Search results for "Dissociation constant"
showing 10 items of 55 documents
A muscarinic receptor different from the M1, M2, M3 and M4 subtypes mediates the contraction of the rabbit iris sphincter
1992
In order to analyse the subtype of muscarinic receptors involved in the methacholine-induced contraction of the rabbit iris sphincter we have determined equilibrium dissociation constants (KB) of various antagonists in the sphincter muscle. The values were compared with those observed at M1 (rabbit vas deferens), M2 (heteroreceptors in rat iris) and M3 receptors (guinea-pig ileum), or at the muscarinic receptors in the guinea-pig uterus. The methacholine-induced contraction of the uterus from immature guinea-pigs was competitively antagonized by pirenzepine (6.64, -log KB), 4-DAMP (8.39), hexahydrodifenidol (HHD; 7.00 for the (R)- and 5.40 for the (S)-enantiomer), p-fluoro-hexahydrosiladife…
Aptamer-embedded DNA origami cage for detecting (glycated) hemoglobin with a surface plasmon resonance sensor
2020
DNA origami-based cages functionalized with aptamer motifs, were used to detect hemoglobin and glycated hemoglobin. The binding between the cages and hemoglobin was monitored using a surface plasmon resonance (SPR) sensor. One DNA strand in the nano-cage was replaced with an aptamer that demonstrated a high affinity to hemoglobin (Hb) or glycated hemoglobin (gHb). Three types of the DNA nano-cages designed to fit the size and shape of hemoglobin were evaluated: one without an aptamer, one with the Hb-affinity aptamer (HA) and one with the gHb-affinity aptamer (GHA). Both DNA nano-cages embedded with HA and GHA showed significantly more stable binding with Hb and gHb by 5 and 9 times, respec…
Electrochemical detection of the 2-isobutyl-3-methoxypyrazine model odorant based on odorant-binding proteins: The proof of concept
2014
Abstract We developed an electrochemical assay for the detection of odorant molecules based on a rat odorant-binding protein (rOBP3). We demonstrated that rOBP3 cavity binds 2-methyl-1,4-naphtoquinone (MNQ), an electrochemical probe, as depicted from the decrease of its electrochemical signal, and deduced the dissociation constant, Kd MNQ = 0.5(± 0.2) μM. The amount of MNQ displaced from rOBP3 by 2-isobutyl-3-methoxypyrazine (IBMP), a model odorant molecule, was measured using square-wave voltammetry. The release of MNQ by competition led to an increase of the electrochemical response. In addition, this method allowed determination of the dissociation constant of rOBP3 for IBMP, Kd IBMP =…
Silicic acid competes for dimethylarsinic acid (DMA) immobilization by the iron hydroxide plaque mineral goethite.
2015
Abstract A surface complexation modeling approach was used to extend the knowledge about processes that affect the availability of dimethylarsinic acid (DMA) in the soil rhizosphere in presence of a strong sorbent, e.g., Fe plaques on rice roots. Published spectroscopic and molecular modeling information suggest for the organoarsenical agent to form bidentate-binuclear inner-sphere surface complexes with Fe hydroxides similar to the inorganic As oxyanions. However, since also the ubiquitous silicic acid oxyanion form the same bidentate binuclear surface complexes, our hypothesis was that it may have an effect on the adsorption of DMA by Fe hydroxides in soil. Our experimental batch equilibr…
Enhanced Acid Dissociation at the Solid/Liquid Interface
2019
In this chapter we review some recent results from first principles molecular dynamics simulations which show how molecular properties, such as proton dissociation, can be influenced upon adsorption at a solid/liquid interface. In particular, we discuss in details the increased acidity of pyruvic acid at the quartz /water interface, which is of relevance for the chemistry of the atmosphere. Our simulations unveil the special role of the microsolvation at interface, as well as the role of the silanols in stabliziing the deprotonated form of the acid. The enhanced acidity at the hydrophilic quartz/water interface is at odd with what typically found at the water/air interface where acidity is …
MCC1019, a selective inhibitor of the Polo-box domain of Polo-like kinase 1 as novel, potent anticancer candidate
2019
Polo-like kinase (PLK1) has been identified as a potential target for cancer treatment. Although a number of small molecules have been investigated as PLK1 inhibitors, many of which showed limited selectivity. PLK1 harbors a regulatory domain, the Polo box domain (PBD), which has a key regulatory function for kinase activity and substrate recognition. We report on 3-bromomethyl-benzofuran-2-carboxylic acid ethyl ester (designated: MCC1019) as selective PLK1 inhibitor targeting PLK1 PBD. Cytotoxicity and fluorescence polarization-based screening were applied to a library of 1162 drug-like compounds to identify potential inhibitors of PLK1 PBD. The activity of compound MC1019 against the PLK1…
Ah receptor mediating induction of cytochrome P450IA1 in a novel continuous human liver cell line (Mz-Hep-1)
1991
Abstract The Ah receptor regulates induction of cytochrome P450IA1 and mediates certain toxicities of polyhalogenated aromatics such as 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD). It has been characterized previously in continuous cell lines, notably the mouse hepatoma line Hepa 1, the human squamous cell carcinoma line A431, and the human liver cell line Hep G2. The present work extends our knowledge of the Ah receptor in continuous human liver cell lines. Ah receptor can be detected in Mz-Hep-1, a hepatitis B virus-negative cell line derived from a Thorotrast-induced hepatocellular carcinoma. The mean concentration of Ah receptor in Mz-Hep-1 cells was 341 ± 22 fmol/mg cytosol protein (m…
l-Glutamate receptor binding in bovine retina
1982
Using a centrifugation technique saturable specific [ 3 H]glutamate binding in bovine retina could be demonstrated. Scatchard analysis revealed only one population of binding sites with a dissociation constant of about 3 μ m and a maximal number of binding sites of about 0·2 pmol/mg retinal protein. Several glutamic acid analogues inhibit specific [ 3 H]glutamate binding in bovine retina with half-maximal inhibitory concentrations similar to those reported in other areas of the CNS. Specific [ 3 H]glutamate binding and sodium dependent synaptosomal uptake of glutamate are largely concentrated in the P2 fraction of bovine retina homogenates consisting of conventionally sized synaptosomes. Th…
(o-Hydroxyphenyl)methylphosphonic Acids: Spectrophotometric determination of their pKavalues and of the deprotonation sequence
1993
UV/VIS Absorption spectra of nitrosubsituted (o-hydroxyphenyl)methylphosphonic acids (o-(phosphonomethyl)phenols) were measured as a function of pH at 25° in 0.1M NaClo4 solutions. Computational treatment of the whole set of optical density data between 200 and 500 nm resulted in the determination of the dissociation constants of these polyacids and also of the individual electronic spectra of all the species involved in the deprotonation sequence. The spectral behavior gives information on the structure of the anions formed and consequently the order of the subsequent deprotonation steps could be deduced. For the (2-hydroxy-3-nitro(or 5-nitro)phenyl)methylphosphonic acid and the 2-hydroxy-…
Use of Catalyst in a 3D-QSAR Study of the Interactions between Flavor Compounds and β-Lactoglobulin
2003
This paper reports a 3D-QSAR study using Catalyst software to explain the nature of interactions between flavor compounds and beta-lactoglobulin. A set of 35 compounds, for which dissociation constants were previously determined by affinity chromatography, was chosen. The set was divided into three subsets. An automated hypothesis generation, using HypoGen software, produced a model that made a valuable estimation of affinity and provided an explanation for the lack of correlation previously observed between the hydrophobicity of terpenes and the affinity for the protein. On the basis of these results, it appears that aroma binding to beta-lactoglobulin is caused by both hydrophobic interac…