scholarly journals Influence of Ionic Strength on Hydrophobic Interactions in Water: Dependence on Solute Size and Shape

2020 ◽  
Vol 124 (46) ◽  
pp. 10326-10336
Author(s):  
Małgorzata Bogunia ◽  
Mariusz Makowski
Keyword(s):  
Ionic Strength ◽  
Hydrophobic Interactions ◽  
Size And Shape

scholarly journals The possibility of using silochrome sorbents for proteinase inhibitor aprotinin

2020 ◽  
pp. 13-14
Author(s):  
O.G. Braginets ◽  
V.V. Ivasyk ◽  
B.O. Kondratskyi ◽  
D.L. Kachmaryk ◽  
V.L. Novak
Keyword(s):  
Ionic Strength ◽  
Electrostatic Interaction ◽  
Proteinase Inhibitor ◽  
Large Scale ◽  
Hydrophobic Interactions ◽  
High Capacity ◽  
Peristaltic Pump ◽  
Chromatographic Purification ◽  
Original Matrix ◽  
Bright Blue

Background. Aprotinin is a polypeptide, a proteinase inhibitor of natural origin. It inhibits kallikrein, kininogenase, plasmin, trypsin, chymotrypsin; blocks the activator of profibrinolysin, which helps to stop bleeding. Aprotinin is obtained from the lungs of cattle. Objective. To study the sorption of aprotinin on silochromic sorbents. Materials and methods. Affinity sorbents based on silochrome were used in the work: p-chlorobenzyl-silochrome, active bright blue K-silochrome, aminopropyl silochrome, phenyl-diol-silochrome, phenyl-glutaryl-silochrome. The optical density was measured on KFK-3 (590 nm, 750 nm) and SF-46 (280 nm). An NP-3 peristaltic pump was used for chromatographic purification. Results and discussion. Based on the obtained data, it can be assumed that the mechanism of binding of aprotinin to all carriers is obviously the same and is based on the presence of hydrophobic sites in its molecule, which leads to hydrophobic interactions with sorbents. However, increasing the hydrophobicity of the eluent does not lead to desorption of the inhibitor. Obviously, in addition to hydrophobic, a significant role is played by the electrostatic interaction, which is eliminated by increasing the ionic strength. The sorbents under study have a high capacity, they do not change their volume when the ionic strength or hydrophobicity changes, and therefore may be suitable for large-scale applications. Conclusions. Affinity sorbents based on silochrome, containing as ligands aminobenzene, p-chlorobenzyl chloride and active chlorotriazine dye of the anthraquinone series “active bright blue K”, in contrast to the original matrix – silochrome aminopropyl water and effectively dissolve. Increasing the ionic strength or hydrophobicity of desorbing solutions does not lead to elution of aprotinin due to additional electrostatic interaction. Therefore, the desorption of aprotinin is achieved only if it is eliminated in the presence of 25 % isopropanol with 1M NaCl.

scholarly journals Synthesis of Clay Composites of Polyacrylamide and Poly-2-Hydroxyethylacrylate and Sorbtion Ability in the Case of Cetylpyridinium Bromide

2015 ◽  
Vol 16 (4) ◽  
Author(s):  
M M Beysebekov
Keyword(s):  
Ionic Strength ◽  
Hydrophobic Interactions ◽  
Aqueous Suspension ◽  
Bentonite Clay ◽  
Organic Polymer ◽  
Cetylpyridinium Bromide ◽  
Composite Gels ◽  
Environment Temperature ◽  
Surface Active ◽  
Active Substances

<p>By the three-dimensional polymerization of nonionic (polyhydroxyethylacrylate and polyacrylamide) <br />polymers and bentonite clay from Manyrak deposit (East Kazakhstan Region) and with using of process <br />preliminary intercalation of monomers in an aqueous suspension of bentonite (polymerization in situ) the <br />chemically crosslinked composite gels were synthesized. Optimal conditions of synthesis and physical-chemical properties of composition gels were established. It was shown, that yield of gel fraction increases <br />with increasing contents of bentonite clay. Insignificant adding of negative charged particles of bentonite clay <br />gives to polymer gels of nonionic type polyelectrolyte character, that comes out in decreasing of swelling <br />degree of gels under effect of ionic strength. By using physical and chemical methods of research: equilibrium <br />swelling, IR spectroscopy, scanning electron microscope (SEM), sorption-desorption, etc. were shown the <br />formation of compatible, homogeneous, swelling in water polyelectrolyte gels formed via hydrogen bonds <br />between the components of the gel, stabilized by hydrophobic interactions of the organic polymer chains. <br />The possibility of the regulation of swelling ability of the composite gels through varying of the outside and <br />inside factors as: consist of the composition, conditions of intercalation, pH of the environment, temperature <br />and ionic strength was established, that is stimulus sensitivity of gels. The sorbtion capacity of polymer-clay composites in attitude surface active substance cetylpyridinium bromide were estimated. Increasing of <br />temperature of environment and content of bentonite clay in composite promotes the process of sorbtion <br />of surface-active substances. Considerably high sorption capacity of polymer clay composition based on <br />more hydrophilic polymer – polyacrylamide was established. By the results of investigations one may, that <br />synthesized polymer clay composites after suitable investigations can be recommend as sorbents of cationic <br />surface active substances.</p>

scholarly journals Increasing ionic strength and valency of cations enhance sorption through hydrophobic interactions of PFAS with soil surfaces

2022 ◽  
pp. 152975
Author(s):  
Wenwen Cai ◽  
Divina A. Navarro ◽  
Jun Du ◽  
Guangguo Ying ◽  
Bin Yang ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Hydrophobic Interactions

scholarly journals Hydrophobic-cationic peptides enhance RNA polymerase ribozyme activity by accretion

2021 ◽  
Author(s):  
Peiying Li ◽  
Philipp Holliger ◽  
Shunsuke Tagami
Keyword(s):  
Ionic Strength ◽  
Rna Polymerase ◽  
Rna Binding ◽  
Hydrophobic Interactions ◽  
Hammerhead Ribozyme ◽  
Cationic Peptides ◽  
Local Concentration ◽  
Dependent Manner ◽  
Regulatory Effects ◽  
And Function

ABSTRACTAccretion and the resulting increase in local concentration to enhance target stability and function is a widespread mechanism in biology (for example in the liquid-liquid demixing phases and coacervates). It is widely believed that such macromolecular aggregates (formed through ionic and hydrophobic interactions) may have played a role in the origin of life. Here, we report on the behaviour of a hydrophobic-cationic RNA binding peptide selected by phage display (P43: AKKVWIIMGGS) that forms insoluble aggregates, accrete RNA on their surfaces in a size-dependent manner, and thus enhance the activities of various ribozymes. At low Mg2+ concentrations ([Mg2+]: 25 mM MgCl2), the activity of a small ribozyme (hammerhead ribozyme) was enhanced by P43, while larger ribozymes (RNA polymerase ribozyme (RPR), RNase P, F1* ligase) were inhibited. In contrast, at high [Mg2+] (≥200 mM), the RPR activity was enhanced. Another hydrophobic-cationic peptide with a simpler sequence (K2V6: KKVVVVVV) also exhibited similar regulatory effects on the RPR activity. Furthermore, inactive RPR captured on P43 aggregates at low [Mg2+] could be reactivated in a high [Mg2+] buffer. Therefore, in marked contrast to previously studied purely cationic peptides (like K10) that enhance RPR only at low ionic strength, hydrophobic-cationic peptides can reversibly concentrate RNA and enhance the RPR activity even at high ionic strength conditions such as in eutectic ice phases. Such peptides could have aided the emergence of longer and functional RNAs in a fluctuating environment (e.g., dry-wet / freeze-thaw cycles) on the prebiotic earth.

scholarly journals Osmotic Pressure Measurements on Insulin: Anomalous Results Indicate that the Monomer is Preferentially Adsorbed

1986 ◽  
Vol 39 (4) ◽  
pp. 319 ◽  
Author(s):  
Peter D Jeffrey
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Osmotic Pressure ◽  
Hydrophobic Interactions ◽  
Average Molecular Weight ◽  
Adsorption Properties ◽  
Sedimentation Equilibrium ◽  
Pressure Measurements ◽  
Number Average Molecular Weight ◽  
Adsorption Analysis

The concentration dependence of the number average molecular weight of insulin at pH 2, ionic strength 0'05, and 20�C as determined by osmotic pressure measurements indicates that the .hormone is a homogeneous protein of molecular weight close to that of the dimer. Since sedimentation equilibrium experiments confirm what is well known, namely that insulin is a self-associating protein dissociating to monomer under these conditions, an explanation for the anomaly was sought in the possible loss of protein from solution by adsorption. Analysis of the results strongly supports this conclusion and consideration of the adsorption properties of insulin in terms of hydrophobic interactions shows them to be consistent with the behaviour of insulin as a self-associating protein. The monomer appears to be the primary molecular species responsible for insulin adsorption.

scholarly journals Molecular dynamics reveals complex compensatory effects of ionic strength on the SARS-CoV-2 Spike/hACE-2 interaction

2020 ◽  
Author(s):  
Anacleto Silva de Souza ◽  
Jose D. Rivera ◽  
Vitor Medeiros ◽  
Pingju Ge ◽  
Robson Francisco de Souza ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ionic Strength ◽  
Protein Conformation ◽  
Hydrophobic Interactions ◽  
Virus Entry ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Computational Simulations ◽  
Wide Range ◽  
Host Cell Surface

The SARS-CoV-2 pandemic has already killed more than 800,000 people worldwide. To gain entry, the virus uses its spike protein to bind to host hACE-2 receptors on the host cell surface and mediate fusion between viral and cell membranes. As initial steps leading to virus entry involves significant changes in protein conformation as well as in the electrostatic environment in the vicinity of the spike-hACE-2 complex, we explored the sensitivity of the interaction to changes in ionic strength through computational simulations and surface plasmon resonance. We identified two regions in the receptor-binding domain (RBD), E1 and E2, which interact differently with hACE-2. At high salt concentration, E2-mediated interactions are weakened but are compensated by strengthening E1-mediated hydrophobic interactions. These results provide a detailed molecular understanding of spike RBD/hACE-2 complex formation and stability under a wide range of ionic strengths.

scholarly journals Chromatography of plasma proteins on immobilized Cibacron Blue F3-GA. Mechanism of the molecular interaction

1982 ◽  
Vol 203 (3) ◽  
pp. 637-641 ◽  
Author(s):  
E Gianazza ◽  
P Arnaud
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Molecular Interaction ◽  
Plasma Proteins ◽  
Hydrophobic Interactions ◽  
Molecular Characteristics ◽  
Acidic Ph ◽  
Cibacron Blue ◽  
Ligand Affinity ◽  
Low Ionic Strength

Fractionation of plasma proteins on immobilized Cibacron Blue F3-GA (Affi-gel Blue) under different conditions of pH, ionic strength and temperature was studied. At acidic pH the unbound proteins were eluted in order of increasing pI (the Affi-gel Blue behaving as ion-exchanger); at basic pH and at low ionic strength they were eluted in order of decreasing molecular weight (separation by diffusion-exclusion). For the proteins that were either retarded in comparison with substances of similar molecular characteristics, or that were bound to the resin, pseudo-ligand affinity or hydrophobic interactions were also implicated.

scholarly journals Globular and asymmetric acetylcholinesterase in the synaptic basal lamina of skeletal muscle.

1994 ◽  
Vol 125 (1) ◽  
pp. 183-196 ◽  
Author(s):  
L Anglister ◽  
B Haesaert ◽  
U J McMahan
Keyword(s):  
Ionic Strength ◽  
Cell Surface ◽  
Basal Lamina ◽  
Ache Activity ◽  
Electrostatic Interactions ◽  
Neuromuscular Junctions ◽  
Hydrophobic Interactions ◽  
High Ionic Strength ◽  
Molecular Forms ◽  
Cellular Components

The aim of this study was to characterize the molecular forms of acetylcholinesterase (AChE) associated with the synaptic basal lamina at the neuromuscular junction. The observations were made on the neuromuscular junctions of cutaneous pectoris muscles of frog, Rana pipiens, which are similar to junctions of most other vertebrates including mammals, but are especially convenient for experimentation. By measuring relative AChE activity in junctional and extrajunctional regions of muscles after selective inactivation of extracellular AChE with echothiophate, or of intracellular AChE with DFP and 2-PAM, we found that &gt; 66% of the total AChE activity in the muscle was junction-specific, and that &gt; 50% of the junction-specific AChE was on the cell surface. More than 80% of the cell surface AChE was solubilized in high ionic strength detergent-free buffer, indicating that most, if not all, was a component of the synaptic basal lamina. Sedimentation analysis of that fraction indicated that while asymmetric forms (A12, A8) were abundant, globular forms sedimenting at 4-6 S (G1 and G2), composed &gt; 50% of the AChE. It was also found that when muscles were damaged in various ways that caused degeneration of axons and muscle fibers but left intact the basal lamina sheaths, the small globular forms persisted at the synaptic site for weeks after phagocytosis of cellular components; under certain damage conditions, the proportion of globular to asymmetric forms in the vacated basal lamina sheaths was as in normal junctions. While the asymmetric forms required high ionic strength for solubilization, the extracellular globular AChE could be extracted from the junctional regions of normal and damaged muscles by isotonic buffer. Some of the globular AChE appeared to be amphiphilic when examined in detergents, suggesting that it may form hydrophobic interactions, but most was non-amphiphilic consistent with the possibility that it forms weak electrostatic interactions. We conclude that the major form of AChE in frog synaptic basal lamina is globular and that its mode of association with the basal lamina differs from that of the asymmetric forms.

scholarly journals Sulfonate-Functionalized Mesoporous Silica Nanoparticles as Carriers for Controlled Herbicide Diquat Dibromide Release through Electrostatic Interaction

2019 ◽  
Vol 20 (6) ◽  
pp. 1330 ◽  
Author(s):  
Yongpan Shan ◽  
Lidong Cao ◽  
Chunli Xu ◽  
Pengyue Zhao ◽  
Chong Cao ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
Hydrophobic Interactions ◽  
Mesoporous Silica Nanoparticles ◽  
Epoxy Group ◽  
Herbicidal Activity ◽  
Sulfonate Group

Environmental stimuli-responsive pesticide release is desirable for enhanced efficiency and reduced side effects. In most cases, the loading and release of pesticides mainly depends on hydrophobic interactions and hydrogen bonding. Electrostatic interaction is less investigated as a weapon for achieving high loading content and controlled pesticide release. In this work, negative-charge decorated mesoporous silica nanoparticles (MSNs) were facilely fabricated by introducing sulfonate groups onto MSNs through a post-grafting method. Sulfonate-functionalized MSNs (MSN-SO3) were synthesized by conversion of epoxy group into sulfonate group using a bisulfite ion as a ring opening reagent. Diquat dibromide (DQ), one of the globally used quaternary ammonium herbicides, was efficiently loaded into these negatively charged MSN-SO3 nanoparticles. The loading content was increased to 12.73% compared to those using bare MSNs as carriers (5.31%). The release of DQ from DQ@MSN-SO3 nanoparticles was pH and ionic strength responsive, which was chiefly governed by the electrostatic interactions. Moreover, DQ@MSN-SO3 nanoparticles exhibited good herbicidal activity for the control of Datura stramonium L., and the bioactivity was affected by the ionic strength of the release medium. The strategy of cargo loading and release dependent on the electrostatic interactions could be generally used for charge-carrying pesticides using carriers possessing opposite charges to mitigate the potential negative impacts on the environment.

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