scholarly journals The binding of calcium and yttrium ions to a glycoprotein from bovine cortical bone

1967 ◽  
Vol 105 (3) ◽  
pp. 1177-1185 ◽  
Author(s):  
P A Williams ◽  
A. R. Peacocke
Keyword(s):  
Cortical Bone ◽  
Binding Sites ◽  
Association Constant ◽  
Chondroitin Sulphate ◽  
Bone Sialoprotein ◽  
Carboxyl Groups ◽  
Similar Extent ◽  
Strong Electrostatic Interaction ◽  
Titration Curves ◽  
Number Of Binding Sites

The binding of Ca2+ and Y3+ to an acidic glycoprotein from bovine cortical bone, bone sialoprotein, was determined from the titration curves at I 0·2 in the presence and absence of the cations. The binding of Y3+ was greater than that of Ca2+. The value for the association constant, k, for the interaction with Y3+ increased with pH, from log k 2·93 at pH3·4 to log k 3·50 at pH4·4, and the number of binding sites/mol. increased from 4·6 at pH3·4 to 9·1 at pH4·4. It is proposed that the binding site consists of three carboxyl groups, but it is likely that the binding is a strong electrostatic interaction rather than a co-ordination linkage. A chondroitin sulphate–protein complex also extracted from bovine cortical bone interacted with Y3+ and Ca2+ to a similar extent as did bone sialoprotein. It is suggested that these materials are present in bone at the resting and resorbing surfaces and that they contribute to the deposition of yttrium, americium and plutonium at these sites.

scholarly journals The binding of hydrogen ions to an acidic glycoprotein from bovine cortical bone

1967 ◽  
Vol 105 (3) ◽  
pp. 1171-1175 ◽  
Author(s):  
A. R. Peacocke ◽  
P A Williams
Keyword(s):  
Sodium Chloride ◽  
Glutamic Acid ◽  
Titration Curve ◽  
Analytical Data ◽  
Total Content ◽  
Bone Sialoprotein ◽  
Model Systems ◽  
Carboxyl Groups ◽  
Hydrogen Ions ◽  
Titration Curves

The H+ ion dissociation of bone sialoprotein in 0·2m-sodium chloride at 25° was studied. The total content of carboxyl groups available for titration was calculated by comparing the titration curve with the titration curves of three model systems and by the use of analytical data. This comparison showed that 7·0 carboxyl groups/mol. do not participate in the titration, and it is proposed that these are aspartic acid or glutamic acid carboxyl groups present as amides; this is also indicated by titration of the sialoprotein after acid hydrolysis. The titration of carboxyl groups was found to agree well with the Linderstrøm-Lang equation for spherical macroions.

scholarly journals Studies on the protein-bound chondroitin sulphate of bovine cortical bone

1968 ◽  
Vol 107 (1) ◽  
pp. 41-49 ◽  
Author(s):  
G. M. Herring
Keyword(s):  
Ion Exchange ◽  
Cortical Bone ◽  
Chondroitin Sulphate ◽  
Bone Sialoprotein ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Mild Conditions ◽  
The Third ◽  
Apparent Homogeneity

A fraction containing chondroitin sulphate, isolated from bovine cortical bone under mild conditions, was separated by ion-exchange chromatography into three fractions with apparent homogeneity on electrophoresis and ultracentrifugation. Two of these appeared to consist of chondroitin sulphate bound to a glycoprotein ‘core’ that had similarities to the bone sialoprotein described previously. The differences in composition of the two fractions were considered to be due to variation in the number or lengths of the polysaccharide chains. The presence of xylose and the alkali-lability of the bond between protein and polysaccharide suggested the presence of a xylosylserine linkage. The third fraction had the properties of a relatively pure chondroitin sulphate which contained a small amount of peptide. These fractions differed considerably from the protein–polysaccharide complexes of epiphysial and other cartilages, and their relevance to the possible role of glycosaminoglycans is discussed.

The interaction of sialidase-treated hCG with ovarian cellular membranes

1981 ◽  
Vol 97 (2) ◽  
pp. 270-280 ◽  
Author(s):  
E. C. Brand ◽  
J. Odink ◽  
G. Klok ◽  
E. V. van Hall
Keyword(s):  
Binding Sites ◽  
Association Constant ◽  
Apparent Difference ◽  
Receptor Complexes ◽  
Number Of Binding Sites ◽  
Biological Potency ◽  
The Difference ◽  
The Stability ◽  
Dissociation Curves ◽  
Hcg Receptor

Abstract. The potency of human chorionic gonadotrophin (hCG) in competition for binding to a gonadal membrane fraction is remarkably enhanced by sialidase treatment. The present study was undertaken to investigate the specificity and characteristics of the binding of sialidase-treated hCG (asialo-hCG) in a particulate hCG-binding system from luteinized rat ovaries. The competitive potency of asialo-hCG relative to hCG was 2.5, irrespective of whether [125I]hCG or [125I]asialo-hCG was used for tracer. This was due to a 2.1 times higher equilibrium association constant for asialo-hCG, whereas the estimated number of binding sites did not differ. There was no apparent difference in the stability of hCG and asialo-hCG, or in the stability of the respective hormone-receptor complexes. The effect of variation of the incubation conditions on the binding of both tracers was similar. In accordance with the difference in the equilibrium association constant, the association velocity of asialo-hCG was more than double that of hCG. With all of the tracers used the dissociation curves were biphasic, the size of the initial fast-dissociating fraction being inversely related to the pre-incubation time. Under identical conditions, the fast-dissociating fraction was smaller for the [125I]asialo-hCG complex than for the [125I]hCG complex. The dissociation velocities of these fractions appeared to be similar. The results indicate that asialo-hCG binds to the hCG receptor in a way similar to the binding of the unmodified hormone, but with a higher affinity. The smaller size of the fast-dissociation form of the asialo-hCG-receptor complex may be related to the lower biological potency of the hormone derivative.

CHANGES IN OESTRADIOL-17β BINDING IN THE HYPOTHALAMI AND PITUITARY GLANDS OF PERSISTENTLY INFERTILE EWES PREVIOUSLY EXPOSED TO OESTROGENIC SUBTERRANEAN CLOVER: EVIDENCE OF ALTERATIONS TO OESTRADIOL RECEPTORS

1978 ◽  
Vol 78 (2) ◽  
pp. 171-177 ◽  
Author(s):  
B. Y. TANG ◽  
N. R. ADAMS
Keyword(s):  
Binding Sites ◽  
Association Constant ◽  
Feedback Regulation ◽  
Subterranean Clover ◽  
Pituitary Glands ◽  
Number Of Binding Sites ◽  
And Control ◽  
Apparent Association

SUMMARY The binding of [3H]oestradiol-17β to the hypothalamus and pituitary gland of cloveraffected permanently infertile and control ovariectomized ewes was compared in vivo and in vitro. When [3H]oestradiol-17β was infused into the carotid artery (10 ng/min), the total homogenate and the nuclear and protamine-precipitable cytosol fractions of hypothalami and pituitary glands from clover-affected ewes bound significantly more [3H]oestradiol than those of the controls. Cytoplasmic oestradiol-17β receptors from the pituitary glands of clover-affected ewes showed a significantly lower apparent association constant and a higher number of binding sites/mg protein in vitro. It is suggested that the hypothalami and pituitary glands of ewes made permanently infertile by oestrogenic clover are less sensitive to feedback regulation of oestradiol-17β at physiological levels.

Zinc transport in the haemolymph of Carcinus maenas (Crustacea: Decapoda)

1984 ◽  
Vol 64 (4) ◽  
pp. 801-807 ◽  
Author(s):  
Paolo Zatta
Keyword(s):  
Binding Sites ◽  
Association Constant ◽  
Carcinus Maenas ◽  
Zinc Ions ◽  
Zinc Transport ◽  
Copper Protein ◽  
Number Of Binding Sites

In Carcinus maenas haemolymph, zinc is almost entirely bound to the respiratory pigment, which is the copper-protein haemocyanin (Hc). Zinc ions are loosely bound, as indicated by the low value of the association constant (k = 1.7 × 105 M-1 at pH = 8.0). The number of binding sites N is equal to 4 per minimal functional subunit (75000 Dalton). No co-operativity has been found between the different metal sites. Data reported in this paper support the hypothesis that haemocyanin can act as metal carrier in the haemolymph of C. maenas.

Interaction of ryanodine with the calcium releasing system of sarcoplasmic reticulum vesicles

1988 ◽  
Vol 43 (1-2) ◽  
pp. 140-148 ◽  
Author(s):  
Wilhelm Hasselbach ◽  
Andrea Migala
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Binding Sites ◽  
Time Course ◽  
Calcium Release ◽  
Reaction Times ◽  
Titration Curves ◽  
Equilibrium Data ◽  
Number Of Binding Sites ◽  
Reported Data ◽  
Calcium Induced Calcium Release

Heavy sarcoplasmic reticulum vesicles were reacted with ryanodine in 0.6 ᴍKCl 0.3 ᴍ sucrose at pH 6.3 and pH 7.0 at 20 °C. The inhibition of caffeine induced calcium release from actively loaded vesicles by ryanodine was applied to monitor time course and attainment of equilibrium of the interaction of ryanodine with its receptors in the vesicular membranes. At ryanodine concentrations rising from 0.1-100 μᴍ, the logarithms of the release amplitudes linearly decline with time. The dependence of the inactivation reaction on the concentration of ryanodine did not saturate in the applicable concentration range. The reaction halflife times are concentration dependent. At pH 7.0, the half times decline from 100 to 10 s when the ryanodine concentration is raised from 0.1 to 1 μᴍ. At pH 6.3 a corresponding decline occurs between 3 μᴍ and 100 μᴍ. The marked dependence of the inactivation reaction on medium pH requires reaction times of one and five hours at pH 7.0 and 6.3, respectively for the attainment of reaction equilibrium at low ryanodine concentrations. The dependence of the amplitude of calcium release on the concentration of added ryanodine has been evaluated as proposed by Gutfreund (Enzymes: Physical Principles, p. 71, Wiley-Interscience, London 1972) for the preparation’s affinity for ryanodine and its number of binding sites. At pH 7.0, preparations appear to contain only 0.7 pmol sites per mg protein having an affinity for ryanodine of 0.33 nᴍ-1. The titration curves for caffeine induced calcium release, initial calcium uptake and final calcium level are identical, indicating that the three functions are controlled by the same receptor. Calcium induced calcium release, however, is only partially and differently affected by the occupancy of the high affinity ryanodine binding sites. The kinetic and equilibrium data for the effects of ryanodine were combined and analyzed on account of a two step reaction sequence. The corresponding dissociation and rate constants were evaluated and combined with reported data of [3H]ryanodine binding (Pessah et al., J. Biol. Chem. 261, 8643-8648 (1986))

The Estimation of the Number of Binding Sites for Antibody on Antigen Molecules with Reference to Factor VIII and its Antibody

1976 ◽  
Vol 35 (02) ◽  
pp. 274-288 ◽  
Author(s):  
Judith Pool ◽  
Rosemary Biggs ◽  
R. G Miller
Keyword(s):  
Factor Viii ◽  
Binding Sites ◽  
Theoretical Basis ◽  
Human Antibody ◽  
Rabbit Antibody ◽  
Number Of Binding Sites ◽  
Theoretical Considerations

SummaryThe theoretical basis for determining the number of antibody sites on antigen molecules is examined. The theoretical considerations are applied to factor VIII molecules. Examples based on data available at the Oxford Haemophilia Centre are calculated to illustrate the approach. It is concluded that there are few sites on each factor VIII molecule for human antibody. The three antibodies for which reasonable data were available suggest 1–3 sites for human antibody. The data for rabbit antibody suggest 5–6 sites per factor VIII molecule.

Abnormal Platelet Serotonin Uptake and Binding Sites in Myeloproliferative Disorders

1984 ◽  
Vol 51 (03) ◽  
pp. 349-353 ◽  
Author(s):  
C Caranobe ◽  
P Sié ◽  
F Fernandez ◽  
J Pris ◽  
S Moatti ◽  
...  
Keyword(s):  
Binding Sites ◽  
High Capacity ◽  
Specific Inhibitor ◽  
Myeloproliferative Disorders ◽  
Normal Subjects ◽  
Binding Data ◽  
Full Explanation ◽  
Number Of Binding Sites ◽  
5 Ht Uptake ◽  
Kinetics Of

SummaryA simultaneous investigation of the kinetics of serotonin (5 HT) uptake and of binding sites was carried out in the platelets of normal subjects and of 10 patients affected with various types of myeloproliferative disorders (MD). The 5 HT uptake was analysed according to the Lineweaver-Burk and the Eadie-Hofstee methods. With the two methods, the patient’s platelets exhibited a dramatic reduction of the Vi max and of the Km; in some patients the Eadie-Hofstee analysis revealed that a passive diffusion phenomenon is superimposed on the active 5 HT uptake at least for the higher concentration used. The binding data were analysed with the Scatchard method. Two classes of binding sites (high affinity - low capacity, low affinity - high capacity) were found in normal subjects and patients. Pharmacological studies with imipramine, a specific inhibitor of 5 HT uptake, suggested that both the sites are involved in 5 HT uptake. The number of both binding sites was significantly decreased in patient’s platelets while the affinity constants of these binding sites were not significantly reduced in comparison with those of the control subjects. No correlations were found between Vi max, Km and the number of binding sites. These results suggest that a reduction in the number of platelet membrane acceptors for 5 HT commonly occurs in myeloproliferative disorders but does not provide a full explanation of the uptake defect.

Effects of cations on binding of human choriogonadotropin

1988 ◽  
Vol 66 (12) ◽  
pp. 1258-1264
Author(s):  
Patrick J. McIlroy
Keyword(s):  
Binding Sites ◽  
Regulatory Protein ◽  
Guanine Nucleotides ◽  
Guanine Nucleotide ◽  
Human Choriogonadotropin ◽  
Receptor Sites ◽  
Number Of Binding Sites ◽  
Receptor Number ◽  
Guanine Nucleotide Regulatory Protein ◽  
Low Ionic Strength

The effect of various salts on the binding of human choriogonadotropin to rat luteal membranes has been examined. Increasing salt concentrations had biphasic effects, initially increasing binding, then decreasing it. With NaCl, these effects were on both the affinity and the number of receptor sites. The affinity increased with increasing NaCl concentrations, to a maximum at 40 mM, and then decreased. Above 40 mM NaCl, the number of binding sites increased. NaCl also altered the effects of Mg2+ and guanyl nucleotides. At low ionic strength, Mg2+ was necessary to observe binding. Guanine nucleotides modulated this binding by decreasing the affinity. At 40 mM NaCl, Mg2+ increased receptor number without altering affinity. Guanyl nucleotides modulated this binding by reducing the number of sites to that observed in the absence of Mg2+. At 150 mM NaCl, Mg2+ and guanine nucleotides had no effect. The results suggest the presence of two pools of human choriogonadotropin receptor in rat corpus luteum, one coupled to the guanine nucleotide regulatory protein (Ns) and being Mg2+ dependent and guanine nucleotide sensitive, and the other not coupled to Ns and being Mg2+ independent and guanine nucleotide insensitive.

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