scholarly journals Chaotropic and Kosmotropic Anions Regulate the Outcome of Enzyme-Mediated Dynamic Combinatorial Libraries of Cyclodextrins in Two Different Ways

2021 ◽  
Vol 9 ◽  
Author(s):  
Andreas Erichsen ◽  
Dennis Larsen ◽  
Sophie R. Beeren
Keyword(s):  
Specific Binding ◽  
Combinatorial Libraries ◽  
Hofmeister Series ◽  
Cyclodextrin Glucanotransferase ◽  
Binding Interactions ◽  
Guest Molecules ◽  
High Concentrations ◽  
Chaotropic Anions

We demonstrate how different anions from across the Hofmeister series can influence the behavior of enzyme-mediated dynamic combinatorial libraries of cyclodextrins (CDs). Using cyclodextrin glucanotransferase to catalyze reversible transglycosylation, dynamic mixtures of interconverting cyclodextrins can be formed wherein the relative concentrations of α-CD, β-CD and γ-CD is determined by their intrinsic stabilities and any stabilizing influences of added template (guest) molecules. Here, we find that addition of high concentrations of kosmotropic anions can be used to enhance the effects of added hydrophobic templates, while chaotropic anions can themselves act as templates, causing predictable and significant changes in the cyclodextrin composition due to weak, but specific, binding interactions with α-CD.

The many-body expansion for aqueous systems revisited: III. Hofmeister ion–water interactions

2021 ◽  
Author(s):  
Kristina M. Herman ◽  
Joseph P. Heindel ◽  
Sotiris S. Xantheas
Keyword(s):  
Water Molecules ◽  
Hofmeister Series ◽  
Aqueous Systems ◽  
Many Body ◽  
Ionic Clusters ◽  
Anions And Cations ◽  
Chaotropic Anions ◽  
The Many ◽  
Body Energy

We report a Many Body Energy (MBE) analysis of aqueous ionic clusters containing kosmotropic and chaotropic anions and cations at the two opposite ends of the Hofmeister series to quantify how these ions alter the interaction between the water molecules in their immediate surroundings.

scholarly journals Colchicine-binding protein of the liver. Its characterization and relation to microtubules.

1975 ◽  
Vol 66 (3) ◽  
pp. 609-620 ◽  
Author(s):  
C Patzelt ◽  
A Singh ◽  
Y L Marchand ◽  
L Orci ◽  
B Jeanrenaud
Keyword(s):  
High Speed ◽  
Specific Binding ◽  
Electrophoretic Analysis ◽  
Binding Activity ◽  
Low Concentrations ◽  
Electrophoretic Behavior ◽  
High Affinity Binding Site ◽  
High Concentrations

Colchicine-binding activity of mouse liver high-speed supernate has been investigated. It has been found to be time and temperature dependent. Two binding activities with different affinities for colchicine seem to be present in this high-speed supernate, of which only the high-affinity binding site (half maximal binding at 5 x 10(-6) M colchicine) can be attributed to microtubular protein by comparison with purified tubulin. Vinblastine interacted with this binding activity by precipitating it when used at high concentrations (2 x 10(-3) M), and by stabilizing it at low concentrations (10(-5) M). Lumicolchicine was found not to compete with colchicine. The colchicine-binding activity was purified from liver and compared with that of microtubular protein from brain. The specific binding activity of the resulting preparation, its electrophoretic behavior, and the electron microscope appearance of the paracrystals obtained upon its precipitation with vinblastine permitted its identification as microtubular protein (tubulin). Electrophoretic analysis of the proteins from liver supernate that were precipitated by vinblastine indicated that this drug was not specific for liver tubulin. Preincubation of liver supernate with 5 mM EGTA resulted in a time-dependent decrease of colchicine-binding activity, which was partly reversed by the addition of Ca++. However, an in vitro formation of microtubules upon lowering the Ca++ concentration could not be detected. Finally, a method was developed enabling that portion of microtubular protein which was present as free tubulin to be measured and to be compared with the total amount of this protein in the tissue. This procedure permitted demonstration of the fact that, under normal conditions, only about 40% of the tubulin of the liver was assemled as microtubules. It is suggested that, in the liver, rapid polymerization and depolymerization of microtubules occur and may be an important facet of the functional role of the microtubular system.

Adsorption behaviour of a CdII–triazole MOF for butan-2-one in a single-crystal-to-single-crystal (SCSC) fashion: the role of hydrogen bonding and C—H...π interactions

2019 ◽  
Vol 75 (6) ◽  
pp. 806-811
Author(s):  
Jia Wang ◽  
Tianchao You ◽  
Teng Wang ◽  
Qikui Liu ◽  
Jianping Ma ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Single Crystal ◽  
Specific Binding ◽  
Supramolecular Interactions ◽  
Adsorption Behaviour ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Π Interactions ◽  
H Nmr

The adsorption behaviour of the CdII–MOF {[Cd(L)2(ClO4)2]·H2O (1), where L is 4-amino-3,5-bis[3-(pyridin-4-yl)phenyl]-1,2,4-triazole, for butan-2-one was investigated in a single-crystal-to-single-crystal (SCSC) fashion. A new host–guest system that encapsulated butan-2-one molecules, namely poly[[bis{μ3-4-amino-3,5-bis[3-(pyridin-4-yl)phenyl]-1,2,4-triazole}cadmium(II)] bis(perchlorate) butanone sesquisolvate], {[Cd(C24H18N6)2](ClO4)2·1.5C4H8O} n , denoted C4H8O@Cd-MOF (2), was obtained via an SCSC transformation. MOF 2 crystallizes in the tetragonal space group P43212. The specific binding sites for butan-2-one in the host were determined by single-crystal X-ray diffraction studies. N—H...O and C—H...O hydrogen-bonding interactions and C—H...π interactions between the framework, ClO4 − anions and guest molecules co-operatively bind 1.5 butan-2-one molecules within the channels. The adsorption behaviour was further evidenced by 1H NMR, IR, TGA and powder X-ray diffraction experiments, which are consistent with the single-crystal X-ray analysis. A 1H NMR experiment demonstrates that the supramolecular interactions between the framework, ClO4 − anions and guest molecules in MOF 2 lead to a high butan-2-one uptake in the channel.

LIPOPROTEIN BINDING TOHUMAN PLATELETS IS LOCATED AT GPIIb/IIIa COMPLEX

1987 ◽  
Author(s):  
E Koller ◽  
F Koller
Keyword(s):  
Specific Binding ◽  
Human Platelets ◽  
Plasma Lipoproteins ◽  
High Density Lipoproteins ◽  
Molecular Weights ◽  
Disulfide Reduction ◽  
Specific Binding Sites ◽  
First Results ◽  
Lipoprotein Binding ◽  
High Concentrations

Human Platelets possess specific binding sites for low density lipoproteins (LDL) and high density lipoproteins(HDL)(1). Binding of both classes of plasma lipoproteins, though competitive, has been shown by several groups to facilitate platelet activation.Isolated washed platelets occasionally aggregate upon addition of high concentrations of LDL even in the absence of known platelet activators. The proteins responsible for this binding have been visualized by ligand blotting (2). Both types of ligand specifically bind to two glycoproteins with molecular weights of 135 and 115 kD, respectively. The conditions of binding to these two proteins, however, markedly differ from those known for other lipoprotein receptors.Following extensive purification, these two species are still present at concentrations relative to each other that depend markedly on the conditions of purification. The purified, solubilized receptor was tested under various conditions, including in the absence and presence of calcium, after disulfide-reduction, and following chymotrypsin digestion. In parallel experiments, the same preparations were tested with respect to binding of fibrinogen, different lectins, and thealloantibody anti-PlAI . The results strongly support the assumption, that the two protein bands associated with lipoprotein binding are constituents of the GP-IIb/IIIa complex.These first results may have greatimplications for our understanding ofthe mechanism by which lipoproteins facilitate platelet stimulation.

Glycine-extended gastrin regulates HEK cell growth

1999 ◽  
Vol 277 (2) ◽  
pp. R572-R581 ◽  
Author(s):  
Vinzenz M. Stepan ◽  
Dieter F. Krametter ◽  
Masashi Matsushima ◽  
Andrea Todisco ◽  
John Delvalle ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Cell Line ◽  
Thymidine Incorporation ◽  
Specific Binding ◽  
Biological Effects ◽  
Human Kidney ◽  
Hek 293 ◽  
High Concentrations

Posttranslational processing of progastrin to a carboxy terminally amidated form (G-NH2) is essential for its effect on gastric acid secretion and other biological effects mediated by gastrin/CCK-B receptors. The immediate biosynthetic precursor of G-NH2, glycine-extended gastrin (G-Gly), does not stimulate gastric acid secretion at physiological concentrations but is found in high concentrations during development. G-NH2 and G-Gly have potent growth stimulatory effects on gastrointestinal tissues, and G-NH2 can stimulate proliferation of human kidney cells. Thus we sought to explore the actions of G-NH2 and G-Gly on the human embryonic kidney cell line HEK 293. HEK 293 cells showed specific binding sites for 125I-labeled Leu15-G17-NH2and125I-Leu15-G2—17-Gly. Both G-NH2 and G-Gly induced a dose-dependent increase in [3H]thymidine incorporation, and both peptides together significantly increased [3H]thymidine incorporation above the level of either peptide alone. G-NH2 and G-Gly were detected by radioimmunoassay in serum-free conditioned media. Antibodies directed against G-NH2 and G-Gly lead to a significant reduction in [3H]thymidine incorporation. G-NH2 but not G-Gly increased intracellular Ca2+concentration. We conclude that G-NH2 and G-Gly act cooperatively via distinct receptors to stimulate the growth of a nongastrointestinal cell line (HEK 293) in an autocrine fashion.

scholarly journals Interaction of Bacillus thuringiensis Cry1 and Vip3A Proteins with Spodoptera frugiperda Midgut Binding Sites

2009 ◽  
Vol 75 (7) ◽  
pp. 2236-2237 ◽  
Author(s):  
Janete A. D. Sena ◽  
Carmen Sara Hernández-Rodríguez ◽  
Juan Ferré
Keyword(s):  
Bacillus Thuringiensis ◽  
Spodoptera Frugiperda ◽  
Binding Sites ◽  
Specific Binding ◽  
Binding Assays ◽  
Binding Interactions ◽  
Specific Binding Sites

ABSTRACT Vip3Aa, Vip3Af, Cry1Ab, and Cry1Fa were tested for their toxicities and binding interactions. Vip3A proteins were more toxic than Cry1 proteins. Binding assays showed independent specific binding sites for Cry1 and Vip3A proteins. Cry1Ab and Cry1Fa competed for the same binding sites, whereas Vip3Aa competed for those of Vip3Af.

scholarly journals Analysis of Binding Interactions of Ramipril and Quercetin on Human Serum Albumin: A Novel Method in Affinity Evaluation

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 547
Author(s):  
Zuzana Vaneková ◽  
Lukáš Hubčík ◽  
José Luis Toca-Herrera ◽  
Paul Georg Furtműller ◽  
Pavel Mučaji ◽  
...  
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Accurate Method ◽  
Cd Spectroscopy ◽  
Future Research ◽  
Binding Interactions ◽  
Allosteric Interactions ◽  
Flavonoid Quercetin ◽  
High Concentrations

The aim of this study was to analyze the binding interactions between a common antihypertensive drug (ramipril, R) and the widely distributed plant flavonoid quercetin (Q), in the presence of human serum albumin (HSA). From the observed fluorescence spectra of the (HSA + R) system we can assume that ramipril is also one of the Site 3 ligands—similar to fusidic acid—the binding of which has been proven by RTG crystallography. Our claim is supported by near-UV CD spectroscopy, microscale themophoresis and molecular modeling. The presence of R slightly inhibited the subsequent binding of Q to HSA and, on the contrary, the pre-incubation of HSA with Q caused a stronger binding of R, most likely due to allosteric interactions. At high concentrations, R is also able to displace Q from its binding site. The dissociation constant KD for the binding of R is more than hundredfold larger than for Q, which means that R is a very weak binder to HSA. The knowledge of qualitative and quantitative parameters of R, as well as the methods used in this study, are important for future research into HSA binding. This study shows the importance of implementing other methods for KD determination. Microscale thermophoresis has proved to be a novel, practical and accurate method for KD determination on HSA, especially in cases when fluorescence spectroscopy is unable to produce usable results.

Receptors for insulin-like growth factor-I in plasma membranes isolated from bovine mesenteric arteries

1988 ◽  
Vol 117 (4) ◽  
pp. 428-434 ◽  
Author(s):  
Karin E. Bornfeldt ◽  
Hans J. Arnqvist ◽  
Hans H. Dahlkvist ◽  
Anna Skottner ◽  
Jarl E. S. Wikberg
Keyword(s):  
Plasma Membranes ◽  
Specific Binding ◽  
Polyacrylamide Gel Electrophoresis ◽  
Mesenteric Arteries ◽  
Binding Characteristics ◽  
Factor I ◽  
Reducing Conditions ◽  
Ic50 Value ◽  
Igf I ◽  
High Concentrations

Abstract. Binding of IGF-I to plasma membranes from bovine mesenteric arteries was studied. The maximal specific binding of IGF-I was found to be 7.4 ± 1.7% of total 125I-IGF-I added to the incubation medium. Unlabelled IGF-I displaced 125I-IGF-I with an IC50 value of 0.5 nmol/l and a maximal displacement of 64.2 ± 2.8% of total binding. The potency of insulin to displace 125I-IGF-I was 100–1000-fold lower. Crosslinking of 125I-IGF-I to the receptor with disuccinimidyl suberate, followed by SDS-polyacrylamide gel electrophoresis under reducing conditions showed an IGF-I binding protein with a molecular weight of 146000 Dalton. In summary, we have shown the presence of receptors for IGF-I in plasma membranes isolated from macrovessels. The binding characteristics and the size of the binding unit were found to be similar to those of the IGF-1 receptor found in cultured vascular smooth muscle cells. Furthermore, insulin at high concentrations was found to interact with the IGF-I receptor.

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