Unfilled nuclear oestrogen receptors in the rat brain and pituitary gland

1982 ◽  
Vol 93 (3) ◽  
pp. 327-338 ◽  
Author(s):  
C. R. Clark ◽  
N. J. MacLusky ◽  
F. Naftolin
Keyword(s):  
Pituitary Gland ◽  
Nuclear Receptor ◽  
Dissociation Constants ◽  
Ovariectomized Rats ◽  
Oestrogen Receptors ◽  
Ligand Specificity ◽  
Cell Nuclei ◽  
Receptor Sites ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation

This study describes the presence of a population of oestrogen receptors in cell nuclei from the pituitary gland and brain of untreated and oestradiol-treated ovariectomized rats. The receptors behaved as if they were not occupied by oestradiol. These 'unfilled' oestrogen receptors could be distinguished from occupied nuclear receptor sites on the basis of their ability to bind [3H]oestradiol at low temperatures (0–4 °C). Occupied receptors bound labelled [3H]oestradiol only under exchange conditions at an increased temperature (25 °C). Unfilled and occupied nuclear receptors were physicochemically similar in terms of sedimentation coefficients in sucrose density gradients containing 0·4 m-KC1 (4–5S), equilibrium dissociation constants for reaction with [3H]oestradiol (0·2–0·6 nmol/l) and ligand specificity. In ovariectomized rats, unfilled receptors constituted more than 75 % of the total nuclear receptor population. One hour after i.v. treatment with oestradiol (3·6 μg/kg), both total and unfilled nuclear receptor concentrations increased and then subsequently declined over the next 12 h. The increase in unfilled sites was, however, proportionately less than that occurring in the filled component; at 1 h after oestradiol injection unfilled sites constituted less than 20% of the receptors present in brain and pituitary cell nuclei. The physiological significance of unfilled nuclear oestrogen receptors remains unknown. The observations that they exist in various oestrogen target tissues and that their levels are influenced by oestradiol treatment suggest a possible role for these receptors in the mechanism of oestrogen action.

Altered plasma catecholamines and numbers of α- and β-adrenergic receptors in platelets and leucocytes in hyperthyroid patients normalized under antithyroid treatment

1985 ◽  
Vol 110 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Dieter Ratge ◽  
Sabine Hansel-Bessey ◽  
Hermann Wisser
Keyword(s):  
Dissociation Constants ◽  
Plasma Catecholamines ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Plasma Norepinephrine ◽  
Thyroid State ◽  
Antithyroid Treatment ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation ◽  
Hyperthyroid Patients

Abstract. We measured plasma catecholamines, α- and β-adrenoreceptor numbers and the accumulation of cyclic adenosine monophosphate (cAMP) in the unstimulated state and in response to 10 μmol/l (-) isoproterenol in blood cells from 29 euthyroid controls and from 18 patients with spontaneous hyperthyroidism. In the thyrotoxic patients plasma norepinephrine (1.14 ± 0.5 nmol/l) and epinephrine (0.3 ±0.14 nmol/l) were significantly decreased compared with plasma norepinephrine (1.87 ± 0.7 nmol) and epinephrine (0.41 ± 0.19 nmol/l) in the controls (P < 0.01 and P < 0.05, respectively) and the values obtained in subjects rendered euthyroid by antithyroid treatment (P < 0.001, respectively). α-adrenoceptor density in platelet membranes obtained from patients in the hyperthyroid state (114 ± 38 sites per cell) was significantly decreased when compared with controls (159 ± 48 sites per cell, P < 0.01) and the values from patients under effective antithyroid treatment (136 ± 35 sites per cell, P < 0.01). On the contrary, a significant increase in β-adrenoceptor density in mononuclear leucocyte (MNL) membranes was found in hyperthyroid patients (1751 ± 237 sites/cell) when compared with controls (1510 ± 351 sites/cell, P < 0.05) and the same patients following antithyroid treatment (1455 ± 260 sites/cell, P < 0.001). The equilibrium dissociation constants (KD) did not change in hyperthyroidism. Basal cAMP concentrations in MNL were higher in untreated thyrotoxicosis (45 ± 18 pmol/106 cells/10 min) than in patients in the euthyroid state (35 ± 9 pmol/106 cells/10 min, P < 0.05). Our data support the hypothesis that the balance of α- and β-adrenoceptors depends on the thyroid state. However, before the reputed catecholamine supersensitivity in hyperthyroid man can be accepted, the relationship between alterations in adrenoceptors and the biological responsiveness to catecholamines has to be demonstrated in different human tissues.

scholarly journals Circular dichroism determination of class I MHC-peptide equilibrium dissociation constants

1997 ◽  
Vol 6 (8) ◽  
pp. 1771-1773 ◽  
Author(s):  
Chantal S. Morgan ◽  
James M. Holton ◽  
Barry D. Olafson ◽  
Pamela J. Bjorkman ◽  
Stephen L. Mayo
Keyword(s):  
Circular Dichroism ◽  
Dissociation Constants ◽  
Class I ◽  
Class I Mhc ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation ◽  
Circular Dichroïsm

Preparation and Characterization of Paclitaxel Imprinted Silica Nanoparticles

2011 ◽  
Vol 399-401 ◽  
pp. 1894-1897
Author(s):  
Jian Hua Li ◽  
Zong Jian Zheng ◽  
Shao Ping Fu ◽  
Jing Bo Zhu
Keyword(s):  
Silica Nanoparticles ◽  
Dissociation Constants ◽  
Sol Gel ◽  
Scatchard Analysis ◽  
Binding Properties ◽  
Imprinted Polymers ◽  
Sol Gel Process ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation

Highly selective molecularly imprinted layer-coated silica nanoparticles for paclitaxel were synthesized by molecular imprinting technique with a sol–gel process on the supporter of silica nanoparticles. The morphology of the obtained polymers was characterized by scanning electron microscopy (SEM). The binding properties of the imprinted polymers were evaluated through the equilibrium rebinding experiments. Scatchard analysis revealed that two classes of binding sites were formed in the imprinted polymers with equilibrium dissociation constants of 0.0509 g•L-1and 0.0094 g•L-1, respectively. Paclitaxel and its analogue were employed for selectivity tests. The results indicated that the imprinted polymers exhibited good selectivity and specificity toward paclitaxel.

Adrenal medullary regulation of rat renal cortical adrenergic receptors

1987 ◽  
Vol 253 (5) ◽  
pp. F1063-F1067
Author(s):  
P. R. Sundaresan ◽  
M. M. Guarnaccia ◽  
J. L. Izzo
Keyword(s):  
Adrenal Medulla ◽  
Adrenergic Receptors ◽  
Dissociation Constants ◽  
Specific Binding ◽  
Physiological State ◽  
Plasma Corticosterone ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation

The role of the adrenal medulla in the regulation of renal cortical adrenergic receptors was investigated in renal cortical particulate fractions from control rats and rats 6 wk after adrenal demedullation. The specific binding of [3H]prazosin, [3H]rauwolscine, and [125I]iodocyanopindolol were used to quantitate alpha 1-, alpha 2-, and beta-adrenergic receptors, respectively. Adrenal demedullation increased the concentration of all three groups of renal adrenergic receptors; maximal number of binding sites (Bmax, per milligram membrane protein) for alpha 1-, and alpha 2-, and beta-adrenergic receptors were increased by 22, 18.5, and 25%, respectively (P less than 0.05 for each). No differences were found in the equilibrium dissociation constants (KD) for any of the radioligands. Plasma corticosterone and plasma and renal norepinephrine levels were unchanged, whereas plasma epinephrine was decreased 72% by adrenal demedullation (P less than 0.01); renal cortical epinephrine was not detectable in control or demedullated animals. Our results suggest that, in the physiological state, the adrenal medulla modulates the number of renal cortical adrenergic receptors, presumably through the actions of a circulating factor such as epinephrine.

Further studies on the corticosteroid-receptor system of the nasal gland of the domestic duck (Anas platyrhynchos)

1983 ◽  
Vol 61 (7) ◽  
pp. 731-743 ◽  
Author(s):  
Thomas Sandor ◽  
Afzal Z. Mehdi ◽  
John A. DiBattista
Keyword(s):  
Ammonium Sulfate ◽  
Reaction Temperature ◽  
Rate Constants ◽  
Binding Sites ◽  
Dissociation Constants ◽  
Similar Data ◽  
Nuclear Binding ◽  
Ammonium Sulfate Precipitate ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation

The interaction of tritiated corticosterone with the nasal gland corticosterone receptor was investigated. Kinetic studies have shown that the association of [3H]corticosterone–receptor followed second-order reaction kinetics and the dissociation of the ligand from the receptor became "pseudo" first order in the presence of large excess of radioinert steroids at 0, 15, 25, and 35 °C. Similar data were obtained with an ammonium sulfate precipitate of the cytosol. Dissociation rate constants varied from 10−5 to 10−3 s−1 and the association rate constants varied from 0.5 × 104 to 3.8 × 105 M−1∙s−1, depending on the reaction temperature and the cytoplasmic receptor preparation. Equilibrium dissociation constants were in 10−8–10−9 M range. Equilibrium dissociation constants, calculated from kinetic data (kd/ka), showed a marked temperature dependence, while those obtained by saturation analysis varied much less with the reaction temperature. Data obtained in these experiments were used to calculate some thermodynamic parameters of the binding of corticosterone to the cytoplasmic receptor. The enthalpy of dissociation was 101.5 and 79.4 kJ∙mol−1 and the entropy of dissociation was 200 and 280 J∙mol−1∙degree−1 for the crude cytoplasmic receptor and the ammonium sulfate precipitate, respectively. From the equilibrium dissociation constants, the enthalpy and entropy of the equilibrium binding was calculated. Polynomial fitting of Ka values versus 1/T yielded enthalpy (ΔH) values from −0.9 to −88.8 kJ∙mol−1, depending on the nature of the receptor preparation. Entropy values were negative for kinetically derived equilibrium association constants from the crude cytosol at all temperatures and for 0 and 15 °C for the precipitate. Entropy values were positive for Ka values obtained from kinetic rates at 25 and 35 °C and for Ka's calculated from saturation analysis. Further experiments with the precipitate confirmed our previous contention that the nasal gland cytoplasmic corticosterone receptor metabolized the bound ligand to 11-dehydrocorticosterone, though the receptor preparation was corticosterone specific. The following hydrodynamic parameters were obtained on the binding macromolecule: molecular weight, 316 000; s20,w, 8.0; Stokes radius (rs), 77.3 Å (1 Å = 0.1 nm); total frictional ratio (f/f0), 1.71. The labeled receptor preparation translocated to homologous nuclear binding sites following heat activation and, at the nuclear binding sites, the ligand was almost exclusively in its oxidized form. Measurement of the nuclear steroid–receptor complex by exchange assay with [3H]corticosterone confirmed the presence of nuclear binding sites. From these studies, it was concluded that the nasal gland of the duck contains specific, glucocorticoid-type corticosterone receptors and that the effector steroid is probably 11-dehydrocorticosterone or a critical mixture of these two steroids, with the oxidized form predominating.

Characterization and Evaluation of Binding Properties of Salvianolic Acid a Imprinted Polymers Prepared by Precipitation Polymerization

2011 ◽  
Vol 239-242 ◽  
pp. 2423-2426
Author(s):  
Lin Min Zhu ◽  
Shao Ping Fu ◽  
Lin Ying Li ◽  
Jing Bo Zhu
Keyword(s):  
Dissociation Constants ◽  
Precipitation Polymerization ◽  
Scatchard Analysis ◽  
Template Molecule ◽  
Binding Properties ◽  
Imprinted Polymers ◽  
Salvianolic Acid ◽  
Salvianolic Acid A ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation

Molecularly imprinted polymers (MIPs) were synthesized by precipitation polymerization using salvianolic acid A (Sal A), acrylamide (AA), ethylene glycol dimethacrylate (EGDMA) and acetonitrile as template molecule, functional monomer, cross-linker and solvent, respectively. The morphology of the obtained polymers was characterized by scanning electron microscopy (SEM). The effect of different polymerization conditions (solvent volume, solvent and template amount) on the size and shape of particles was investigated. The binding properties of the imprinted polymers were evaluated through the equilibrium rebinding experiments. Scatchard analysis revealed that two classes of binding sites were formed in the imprinted polymers with equilibrium dissociation constants of 0.33 μmol·mL-1and 0.07 μmol·mL-1, respectively. Besides Sal A, two structurally related compounds, protocatechuic aldehyde (Pra) and salvianolic acid B (Sal B), were employed for molecular selectivity tests. The results indicated that the imprinted polymers exhibited good selectivity and specificity toward Sal A.

Correlation of pheromone-binding protein–ligand equilibrium dissociation constants with electroantennogram response patterns

2018 ◽  
Vol 96 (2) ◽  
pp. 168-177 ◽  
Author(s):  
Mailyn Terrado ◽  
Yang Yu ◽  
Erika Plettner
Keyword(s):  
Gypsy Moth ◽  
Dissociation Constants ◽  
Odorant Receptor ◽  
Receptor Activation ◽  
Water Soluble ◽  
Response Patterns ◽  
High Concentration ◽  
Lag Times ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation

Pheromone-binding proteins (PBPs) are water-soluble proteins found at high concentration in the lymph fluid of pheromone-sensing hairs on insect antennae. PBPs could function as pheromone transporters, ferrying the hydrophobic odorants to their cognate odorant receptors. However, it is also possible for these proteins to bind the odorants near the dendritic membrane of pheromone-sensing neurons and, therefore, function as scavengers. The two functions are not mutually exclusive. In this paper, the transporter and (or) scavenger roles of PBPs in pheromone perception were investigated using the pheromone of the gypsy moth (7R, 8S)-epoxy-2-methyloctadecane and analogues with heteroatom (O or S) substitutions in the hydrocarbon chain. PBP–ligand equilibrium dissociation constants (Kd) were correlated with electroantennogram (EAG) response patterns of male gypsy moth antennae to the pheromone, its enantiomer, and their respective analogues. EAG measures the potential drop across the antenna due to odorant receptor activation and subsequent ion channel opening. Three quantifiable properties of the EAG responses were used: lag times from stimulus to response onset, depolarization rates (rate of receptor activation), and repolarization rates (rate of receptor deactivation). Negative correlations were observed between Kd and lag times and between Kd and repolarization rates. Positive correlations were seen with Kd against depolarization rates. The inverse relationship of Kd constants with lag times and the direct relationship with depolarization rates strongly supports transporter function of PBPs. Interestingly, the inverse correlation of Kd constants with repolarization rates suggests a scavenger effect. These results indicate that PBP affects odorant receptor activity through both odorant transport and scavenger functions. Through differences in ligand binding affinities, PBPs influence pheromone availability for receptor activation.

Sign in / Sign up

Export Citation Format

Share Document