scholarly journals Characterization of pancreatic b-cell receptors binding sulfanilamides under conditions of experimental diabetes mellitus

1996 ◽  
Vol 42 (5) ◽  
pp. 37-39
Author(s):  
V. N. Babichev ◽  
I. P. Savelyeva ◽  
M. I. Balabolkin
Keyword(s):  
Diabetes Mellitus ◽  
B Cells ◽  
Binding Sites ◽  
Binding Capacity ◽  
High Capacity ◽  
Experimental Diabetes Mellitus ◽  
Number Of Binding Sites ◽  
Pancreatic B Cells ◽  
Two Parameters

The receptor properties of pancreatic b-cells functionally attenuated under the effect of streptozotocin during therapy with sulfanilamides widely used in diabetes mellitus (glibenclamide, glipizide, and gliclazide) were studied. These drugs were shown to be characterized by the high capacity to specifically bind to receptors, which virtually do not differ from those of intact b-cells. The receptors were characterized by two parameters: the number of binding sites and dissociation constant. Glibenclamide has demonstrated high binding capacity. The binding of these agents was reversible. The authors do not identify the studied receptors of sulfanilamides with the K+-ATP channels which are also known as the active conductors of the information carried by sulfanilamides in the mechanism of insulin secretion.

scholarly journals Characterization of a thyroid-hormone-binding site on nuclear envelopes and nuclear matrices of the male-rat liver

1984 ◽  
Vol 219 (3) ◽  
pp. 1001-1007 ◽  
Author(s):  
Y A Lefebvre ◽  
J T Venkatraman
Keyword(s):  
Rat Liver ◽  
Binding Sites ◽  
Intact Animal ◽  
Binding Capacity ◽  
Specific Binding ◽  
Male Rat ◽  
Scatchard Analysis ◽  
Specific Binding Sites ◽  
Number Of Binding Sites

Nuclear envelopes and nuclear matrices were isolated from the male-rat liver. Incubation of 125I-labelled 3,3′,5-tri-iodothyronine (T3) with the nuclear-envelope fraction resulted in specific binding of T3 to the membranes. Maximum specific binding occurred at 30 degrees C after 2h incubation. Storage for 1 week at -80 degrees C resulted in no loss of binding. Scatchard analysis revealed a class of binding sites with KD 86 nM. 3,3′,5′-Tri-iodothyronine was as effective a competitor of [125I]T3 binding to nuclear envelopes as was L-T3 itself, and tri-iodothyroacetic acid was 70% as potent as T3. L- and D-thyronine did not compete for [125I]T3 binding. Incubation of nuclear envelopes with 0.6 M-NaCl before addition of T3 resulted in the complete loss of specific binding sites, whereas exposure of the membranes to 2.0 M-NaCl after incubation with T3 did not extract binding sites. Nuclear matrices, after incubation with [125I]T3 under the same conditions, were shown to possess a class of binding sites with a similar KD but with approx. 30% of the maximum binding capacity. Nuclear envelopes from hypothyroid animals may possess slightly lower numbers of binding sites compared with nuclear envelopes from the intact animal, whereas nuclear matrices from hypothyroid animals have the same number of binding sites as do nuclear envelopes from the intact animal. In conclusion, nuclear envelopes and nuclear matrices have a class of binding sites with relatively high affinity for T3. It is distinct from nuclear and cytosolic binding sites.

scholarly journals Characterization of pancreatic beta-cell receptors binding sulfanilamide drugs

1994 ◽  
Vol 40 (6) ◽  
pp. 47-50 ◽  
Author(s):  
V. N. Babichev ◽  
I. P. Savelyeva ◽  
M. I. Balabolkin
Keyword(s):  
Beta Cell ◽  
Binding Sites ◽  
Type Ii Diabetes ◽  
Specific Binding ◽  
Pancreatic Beta Cell ◽  
Type Ii ◽  
Cell Receptors ◽  
Number Of Binding Sites ◽  
Two Parameters

Analysis of pancreatic beta-cell receptors binding the sulfanilamide drugs widely used in therapy of type II diabetes, such as glybenclamide, glypizide, and glyclazide, showed that these drugs are characterized by excellent parameters of specific binding to these receptors. The receptors were tested for two parameters: number of binding sites and dissociation constant. Glybenclamide was the most active of the drugs we tested, the other two agents being less active. Binding of these agents was reversible. The problem of identification of the examined receptors of sulfanilamides with K+-ATP-sensitive channels, similarly active conductors of the information transported by the sulfanilamide drugs in the mechanism of insulin secretion, is discussed.

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.

Glucokinase in pancreatic B-cells and its inhibition by alloxan

1987 ◽  
Vol 115 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Sigurd Lenzen ◽  
Markus Tiedge ◽  
Uwe Panten
Keyword(s):  
Insulin Secretion ◽  
B Cells ◽  
B Cell ◽  
Metabolic Flux ◽  
Inhibitory Concentration ◽  
Pancreatic B Cell ◽  
High K ◽  
Pancreatic B Cells ◽  
Low K

Abstract. Characterization of glucokinase in pancreatic B-cells from ob/ob mice and from rat liver revealed identical characteristics. A narrow substrate specificity; high Km values for the two substrates, D-glucose and D-mannose, in the range of 10 and 20 mmol/l, respectively; higher Vmax values for D-glucose than for D-mannose; inhibition of glucokinase activities by D-mannoheptulose and by a specific glucokinase antibody. These characteristics distinguish glucokinase in soluble cytoplasmic fractions of pancreatic B-cells and liver from low Km hexokinases. Alloxan is a pancreatic B-cell cytotoxic agent, which has been widely used as a tool for the elucidation of the mechanisms of insulin secretion, because its inhibitory action on insulin secretion has been presumed to be intimately related to the mechanism of glucose-induced insulin secretion. Alloxan inhibited glucokinase but not hexokinase activity in cytoplasmic fractions of pancreatic B-cells and liver. The half maximal inhibitory concentration of alloxan was 5 μmol/l. Glucokinase activity was protected from alloxan toxicity only by D-glucose and D-mannose; the α anomer of D-glucose provided significantly greater protection than the β anomer. The non-metabolizable sugar 3-0-methyl-D-glucose did not provide protection of glucokinase activity against inhibition by alloxan. Thus, inhibition of pancreatic B-cell glucokinase may contribute to the inhibition of glucose-induced insulin secretion by alloxan. These results support the contention that glucokinase regulates the metabolic flux rate through the glycolytic chain in the pancreatic B-cell and thereby generates the signal for glucose-induced insulin secretion.

scholarly journals Characterization of the vitamin D-dependent Ca2+-binding sites in rat intestinal Golgi-enriched membrane fractions

1984 ◽  
Vol 218 (2) ◽  
pp. 347-354 ◽  
Author(s):  
J R F Walters ◽  
M M Weiser
Keyword(s):  
Vitamin D ◽  
Ionic Strength ◽  
Vitamin D Deficiency ◽  
Binding Sites ◽  
Control Diet ◽  
Specific Protein ◽  
High Affinity ◽  
Equilibrium Binding ◽  
Number Of Binding Sites

Rat intestinal Golgi-enriched membrane fractions take up Ca2+ by a vitamin D-dependent process that has been shown to recover within 15 min of repletion of vitamin D-deficient animals with intravenous 1,25-dihydroxycholecalciferol. The present paper reports studies characterizing the Ca2+-binding sites of these membrane fractions. Equilibrium binding of Ca2+ at concentrations between 5 and 400 microM showed significant decreases at all concentrations in membranes derived from vitamin D-deficient animals when compared with normal control-diet-fed animals. The predominant class of binding sites had a relatively high affinity for Ca2+ (KD approx. 3 microM). Vitamin D-deficiency did not change the affinity of this class of site, but decreased the number from 347 +/- 26 to 168 +/- 50 nmol of Ca2+ bound/mg of protein (means +/- S.D.). Mg2+ inhibited binding only at low Ca2+ concentrations, and the characteristics of this binding suggested positive co-operativity between two binding sites. Equimolar concentrations of Zn2+, La3+, Pb2+ and Mn2+ inhibited Ca2+ binding by over 50%. Increased ionic strength decreased Ca2+ binding by no more than half. Binding was maximal at pH 7.5 and half-maximal at pH 6.3. The large number of binding sites with relatively high affinity for Ca2+ suggests that it is unlikely that this binding is to any specific protein or to non-specific sites present on many proteins, and that the most likely sites are lipid molecules.

scholarly journals Efficient conjugation of anti-HBsAg antibody to modified core-shell magnetic nanoparticles (Fe3O4@SiO2/NH2)

Bioimpacts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 237-244
Author(s):  
Shahram Parvaneh ◽  
Fatemeh Khademi ◽  
Gisya Abdi ◽  
Abdolhamid Alizadeh ◽  
Ali Mostafaie
Keyword(s):  
Magnetic Nanoparticles ◽  
Sodium Periodate ◽  
Binding Capacity ◽  
High Capacity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Core Shell ◽  
Detection Techniques ◽  
B Virus ◽  
Further Development

Introduction: Further development of magnetic-based detection techniques could be of significant use in increasing the sensitivity of detection and quantification of hepatitis B virus (HBV) infection. The present work addresses the fabrication and characterization of a new bio-nano composite based on the immobilization of goat anti-HBsAg antibody on modified core-shell magnetic nanoparticles (NPs) by (3-aminopropyl) triethoxysilane (APTES), named Fe3O4@SiO2/NH2, and magnetic NPs modified by chitosan (Fe3O4@CS). Methods: At the first step, Fe3O4 was modified with the silica and APTES (Fe3O4@SiO2/NH2) and chitosan (Fe3O4@CS) separately. The goat anti-HBsAg antibody was activated by two different protocols: Sodium periodate and EDC-NHS. Then the resulted composites were conjugated with activated goat anti-HBsAg IgG. An external magnet collected Bio-super magnetic NPs (BSMNPs) and the remained solution was analyzed by the Bradford method to check the amount of attached antibody to the surface of BSMNPs. Results: The findings indicated that activation of antibodies by sodium periodate method 15-17 µg antibody immobilized on 1 mg of super magnetic nanoparticles (SMNPs). However, in the EDC-NHS method, 8-10 µg of antibody was conjugated with 1 mg of SMNPs. The resulting bio-magnetic NPs were applied for interaction with the HBsAg target using enzyme-linked immunosorbent assay (ELISA). About 1 µg antigen attached to 1 mg SMNPs, which demonstrated that the fabricated materials are applicable in the detection scope of HBsAg. Conclusion: In the present study, we developed new antibody-conjugated magnetic NPs for the detection of HBsAg using an efficient conjugation strategy. The results demonstrated that the binding capacity of Fe3O4@SiO2/NH2 was comparable with commercially available products. Our designed method for conjugating anti-HBsAg antibody to a magnetic nanoparticle opens the way to produce a high capacity of magnetic NPs.

scholarly journals Effects of ATP on the Interaction of Ca++, Mg++, and K+ with Fragmented Sarcoplasmic Reticulum Isolated from Rabbit Skeletal Muscle

1967 ◽  
Vol 50 (5) ◽  
pp. 1327-1352 ◽  
Author(s):  
Arselio P. Carvalho ◽  
Barbara Leo
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Binding Sites ◽  
Membrane Fraction ◽  
Binding Capacity ◽  
Cation Binding ◽  
The Other ◽  
Surface Binding ◽  
Ph Values ◽  
Number Of Binding Sites

Fragmented sarcoplasmic reticulum isolated from skeletal muscle of the rabbit has a cation-binding capacity of about 350 µeq/g of protein at neutral pH. The same binding sites bind Ca, Mg, K, and H ions and, consequently, the selective binding of Ca induced by ATP releases an amount of the other cations equivalent to the Ca taken up. At pH values below 6.2, an increasing number of binding sites are associated with H+, and ATP induces exchange of Ca mostly for H+. At pH values above 6.2, the binding sites exist in the form of Mg and K, and Ca is bound in exchange for these cations. The total bound Ca + Mg + K, expressed in microequivalents of cations bound per gram of protein, is approximately constant at various pCa values, which indicates a stoichiometric exchange of Ca for the other cations. To accomplish the same degree of exchange of Ca for other cations bound, in the absence of ATP, concentrations of free Ca++ of about 1000-fold higher than those needed in the presence of ATP are required in the medium. We cannot distinguish between a mechanism whereby Ca actively transported into a compartment of the microsomal vesicles containing also the binding sites is bound passively to these sites in exchange for Mg, K, and H and another in which ATP selectively increases the affinity of surface-binding sites for Ca. Irrespective of the mechanism of accumulation, the Ca retained does not contribute to the activity of the cation in the membrane fraction. Caffeine (10 mM) has no effect on the binding of Ca, but releases a more labile fraction of Ca, which presumably accumulates in excess of the bound Ca. Procaine (5 mM) antagonizes the effect of caffeine. Acetylcholine and epinephrine have no effect on the binding of Ca.

Synthesis, Characterization of the Mn(II) Complex of Rutin and Interactions between the Complex and Serum Albumins

2012 ◽  
Vol 549 ◽  
pp. 265-268 ◽  
Author(s):  
Hong Xia Li ◽  
Kun Jie Wang ◽  
De Yi Zhang ◽  
Yan Ping Wu ◽  
Hui Xia Feng ◽  
...  
Keyword(s):  
Serum Albumin ◽  
General Formula ◽  
Binding Sites ◽  
Binding Constants ◽  
Fluorescence Method ◽  
Serum Albumins ◽  
Thermogravimetric Analyses ◽  
Number Of Binding Sites

In this work, the complex of rutin-Mn has been synthesized. On the basis of elemental, thermogravimetric analyses, IR, the general formula of this complex, Na3Mn2•L(HCO3)3•3H2O is given. The interaction of serum albumin (BSA and HSA) with this complex has been studied by fluorescence method and the binding constants K (rutin-Mn-BSA: 3.1×108, 8.7×105; rutin-Mn-HSA: 3.3×107, 2.7×105) and the number of binding sites (rutin-Mn-BSA: 1.8, 1.2; rutin-Mn-HSA: 1.6, 1.1) has been obtained.

Abnormal Platelet Serotonin Uptake And Binding Sites In Myeloproliferative Disorders

1981 ◽  
Author(s):  
C Caranobe ◽  
P Sié ◽  
C Nouvel ◽  
G Laurent ◽  
J Pris ◽  
...  
Keyword(s):  
Binding Sites ◽  
High Capacity ◽  
Myeloproliferative Disorders ◽  
Binding Assays ◽  
Dense Granules ◽  
Plot Analysis ◽  
Binding Data ◽  
Plasmatic Membrane ◽  
Number Of Binding Sites ◽  
5 Ht Uptake

We previously shown that the platelets of patients suffering from myeloproliferative disorders (MD) present not only a reduced capacity to store serotonin (5 HT) in their dense granules but also a dramatic reduction in the initial velocity (Vi) of 5 HT uptake ; this suggests that the abnormalities are not restricted to the dense granules but involve the transport mechanism accross the platelet membrane.The present study concerns the 5 HT binding sites of MD platelets which present such a reduction of the Vi Max (Li- neweaver-Burke plot) of the 5 HT uptake. Binding assays were performed according to the method of Schik et al. (Biochem. Pharmacol. 1979, 28, 2667). Schatchard plot analysis of the binding data revealed two binding sites both in normals and patients : site A with a high affinity and a low capacity and site B with a low affinity and a high capacity.Thus the abnormal 5 HT transport accross the plasmatic membrane is the consequence of a quantitative reduction of the 5 HT binding sites and not of a qualitative defect of these sites. Nevertheless, in spite of the reduction of the number of binding sites, 5 HT-induced platelet aggregation was found normal in these patients.

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