STUDIES ON ACTH-BINDING ANTIBODIES: CHARACTERIZATION OF IMMUNOLOGICAL SPECIFICITIES

1969 ◽  
Vol 62 (3) ◽  
pp. 521-536 ◽  
Author(s):  
M. L. Aubert ◽  
J.-P. Felber
Keyword(s):  
Binding Sites ◽  
Competitive Inhibition ◽  
Biologically Active ◽  
Active Part ◽  
Terminal Portion ◽  
Plasma Acth ◽  
Acth Fragments ◽  
Selection Of

ABSTRACT In investigations on the production and the specificity of anti-ACTH antibodies used for radioimmunoassay, differences have been observed between the various antibodies obtained. It was shown by means of competitive inhibition with different ACTH fragments that the binding of the ACTH molecule to its antibody can occur at different sites along the ACTH peptide. By varying the concentrations of the fragments and the conditions of the assays, it was possible to study the properties of each antibody. Thus antibodies which bind the N-terminal portion, or which exclusively bind the biologically active part of the ACTH chain (1–20), are the most suitable for radioimmunoassay. It was found, however, that the production of antiserum was generally more frequent when binding occurred to the C-terminal portion of the ACTH peptide. Should the presence of such fragments in plasma be confirmed, then the use of these antisera could lead to erroneous measurement of biologically inactive ACTH fragments. Thus, this study reveals that a selection of the antibody for specificity might be necessary for its application to the radioimmunoassay of plasma ACTH, and that this selection could be performed with the use of ACTH fragments. An approach to the problem of binding sites between antigen and antibody has been described and the possibility of introducing a radioimmunoassay for plasma ACTH fragments discussed.

Isolation And Characterization Of The Vitamin K Dependent Domain Of Human Prothrombin

1981 ◽  
Author(s):  
C Dodé ◽  
A Thiesce ◽  
D Labie ◽  
J Elion
Keyword(s):  
Conformational Change ◽  
Vitamin K ◽  
Disulfide Bond ◽  
Binding Sites ◽  
Terminal Portion ◽  
Isolation And Characterization ◽  
Cooperative Process ◽  
Dependent Domain ◽  
Stimulation Of

Chymotryptic cleavage of human prothrombin (hPt) produces two fragments of 68000 and 5000 MW respectively. These two species were separated by Ba citrate adsorption and Sephadex G100 chromatography. The 68000 MW species corresponds to hPt (des 1-44) and has lost all the vitamin K dependent properties of hPt : adsorption on Ba citrate, Ca+2 and phospholipid dependent stimulation of the activation by FXa, presence of strong Ca+2 binding sites (as shown by dialysis equilibrium) and Ca+2 induced fluorescence quenshing. The 5000 MW species corresponds to the N-terminal portion of hPt (residues 1-41). It contains the 10 Gla residues and the 17-22 disulfide bond. This peptide is quantitatively adsorbed on Ba citrate. Activation of hPt in a mixture containing FXa, Ca+2 and phospholipid is drastically inhibited by the addition of peptide 1-41 (≃ 50 % inhibition for a 1/1 peptide/Pt ratio, ≃ 7 % for a 40/1 ratio).Ca+2 produces a quenshing of the intrinsic fluorescence of peptide 1-41 (λ emission = 355 nm). This quenshing plateausat 40 % of the initial fluorescence at 3 mM Ca+2. The plot of the fluorescence quenshing versus Ca+2 concentration however is not cooperative. Mn+2 and Mg+2 also induced fluorescence quenshing but to a lesser extent. Hence peptide 1-44 represents a functionnal domain in itself interacting with Ca+2 and phospholipid. It contains only one Trp (residue 41), showing directly the involvment of this residue in the Ca+2 induced fluorescence quenshing observed for Pt fragment (FI) and Pt. This isolated vitamin K dependent domain therefore retains many of the vitamin K dependent properties of FI or Pt, but shows differences in the Ca+2 induced conformational change in that it is no longer a cooperative process.

scholarly journals Characterization of a binding protein for leukemia inhibitory factor localized in extracellular matrix

1993 ◽  
Vol 122 (3) ◽  
pp. 713-719 ◽  
Author(s):  
A Mereau ◽  
L Grey ◽  
C Piquet-Pellorce ◽  
JK Heath
Keyword(s):  
Extracellular Matrix ◽  
Binding Sites ◽  
Leukemia Inhibitory Factor ◽  
Protein A ◽  
Biologically Active ◽  
Inhibitory Factor ◽  
Stable Complex ◽  
Culture Dish ◽  
Chemical Cross Linking

Leukemia Inhibitory Factor (LIF) interacts with two classes of high affinity binding sites on rat UMR cells cultured in monolayer. One class of binding sites was found to be localized in the extracellular matrix (ECM) after removal of cells from the culture dish. The interaction of LIF with ECM-localized binding sites is not dependent upon either glycosylation of LIF or the presence of extracellular glycosyaminoglycans. Chemical cross-linking studies demonstrate that LIF interacts with a 200-kD cell-associated protein and a 140-kD ECM-localized protein. A 140-kD protein could also be specifically precipitated from solubilised metabolically radiolabeled UMR ECM by antibodies directed against LIF by virtue of its ability to form a stable complex with unlabeled LIF. In addition, soluble LIF associated with this ECM-localized protein is biologically active in terms of inhibition of ES cell differentiation. The properties of ECM-localized 140-kD species are very similar to those of the secreted form of the LIF receptor suggesting that the ECM localization of LIF and LIF signal transduction may be closely coupled.

Cloning and characterization of a human leptin receptor using a biologically active leptin immunoadhesin

1997 ◽  
Vol 18 (1) ◽  
pp. 77-85 ◽  
Author(s):  
S-M Luoh ◽  
F Di Marco ◽  
N Levin ◽  
M Armanini ◽  
M-H Xie ◽  
...  
Keyword(s):  
Body Weight ◽  
Binding Sites ◽  
Leptin Receptor ◽  
Short Form ◽  
Biologically Active ◽  
Expression Cloning ◽  
Kidney Cells ◽  
Long Form

ABSTRACT Leptin, the product of the ob gene, is a hormone secreted by fat cells which is primarily involved in the regulation of body weight. We have generated a leptin immunoadhesin (leptin-IgG) which was more potent than leptin alone at reducing body weight and food intake when injected into ob/ob mice. This molecule was used to identify high affinity binding sites on human embryonic 293 kidney cells and subsequently to isolate a cDNA encoding the leptin receptor from this cell line by expression cloning. This receptor corresponds to the short form of the recently isolated leptin receptor. Analysis of the expression pattern of the two forms of receptor by Northern blot, in situ hybridization and quantitative PCR showed that the receptor is expressed in most tissues but that the long form is prevalent in the hypothalamus.

On the characterization of novel biologically active steroids: Selection of lipophilicity models of newly synthesized steroidal derivatives by classical and non-parametric ranking approaches

2019 ◽  
Vol 80 ◽  
pp. 23-30 ◽  
Author(s):  
Milica Ž. Karadžić Banjac ◽  
Strahinja Z. Kovačević ◽  
Lidija R. Jevrić ◽  
Sanja O. Podunavac-Kuzmanović ◽  
Anamarija I. Mandić
Keyword(s):  
Biologically Active ◽  
Steroidal Derivatives ◽  
Selection Of ◽  
Non Parametric

Origins of the First Cell. A New Model for the Spontaneous Formation of the First Living Cell Based on a Novel Approach

1977 ◽  
Vol 32 (11-12) ◽  
pp. 1003-1010 ◽  
Author(s):  
Semih Erhan
Keyword(s):  
Binding Sites ◽  
Biologically Active ◽  
Active Protein ◽  
Evolutionary Selection ◽  
Novel Approach ◽  
Long Time ◽  
Necessary And Sufficient ◽  
Critical Regions ◽  
Emergence Of Life ◽  
Selection Of

Abstract Whether proteins or nucleic acids were responsible for the emergence of life has been debated for a long time. Taking the observation that families of proteins display a remarkable invariance of their amino acid sequence around critical regions, such as active/binding sites, even though these proteins may represent considerable evolutionary diversity, as the naturally provided evidence of evolutionary selection of a working system, the idea is developed that: 1. Proteins had to have been first informational macromolecules that were necessary and sufficient to lead to the emergence of life; 2. it is impossible for a nucleic acid molecules to have formed, by chance, whose base sequence could yield a biologically active protein. A model is proposed to account for the emergence of the first sucessful cell according to this approach.

ISOLATION, PURIFICATION, AND CHARACTERIZATION OF γ-LIPOTROPIC HORMONE FROM SHEEP PITUITARY GLANDS

1967 ◽  
Vol 45 (7) ◽  
pp. 1163-1174 ◽  
Author(s):  
M. Chrétien ◽  
Choh Hao Li
Keyword(s):  
Biologically Active ◽  
Terminal Portion ◽  
Purification And Characterization ◽  
Considerable Evidence ◽  
Isolation And Characterization ◽  
Structure Activity ◽  
C Terminus ◽  
Pituitary Glands ◽  
Peptide Biosynthesis

The isolation and characterization of a new biologically active polypeptide from sheep pituitary glands is described. Considerable evidence suggests that the structure of the new molecule, designated γ-lipotropin, is identical with the N-terminal portion (sequence 1–58) of β-lipotropin and, therefore, that γ-lipotropin contains at its C-terminus the amino acid sequence of β-melanophore-stirnulating hormone (β-MSH). The implications of these results are discussed in relation to the mechanism of pituitary peptide biosynthesis and to the structure–activity relationships between sheep β-MSH and lipotropic hormones.

Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability

1968 ◽  
Vol 26 ◽  
pp. 442-443 ◽  
Author(s):  
L.E. Murr ◽  
A.B. Draper
Keyword(s):  
Electron Microscopy ◽  
State Physics ◽  
Test Material ◽  
Milling Machine ◽  
Rotary Table ◽  
Solid State Physics ◽  
Materials Properties ◽  
Transmission Electron ◽  
Selection Of

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

Characterization of Thromboxane A2/Prostaglandin H2 Receptors in Porcine Coronary Artery -The Inhibitory Effect of a Novel Dibenzoxepin Derivative, KW-3635

1992 ◽  
Vol 67 (05) ◽  
pp. 582-584 ◽  
Author(s):  
Ichiro Miki ◽  
Akio Ishii
Keyword(s):  
Coronary Artery ◽  
Binding Sites ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Scatchard Analysis ◽  
Single Class ◽  
Porcine Coronary Artery ◽  
Equilibrium Binding ◽  
H2 Receptors

SummaryWe characterized the thromboxane A2/prostaglandin H2 receptors in porcine coronary artery. The binding of [3H]SQ 29,548, a thromboxane A2 antagonist, to coronary arterial membranes was saturable and displaceable. Scatchard analysis of equilibrium binding showed a single class of high affinity binding sites with a dissociation constant of 18.5 ±1.0 nM and the maximum binding of 80.7 ± 5.2 fmol/mg protein. [3H]SQ 29,548 binding was concentration-dependently inhibited by thromboxane A2 antagonists such as SQ 29,548, BM13505 and BM13177 or the thromboxane A2 agonists such as U46619 and U44069. KW-3635, a novel dibenzoxepin derivative, concentration-dependently inhibited the [3H]SQ 29,548 binding to thromboxane A2/prosta-glandin H2 receptors in coronary artery with an inhibition constant of 6.0 ± 0.69 nM (mean ± S.E.M.).

Predicting the Strength of Stacking Interactions Between Heterocycles and Aromatic Amino Acid Side Chains

2019 ◽  
Author(s):  
Andrea N. Bootsma ◽  
Analise C. Doney ◽  
Steven Wheeler
Keyword(s):  
Amino Acid ◽  
Binding Sites ◽  
Aromatic Amino Acid ◽  
Aromatic Amino Acids ◽  
Biologically Active ◽  
Side Chains ◽  
Stacking Interactions ◽  
Inhibitor Binding ◽  
Protein Binding Sites ◽  
Amino Acid Side Chains

<p>Despite the ubiquity of stacking interactions between heterocycles and aromatic amino acids in biological systems, our ability to predict their strength, even qualitatively, is limited. Based on rigorous <i>ab initio</i> data, we have devised a simple predictive model of the strength of stacking interactions between heterocycles commonly found in biologically active molecules and the amino acid side chains Phe, Tyr, and Trp. This model provides rapid predictions of the stacking ability of a given heterocycle based on readily-computed heterocycle descriptors. We show that the values of these descriptors, and therefore the strength of stacking interactions with aromatic amino acid side chains, follow simple predictable trends and can be modulated by changing the number and distribution of heteroatoms within the heterocycle. This provides a simple conceptual model for understanding stacking interactions in protein binding sites and optimizing inhibitor binding in drug design.</p>

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