scholarly journals Nature and characteristics of the binding of oestradiol-17β to a uterine macromolecular fraction

1968 ◽  
Vol 107 (6) ◽  
pp. 765-774 ◽  
Author(s):  
G. P. Talwar ◽  
M. L. Sopori ◽  
D. K. Biswas ◽  
S. J. Segal
Keyword(s):  
Serum Albumin ◽  
Binding Sites ◽  
Physiological Function ◽  
Receptor Protein ◽  
Binding Properties ◽  
Ph Values ◽  
Binding Function ◽  
High Degree ◽  
Protein Moiety

The binding of oestradiol-17β to two proteins, namely serum albumin and a uterus fraction, was studied in vitro. The former protein has a physiological function in the transport of the hormone and the latter is involved in the selective uptake of the steroid by the target organ. The uterus fraction shows a high degree of stereospecificity for the binding of the steroid. Cortisone, oestradiol-17α and testosterone are bound negligibly and progesterone to a much smaller extent than is oestradiol-17β. This property is in contrast with the wide variety of ligands bound by the serum albumin. The temperature and the presence of the steroid influence markedly the binding properties. Oestradiol binding to the uterus fraction is optimum at 37° and at pH7–8·5. It is markedly decreased at pH values above or below this range, suggesting stringent conformational requirements. The tissue ‘receptor’ protein is a macromolecule with a minimum molecular weight of 100000. The protein moiety is essential for the binding function. The probable concentration of the total binding sites for oestradiol in the ovariectomized-rat uterus cytoplasmic fraction as determined in vitro is about 1mμm at a steroid concentration of 50mμm.

Influence of sex hormone binding globulin and serum albumin on the conversion of androstenedione to testosterone by human erythrocytes

1981 ◽  
Vol 96 (1) ◽  
pp. 136-140 ◽  
Author(s):  
M. Egloff ◽  
N. Savouré ◽  
J. Tardivel-Lacombe ◽  
C. Massart ◽  
M. Nicol ◽  
...  
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Binding Sites ◽  
Sex Hormone ◽  
Human Erythrocytes ◽  
Sex Hormone Binding Globulin ◽  
Total Plasma ◽  
Hormone Binding ◽  
High Binding Affinity

Abstract. The influence of human serum albumin and sex hormone binding globulin (SHBG) on the enzymic conversion of androstenedione to testosterone in human erythrocytes was investigated in vitro. Total plasma and albumin delayed the conversion rate of androstenedione, while SHBG increased it markedly. The effect of SHBG was largely abolished by heating to 60°C for 1 h and by saturating its binding sites by DHT. The effect of both proteins was found to be related to their concentration. It appears that the binding sites of albumin provide a mechanism for retarding androstenedione uptake by the erythrocytes and that the high binding affinity of SHBG for testosterone facilitates the diffusion of this steroid out of the cell and thus, displaces the chemical equilibrium within the cell.

Binding properties of food colorant allura red with human serum albumin in vitro

2014 ◽  
Vol 41 (5) ◽  
pp. 3381-3391 ◽  
Author(s):  
Langhong Wang ◽  
Guowen Zhang ◽  
Yaping Wang
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Binding Properties ◽  
Allura Red ◽  
Food Colorant

Fibrin Binding of Plasminogen Coated Liposomes In Vitro

1996 ◽  
Vol 75 (01) ◽  
pp. 134-139 ◽  
Author(s):  
J L M Heeremans ◽  
P Los ◽  
R Prevost ◽  
D J A Crommelin ◽  
C Kluft
Keyword(s):  
Binding Sites ◽  
In Vitro Model ◽  
Model System ◽  
Binding Properties ◽  
Experimental Conditions ◽  
Binding Rate ◽  
Order Of Magnitude ◽  
Vitro Model

SummaryIn this study, the fibrin binding properties of liposomes containing a number of plasminogen (Pig) molecules on the outside were compared to those of free (non-liposomal) Pig in an in vitro model system. Fibrin monolayer coated 96-wells plates were used, containing fibrin monomer at a density of around 3.4 to 3.9 × 10-4 nmol/cm2. These densities are similar to liposomal Plg-densities, thus allowing multivalent interactions to occur.In the panel of experimental conditions that was chosen, binding of free Pig and liposomes with Pig showed three main differences in characteristics. Firstly, in the fibrin binding of Plg-liposomes not all Pig may be involved, but on the average 40% of the total amount of liposomal Pig. This was shown by lysing the liposomes after binding to the fibrin and estimation of truly bound Pig. With Plg-densities on the liposomes below the fibrin binding sites density, the maximal number of bound Pig molecules remains below the amount of available fibrin binding sites. Secondly, a higher binding rate by at least one order of magnitude was observed for liposomes with Pig compared to free Pig. Thirdly, liposomes with Pig exhibit a fibrin binding affinity which increases with Plg-density, because of the multivalent character of interaction. Liposomal Pig can successfully compete for fibrin binding sites with a 100 fold higher concentration of free Pig.These in vitro findings indicate that in view of avid and rapid fibrin binding, liposomes with attached plasminogen may be suitable for in vivo targeting to fibrin based thrombi.

Binding properties of drospirenone with human serum albumin and lysozyme in vitro

2016 ◽  
Vol 153 ◽  
pp. 612-618 ◽  
Author(s):  
Qing Wang ◽  
Xiangling Ma ◽  
Jiawei He ◽  
Qiaomei Sun ◽  
Yuanzhi Li ◽  
...  
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Binding Properties

Studies on Corticosterone–Receptor Complexes from Mouse Placenta

1974 ◽  
Vol 52 (3) ◽  
pp. 190-195 ◽  
Author(s):  
Ming D. Wong ◽  
A. F. Burton
Keyword(s):  
Binding Sites ◽  
Time Course ◽  
Specific Binding ◽  
Receptor Site ◽  
Binding Properties ◽  
Receptor Complexes ◽  
Specific Binding Sites ◽  
Mouse Placenta ◽  
Vitro Binding

The in vitro binding of radioactive steroids to components of mouse placental nuclei and cytoplasm was investigated using Sephadex or charcoal to remove unbound steroid. Specificity was indicated in competition experiments using excess unlabelled competing steroids. Only the active glucocorticoids formed complexes that could be isolated from the nucleus. The binding properties of the cytoplasmic steroid–receptor complex were studied. From the time course of binding the complex was shown to be more stable at 0° than at 37°, and the distribution of receptors in the cytosol appeared to be homogeneous. The complex was labile to heat and to proteolytic digestion but did not appear to be affected by nucleases or sulfhydryl reagents. Kinetic analysis revealed the presence of high affinity specific binding sites with a dissociation constant of 17.5 nM and a receptor site concentration of 0.26 pmol/mg protein. The corticosterone isolated from nuclear complexes and dexamethasone from cytoplasmic complexes were identified by chromatography and by cocrystallization as the unchanged steroid in each case.

scholarly journals In Vitro Studies on the Relationship Between the Antioxidant Activities of Some Berry Extracts and Their Binding Properties to Serum Albumin

2014 ◽  
Vol 172 (6) ◽  
pp. 2849-2865 ◽  
Author(s):  
Jacek Namiesnik ◽  
Kann Vearasilp ◽  
Alina Nemirovski ◽  
Hanna Leontowicz ◽  
Maria Leontowicz ◽  
...  
Keyword(s):  
Serum Albumin ◽  
Antioxidant Activities ◽  
In Vitro Studies ◽  
Binding Properties ◽  
Berry Extracts ◽  
The Relationship

scholarly journals Ligand-binding properties of proalbumin Christchurch

1980 ◽  
Vol 191 (1) ◽  
pp. 281-283 ◽  
Author(s):  
R G Reed ◽  
T Peters ◽  
S O Brennan ◽  
R W Carrell
Keyword(s):  
Fatty Acids ◽  
Human Serum Albumin ◽  
Ligand Binding ◽  
Serum Albumin ◽  
Human Serum ◽  
Protein Conformation ◽  
Binding Sites ◽  
Bromocresol Green ◽  
Binding Properties ◽  
Normal Albumin

Proalbumin Christchurch, a circulating variant of human serum albumin, is secreted from the liver without cleavage of the hexapeptide situated at the N-terminal end of the peptide chain of proalbumin. We compared ligand-binding properties of proalbumin Christchurch and of normal albumin A from the same individual in order to test the effect of the presence of the hexapeptide. The two albumin forms exhibited similar affinities for palmitate, bilirubin, 8-anilinonaphthalene-1-sulphonate and Bromocresol Green. The patterns of endogenous fatty acids bound to the two forms of albumin were slightly different, although the differences were probably not of physiological significance. From these studies it would appear that the propeptide of proalbumin does not alter the protein conformation in such a way as to alter binding sites for organic anions.

Effect of ageing of human serum albumin in vitro on surface hydrophobicity and binding sites of metronidazole

2011 ◽  
Vol 993 (1-3) ◽  
pp. 477-484 ◽  
Author(s):  
J. Równicka-Zubik ◽  
A. Sułkowska ◽  
M. Dubas ◽  
J. Pożycka ◽  
M. Maciążek-Jurczyk ◽  
...  
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Binding Sites ◽  
Surface Hydrophobicity

scholarly journals Cyclic AMP Receptor Protein-Dependent Repression of Heat-Labile Enterotoxin

2008 ◽  
Vol 77 (2) ◽  
pp. 791-798 ◽  
Author(s):  
Maria D. Bodero ◽  
George P. Munson
Keyword(s):  
Cyclic Amp ◽  
Binding Sites ◽  
The Other ◽  
Receptor Protein ◽  
Heat Stable ◽  
Heat Labile ◽  
Dnase I Footprinting ◽  
Camp Receptor

ABSTRACT Enterotoxigenic Escherichia coli is a major cause of acute diarrheal illness worldwide and is responsible for high infant and child mortality rates in developing nations. Two types of enterotoxins, one heat labile and the other heat stable, are known to cause diarrhea. The expression of soluble heat-labile toxin is subject to catabolite (glucose) activation, and three binding sites for cAMP receptor protein (CRP or CAP) were identified upstream and within the toxin promoter by DNase I footprinting. One CRP operator is centered at −31.5, thus encompassing the promoter's −35 hexamer. Potassium permanganate footprinting revealed that the occupancy of this operator prevents RNA polymerase from forming an open complex in vitro. However, the operator centered at −31.5 is not sufficient for full repression in vivo because the deletion of the other two CRP binding sites partially relieved the CRP-dependent repression of the heat-labile toxin promoter. In contrast to heat-labile toxin, CRP positively regulates the expression of heat-stable toxin. Thus, the conditions for the optimal expression of one enterotoxin limit the expression of the other. Since glucose inhibits the activity of CRP by suppressing the pathogen's synthesis of cyclic AMP (cAMP), the concentration of glucose in the lumen of the small intestine may determine which enterotoxin is maximally expressed. In addition, our results suggest that the host may also modulate enterotoxin expression because cells intoxicated with heat-labile toxin overproduce and release cAMP.

Peptide YY luminal processing and axial heterogeneity of basolateral binding in renal proximal tubules

1991 ◽  
Vol 260 (3) ◽  
pp. F359-F367
Author(s):  
S. Nielsen ◽  
S. P. Sheikh ◽  
M. I. Sheikh ◽  
E. I. Christensen
Keyword(s):  
Binding Sites ◽  
Peptide Yy ◽  
Large Fraction ◽  
Proximal Tubules ◽  
Electron Microscope Autoradiography ◽  
Basolateral Membranes ◽  
Microscope Autoradiography ◽  
Luminal Perfusion ◽  
High Degree

This study investigates the definite location of peptide YY (PYY) binding sites on the basolateral membranes in proximal tubules. S1, S2, and S3 segments were dissected, perfused in vitro, and exposed to [125I-Tyr36]monoiodo-PYY either in the bath fluid or in the perfusate. S1 segments exposed to [125I-Tyr36]PYY in the bath fluid were fixed and prepared for electron microscope autoradiography. The results demonstrated a high degree of axial heterogeneity of basolateral binding of PYY, since only S1 bound PYY, 0.59 +/- 0.09 pg/mm after 15 min; 89.1% could be displaced with unlabeled PYY. PYY was not internalized, 90% of the grains were associated with the basolateral membranes, and no accumulation of grains was observed over the vacuolar apparatus. After luminal perfusion with PYY, 79.3 +/- 7.2% was processed, 61.7 +/- 6.3% was degraded at the brush border, and no tubular accumulation was detected. Thus PYY is not taken up by endocytosis. Unexpectedly, a very large fraction of processed PYY was transported from lumen to bath as trichloroacetic acid (TCA)-precipitable label constituting 41.6 +/- 4.7%. There was no axial heterogeneity in the luminal handling of PYY. In conclusion, this study reveals a high density of PYY binding sites at the basolateral membranes from S1 segments, indicating a selective function of S1 segments on stimulation with PYY. In contrast to other proteins PYY was not internalized from the basolateral membranes.

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