scholarly journals The Ins(1,4,5)P3 binding site of bovine adrenocortical microsomes: function and regulation

1989 ◽  
Vol 260 (2) ◽  
pp. 593-596 ◽  
Author(s):  
S Palmer ◽  
M J O Wakelam
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Specific Binding ◽  
Cell Signalling ◽  
Single Population ◽  
Lower Affinity ◽  
Specific Binding Sites ◽  
Kinase C ◽  
And Function ◽  
Gamma S

Adrenocortical microsomes possess a single population of Ins(1,4,5)P3-specific binding sites [IC50 5.9 +/- 0.9 nM; Palmer, Hughes, Lee & Wakelam (1988) Cell. Signalling 1, 147-156]. Competition studies showed that Ins(1:2-cyclic,4,5)P3 exhibits a 21-fold lower affinity for the site than Ins(1,4,5)P3 (IC50 124 +/- 16 nM). The affinity of the binding sites for Ins(1,4,5)P3 was not influenced by the non-hydrolysable GTP analogues GTP gamma S and Gpp[NH]p or by preincubation of the binding protein with a preparation of partially purified protein kinase C in the presence of ATP and TPA (12-O-tetradecanoylphorbol 13-acetate). These observations are discussed with reference to the identify and function of the Ins(1,4,5)P3 binding site.

scholarly journals Structure of a highly acidic β-lactamase from the moderate halophileChromohalobactersp. 560 and the discovery of a Cs+-selective binding site

2015 ◽  
Vol 71 (3) ◽  
pp. 541-554 ◽  
Author(s):  
Shigeki Arai ◽  
Yasushi Yonezawa ◽  
Nobuo Okazaki ◽  
Fumiko Matsumoto ◽  
Chie Shibazaki ◽  
...  
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Nuclear Power ◽  
Specific Binding ◽  
Radioactive Isotopes ◽  
Titration Calorimetry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Specific Binding Sites ◽  
Enzymatic Function

Environmentally friendly absorbents are needed for Sr2+and Cs+, as the removal of the radioactive Sr2+and Cs+that has leaked from the Fukushima Nuclear Power Plant is one of the most important problems in Japan. Halophilic proteins are known to have many acidic residues on their surface that can provide specific binding sites for metal ions such as Cs+or Sr2+. The crystal structure of a halophilic β-lactamase fromChromohalobactersp. 560 (HaBLA) was determined to resolutions of between 1.8 and 2.9 Å in space groupP31using X-ray crystallography. Moreover, the locations of bound Sr2+and Cs+ions were identified by anomalous X-ray diffraction. The location of one Cs+-specific binding site was identified in HaBLA even in the presence of a ninefold molar excess of Na+(90 mMNa+/10 mMCs+). From an activity assay using isothermal titration calorimetry, the bound Sr2+and Cs+ions do not significantly affect the enzymatic function of HaBLA. The observation of a selective and high-affinity Cs+-binding site provides important information that is useful for the design of artificial Cs+-binding sites that may be useful in the bioremediation of radioactive isotopes.

Spectral investigations of the interaction of some porphyrins with bovine serum albumin

2000 ◽  
Vol 04 (02) ◽  
pp. 147-157 ◽  
Author(s):  
SHAMPA CHATTERJEE ◽  
T. S. SRIVASTAVA
Keyword(s):  
Energy Transfer ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Binding Site ◽  
Binding Sites ◽  
Bovine Serum ◽  
Tertiary Structure ◽  
Specific Binding ◽  
Specific Binding Sites ◽  
Cd Studies

The binding of meso-tetrakis[4-(carboxymethyleneoxy)phenyl]porphyrin (T4CPP), meso-tetrakis[3-(carboxymethyleneoxy)phenyl]porphyrin (T3CPP) and meso-tetrakis[3,4-bis(carboxymethyl-eneoxy)phenyl]porphyrin (T3, 4BCPP) with bovine serum albumin (BSA) at pH 7.4 has been studied at 420 nm in detail. The results show hypochromicity along with a red shift in the Soret band of the porphyrins. This suggests that these porphyrins bind to BSA as monomers. Further analysis of these data supports the non-interactive binding of T4CPP and T3CPP with BSA and the cooperative binding of T3, 4BCPP with BSA. These binding data have been interpreted in terms of one specific binding site and several non-specific binding sites on BSA for the porphyrins. The absorption spectral changes of the porphyrins between 400 and 450 nm when titrated with BSA suggest that there is another specific binding site on BSA for the porphyrins. These two specific binding sites have also been supported by circular dichroism (CD) studies. The absorption spectral and CD studies on the interactions of the porphyrins with BSA further suggest that these interactions are dependent on the number and configuration of substituents in the phenyl groups of the porphyrins. The contact energy transfer from the aromatic amino acid residues tryptophan and tyrosine of BSA to the porphyrins in the BSA–porphyrin complexes has also been studied using fluorescence spectroscopy. These energy transfer data show the energy transfer from tryptophan to the porphyrins for their binding to site I of BSA and from tyrosine to the porphyrins for their binding to site II of BSA. Unfolding studies of the BSA–porphyrin systems indicate that the tertiary structure is essential for the binding of the porphyrins. A correlation between the accumulation of99 mTc -labelled T4CPP and T3, 4BCPP in tumour tissue and their binding at site II of BSA is possible. The interaction of the porphyrins can also be used as a model for mitochondrial interactions.

Aldosterone binding in isolated tubules I. Biochemical determination in proximal and distal parts of the rabbit nephron

1982 ◽  
Vol 242 (1) ◽  
pp. F63-F68 ◽  
Author(s):  
N. Farman ◽  
A. Vandewalle ◽  
J. P. Bonvalet
Keyword(s):  
Binding Sites ◽  
Specific Binding ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Nuclear Fraction ◽  
Lower Affinity ◽  
High Affinity ◽  
Specific Binding Sites ◽  
Collecting Tubules ◽  
Binding Curve

Microbiochemical methods were applied to proximal tubules (PCT) and a mixture of distal and cortical collecting tubules (D + C) of rabbit kidney in order to define aldosterone binding sites. For each experiment, after incubation of kidney pyramids with [3H]aldosterone ([3H]A), either alone or in the presence of an excess unlabeled A, 100-150 mm of both categories of tubules were microdissected using collagenase. Specific binding was determined on the nuclear fraction of each sample. Aldosterone concentrations ranged from 2 X 10(-9) to 4.5 X 10(-8) M. No specific binding was detectable in PCT. Specific binding in D + C increased rapidly as a function of [3H]A concentration up to 5 X 10(-9) M and then more slowly. No plateau was reached. Both the absence of saturation of the binding curve and the curvilinear aspect of the Scatchard plot suggested the presence of two binding sites, one of high affinity, presumably a mineralocorticoid site, and the other of lower affinity, possibly a glucocorticoid site. These experiments suggest that the distal structures of the nephron, located in the cortex, are the main sites of binding of aldosterone and contain a high number of specific binding sites for this hormone.

scholarly journals Columnar aggregates of crown ether substituted phthalocyanines perpendicularly anchored on a surface via a selective binding site

2002 ◽  
Vol 06 (09) ◽  
pp. 563-570 ◽  
Author(s):  
Thierry Thami ◽  
Christophe Chassenieux ◽  
Christian Fretigny ◽  
Jean-Paul Roger ◽  
Felix Steybe
Keyword(s):  
Crown Ether ◽  
Binding Site ◽  
Binding Sites ◽  
Silica Surface ◽  
Specific Binding ◽  
Selective Binding ◽  
Force Microscopy ◽  
Specific Binding Sites ◽  
Atomic Force ◽  
Uv Visible

The purpose of this work is to anchor perpendicularly to a surface the aggregates obtained by complexation of crown-ether substituted lutetium bisphthalocyanine, [(15 C 5)4 Pc ]2 Lu , in the presence of KSCN . In order to orientate these aggregates perpendicularly to the substrate, silica surface is grafted with an unsymmetrical lutetium bisphthalocyanine substituted, on one macrocycle by four crown ether subunits, and on the other one with four lateral chains terminated by a carboxylic group. The latter compound is used as a selective binding site to anchor pillar-like aggregates formed in solution. The aggregates were characterized in a mixture of chloroformic based solution by UV-visible and light scattering experiments and gave evidence for the formation of rod-like particles in the presence of excess of KSCN . Then, the aggregates were deposited on surfaces and their morphologies were studied by atomic force microscopy (AFM). In the case of substrates having non-specific binding sites such as silica and functionalized silica with 3-trimethoxy-propylaminosilane, rods were observed lying parallel on the surface. In the case of the substrate grafted with the selective binding site, single columns of these supramolecular assemblies perpendicular to the surface have been observed by AFM.

scholarly journals Specific Binding of Rubidium in Chlorella

1962 ◽  
Vol 45 (5) ◽  
pp. 959-977 ◽  
Author(s):  
Dan Cohen
Keyword(s):  
Active Transport ◽  
Binding Sites ◽  
Specific Binding ◽  
High Concentration ◽  
External Concentration ◽  
Specific Binding Sites ◽  
Dense Suspension ◽  
Concentration Of Ions ◽  
The Individual ◽  
A Site

Specific binding sites for potassium, which may be components of the carriers for active transport for K in Chlorella, were characterized by their capacity to bind rubidium. A dense suspension was allowed to take up Rb86 from a low concentration of Rb86 and a high concentration of ions which saturate non-specific sites. The amount bound was derived from the increase in the external concentration of Rb86 following addition of excess potassium. The sites were heterogeneous. The average affinity of Rb and various other ions for the sites was determined by plotting the degree of displacement of Rb86 against log molar concentration of the individual ions. Interpolation gave the concentration for 50 per cent displacement of Rb, which is inversely related to affinity. The order of affinity was not changed when the cells were frozen, or boiled either in water or in 70 per cent ethanol. The affinity is maximal for ions with a crystalline radius of 1.3 to 1.5 A and a high polarizability, and is not related to the hydrated radius or valency. It is suggested that binding groups in a site are rigidly arranged, the irregular space between them being 2.6 to 3.0 A across, so that affinity is high for ions of this diameter and high polarizability.

Studies of the uptake of macromolecules by cells. I. Uptake of proteins by cells of the Ehrlich–Lettré ascites carcinoma

1968 ◽  
Vol 46 (12) ◽  
pp. 1443-1450 ◽  
Author(s):  
Y. C. Choi ◽  
E. R. M. Kay
Keyword(s):  
Nucleic Acid ◽  
Cell Membrane ◽  
Binding Sites ◽  
Specific Binding ◽  
Protein Uptake ◽  
Specific Binding Sites ◽  
Model Protein ◽  
Uptake Process ◽  
Kinetics Of ◽  
Protein Treatment

The uptake of protein by cells of the Ehrlich–Lettré ascites carcinoma was characterized kinetically by using hemoglobin as a model protein. An attempt was made to show that the process is not an artefact due to nonspecific adsorption of protein to the cell membrane. The kinetics of the uptake process suggested that an interaction exists between the exogenous protein and specific binding sites on the membrane. Acetylation of hemoglobin enhanced the rate of uptake of this protein. Treatment of cells with neuraminidase, phospholipase A, and Pronase resulted in an inhibition of protein uptake. The experimental evidence for the uptake of hemoglobin was supported by evidence that L-serine-U-14C-labelled hemoglobin is transported into the cytoplasm and utilized subsequently, resulting in labelling of the nucleic acid nucleotides.

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