acid side of the isoelectric point of the fibrinogen. At such pH values, however, a primary reaction between thrombin and fibrinogen takes place, leading to the formation of profibrin, a compound of thrombin and fibrinogen. At pH values at which clotting is possible, fibrinogen is negatively, thrombin positively charged, whereas profibrin has a pattern of positive and negative charges. The primary reaction, the formation of profibrin by combination of thrombin and fibrinogen, is inhibited by urea but not by neutral salts. The combination of thrombin with fibrinogen most probably takes place by hydrogen bonds. The second reaction, the polymerisation of profibrin to fibrin, is inhibited by neutral salts in the same way as complex or autocomplex coacervates. It is caused therefore by electrostatic attraction between the positive and the negative charges of the profibrin.

Positively Charged Latex

1941 ◽  
Vol 14 (3) ◽  
pp. 656-658
Author(s):  
B. V. Coplan ◽  
S. S. Rogers ◽  
L. A. Hansen
Keyword(s):  
Isoelectric Point ◽  
Rubber Particle ◽  
Negative Ion ◽  
Basic Solution ◽  
Colloidal Systems ◽  
Net Charge ◽  
Basic Solutions ◽  
Positive Ion ◽  
Positively Charged ◽  
Long Chain

Abstract Latex, like many other colloidal systems, owes its stability to a large extent to the electrical charge carried by each particle in suspension. One possible explanation of how the particles become charged is that the protein adsorbed on the rubber hydrocarbon is capable of ionizing to a slight extent, both as an acid and as a base, much in the same manner as do amino acids. In a highly basic solution the rubber particle acquires a negative charge; whereas in an acid solution the charge is positive. At some stage between strongly acid and strongly basic solutions, the ionization of the adsorbed protein layer would be as much acidic as basic, and the particle would have no net charge. This is known as the isoelectric point, and has been found to be at a pH of 4.2. At or near the isoelectric point, the latex is very unstable, and coagulates rapidly. The charge carried by the particle may, of course, be due also to adsorption of ions from solution. The latex particles are normally negatively charged, but the sign of the charge can be reversed by the addition of acid, by the presence of polyvalent cations, and more recently it has been shown that cationic soaps may reverse the charge. In a cationic soap the positive ion is a long chain, and the negative ion is a halide, sulfate, etc. The hydrophilic group attached to the long chain of carbon atoms is a quaternary ammonium, sulfonium, or phosphonium group. The authors felt that, because positively charged latex seems to have some commercial possibilities, it would be of interest to attempt to prepare latex suspensions of reversed charge of higher concentrations than those used by Blow, which were apparently around 5 per cent.

Protamine-DNA interaction

1978 ◽  
Vol 36 (2) ◽  
pp. 200-201
Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer
Keyword(s):  
Small Volume ◽  
Double Helix ◽  
Dna Interaction ◽  
Dark Field ◽  
Sperm Head ◽  
Nuclear Proteins ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Dna Double Helix ◽  
Positively Charged

Dark field electron microscopy has been used for the study of the structure of individual macromolecules with a resolution to at least the 5Å level. The use of this technique has been extended to the investigation of structure of interacting molecules, particularly the interaction between DNA and fish protamine, a class of basic nuclear proteins of molecular weight 4,000 daltons.Protamine, which is synthesized during spermatogenesis, binds to chromatin, displaces the somatic histones and wraps up the DNA to fit into the small volume of the sperm head. It has been proposed that protamine, existing as an extended polypeptide, winds around the minor groove of the DNA double helix, with protamine's positively-charged arginines lining up with the negatively-charged phosphates of DNA. However, viewing protamine as an extended protein is inconsistent with the results obtained in our laboratory.

Structure and Interaction of Protamine by Dark Field Electron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 160-161
Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer
Keyword(s):  
Electron Microscopy ◽  
Dark Field ◽  
Amino Acid Sequences ◽  
Dimensional Structure ◽  
3 Dimensional ◽  
Field Electron ◽  
Proposed Model ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Positively Charged

It has been shown for some time that it is possible to obtain images of small unstained proteins, with a resolution of approximately 5Å using dark field electron microscopy (1,2). Applying this technique, we have observed a uniformity in size and shape of the 2-dimensional images of pure specimens of fish protamines (salmon, herring (clupeine, Y-l) and rainbow trout (Salmo irideus)). On the basis of these images, a model for the 3-dimensional structure of the fish protamines has been proposed (2).The known amino acid sequences of fish protamines show stretches of positively charged arginines, separated by regions of neutral amino acids (3). The proposed model for protamine structure (2) consists of an irregular, right-handed helix with the segments of adjacent arginines forming the loops of the coil.

Enhanced type I photoreaction of indocyanine green via electrostatic-force-driven aggregation

Nanoscale ◽  
2020 ◽  
Vol 12 (17) ◽  
pp. 9517-9523 ◽  
Author(s):  
Huizhen Fan ◽  
Yu Fan ◽  
Wenna Du ◽  
Rui Cai ◽  
Xinshuang Gao ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Indocyanine Green ◽  
Electrostatic Force ◽  
Type I ◽  
Positively Charged

ICG forms aggregates in positively charged mesoporous silica, which show an enhanced type I photoreaction pathway.

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