Evaluation of labelled monoclonal antibodies by simultaneous estimation of the association constant, the immunoreactive fraction, and the number of effective binding sites on the specific target

1992 ◽  
Vol 151 (1-2) ◽  
pp. 97-106 ◽  
Author(s):  
Jan G. Fjeld ◽  
Arne Skretting
Keyword(s):  
Monoclonal Antibodies ◽  
Binding Sites ◽  
Association Constant ◽  
Simultaneous Estimation ◽  
Specific Target

THE MOLECULAR ORGANIZATION OF HUMAN ALPHA 2-MACROGLOBULIN. AN IMMUNO ELECTRON MICROSCOPIC STUDY WITH MONOCLONAL ANTIBODIES

1987 ◽  
Author(s):  
E Delain ◽  
M Barrav ◽  
J Tapon-Bretaudière ◽  
F Pochon ◽  
F Van Leuven
Keyword(s):  
Monoclonal Antibodies ◽  
Binding Sites ◽  
Divalent Cations ◽  
The Other ◽  
Molecular Organization ◽  
Cellular Receptor ◽  
Electron Microscopic ◽  
Microscopic Method ◽  
Bait Region ◽  
Electron Microscopic Method

Electron microscopy is a very convenient method to localize the epitopes of monoclonal antibodies (mAbs) at the surface of macromolecules for studying their tree-dimensional organization.We applied this immuno-electron microscopic method to human ct2-macroglobulin (ct2M). 29 anti-α2M mAbs have been tested with the four different forms of a2M : native and chymotrypsin-transformed tetramers, and the corresponding dimers, obtained by dissociation with divalent cations. These mAbs can be classified in three types : those which are specific for 1) the H-like transformed molecules, 2) the native molecules, and 3) those which can react with both forms of α2M.1) Among the H-like α2M specific mAbs, several react with the 20 kD-domain which is recognized by the cellular receptor of transformed a2M. This domain is located at the carboxyterminal end of each monomer. One IgG binds to the end of two adjacent tips of the H-like form.The other mAbs of this type bind to the α2M tips at non-terminal positions. Intermolecular connections built polymers of alternating α2M and IgG molecules.2) Among the native a2M-specific mAbs some are able to inhibit the protease-induced transformation of the native α2M. The binding sites of these mAbs are demonstrated on the native half-molecules. One of these mAbs was also able to react with transformed dimers, in a region corresponding very likely to an inaccessible epitope in the tetrameric transformed α2M molecule.3) Among the mAbs of this type, only two were able to inhibit the protease-induced transformation of α2M. Obviously, their epitopes should be close to the bait region of α2M. The other mAbs reacting with both α2M forms did not inhibit the α2M transformation.All these mAbs can be distinguished by the structure of the immune complexes formed with all forms of α2M. The epitopes are more easily located on the dimers and on the H-like transformed α2M than on the native molecules.From these observations, we propose a new model of the tree-dimensional organization of the human α2M in its native and transformed configurations, and of its protease-induced transformation.

scholarly journals Inhibition of acanthamoeba actomyosin-II ATPase activity and mechanochemical function by specific monoclonal antibodies.

1984 ◽  
Vol 99 (3) ◽  
pp. 1024-1033 ◽  
Author(s):  
D P Kiehart ◽  
T D Pollard
Keyword(s):  
Monoclonal Antibodies ◽  
Atpase Activity ◽  
Conformational Changes ◽  
Binding Sites ◽  
Polyclonal Antibodies ◽  
Myosin Ii ◽  
Antigenic Site ◽  
Actin Binding ◽  
Filamentous Form ◽  
Antibody Effects

Monoclonal and polyclonal antibodies that bind to myosin-II were tested for their ability to inhibit myosin ATPase activity, actomyosin ATPase activity, and contraction of cytoplasmic extracts. Numerous antibodies specifically inhibit the actin activated Mg++-ATPase activity of myosin-II in a dose-dependent fashion, but none blocked the ATPase activity of myosin alone. Control antibodies that do not bind to myosin-II and several specific antibodies that do bind have no effect on the actomyosin-II ATPase activity. In most cases, the saturation of a single antigenic site on the myosin-II heavy chain is sufficient for maximal inhibition of function. Numerous monoclonal antibodies also block the contraction of gelled extracts of Acanthamoeba cytoplasm. No polyclonal antibodies tested inhibited ATPase activity or gel contraction. As expected, most antibodies that block actin-activated ATPase activity also block gel contraction. Exceptions were three antibodies M2.2, -15, and -17, that appear to uncouple the ATPase activity from gel contraction: they block gel contraction without influencing ATPase activity. The mechanisms of inhibition of myosin function depends on the location of the antibody-binding sites. Those inhibitory antibodies that bind to the myosin-II heads presumably block actin binding or essential conformational changes in the myosin heads. A subset of the antibodies that bind to the proximal end of the myosin-II tail inhibit actomyosin-II ATPase activity and gel contraction. Although this part of the molecule is presumably some distance from the ATP and actin-binding sites, these antibody effects suggest that structural domains in this region are directly involved with or coupled to catalysis and energy transduction. A subset of the antibodies that bind to the tip of the myosin-II tail appear to inhibit ATPase activity and contraction through their inhibition of filament formation. They provide strong evidence for a substantial enhancement of the ATPase activity of myosin molecules in filamentous form and suggest that the myosin filaments may be required for cell motility.

Euonymus europaeus lectin as an endothelial and epithelial marker in canine tissues

1992 ◽  
Vol 26 (2) ◽  
pp. 114-121 ◽  
Author(s):  
F. Roussell ◽  
J. Dalion ◽  
J. C. Wissocq
Keyword(s):  
Endothelial Cells ◽  
Monoclonal Antibodies ◽  
Binding Site ◽  
Binding Sites ◽  
Human Tissues ◽  
Probable Structure ◽  
Euonymus Europaeus ◽  
Epithelial Marker ◽  
Endothelial Marker

The Euonymus europaeus agglutinin (EEA) is an endothelial marker in mammalia. In canine tissues, 4 types of endothelial cells (general, nervous, arterial, hepatic) were identified by the presence of the EEA receptor and by its sensitivity to neuraminidase enhancement. In adult dogs, EEA binding saccharides had endothelial or epithelial distributions and reactivities similar to those described for human tissues. Different EEA reactivities were observed between fetal, neonatal and adult canine tissues mainly at the arterial level. These findings suggest that the development of the binding sites is not identical in dog and man. Related lectins and monoclonal antibodies were used to characterize the EEA binding site, and the probable structure of the EEA binding saccharide in endothelial cells appeared to be αGal (1,3) βGal (1,4) GIcNAc.

Cell adhesion and phagocytosis promoted by monoclonal antibodies not directed against fibronectin receptors

1988 ◽  
Vol 90 (2) ◽  
pp. 201-214 ◽  
Author(s):  
F. Grinnell ◽  
C.H. Ho ◽  
T.L. Tuan
Keyword(s):  
Monoclonal Antibodies ◽  
Cell Adhesion ◽  
Binding Sites ◽  
Cell Spreading ◽  
The Other ◽  
Immunofluorescence Staining ◽  
Baby Hamster Kidney ◽  
Bhk Cells ◽  
Reducing Conditions ◽  
Latex Beads

In this report we describe cell adhesion and phagocytosis promoted by two monoclonal antibodies that were selected for immunofluorescence staining of non-permeabilized baby hamster kidney (BHK) cells. Anti-BHK1 staining was heaviest along cell margins, whereas anti-BHK2 staining was continuous along cell margins. Neither antibody stained elongated plaque structures such as were observed when cells were reacted with antibodies to fibronectin (FN) receptors. The monoclonal antibodies functioned as adhesion ligands in four different assays: attachment to culture dishes, spreading, binding of latex beads and phagocytosis. Anti-BHK1 and anti-BHK2 promoted attachment to culture dishes similarly, but anti-BHK2 was more effective at promoting cell spreading. Antibody-promoted cell spreading was inhibited by the peptides Ser-Asp-Gly-Arg and Gly-Arg-Gly-Asp-Ser-Pro but not by other, related, peptides tested. The monoclonal antibodies also promoted binding of latex beads, and the bead binding sites were motile, on the basis of their ‘capping’ response. Nevertheless, anti-BHK2 beads were phagocytosed by cells 5- to 20-fold more efficiently than anti-BHK1 beads. The binding sites for anti-BHK1 and anti-BHK2 were characterized by immunoprecipitation experiments. Anti-BHK1 binding sites contained 50K (K = 10(3) Mr) and 88K components under non-reducing conditions that migrated as a 51/53K doublet and a 93K component under reducing conditions. On the other hand, anti-BHK2 binding sites contained 88K and 110K components under non-reducing conditions that shifted to apparent 107K and 128K values when measured under reducing conditions.

scholarly journals Probing the Flavivirus Membrane Fusion Mechanism by Using Monoclonal Antibodies

2007 ◽  
Vol 81 (20) ◽  
pp. 11526-11531 ◽  
Author(s):  
Karin Stiasny ◽  
Samantha Brandler ◽  
Christian Kössl ◽  
Franz X. Heinz
Keyword(s):  
Monoclonal Antibodies ◽  
Fusion Protein ◽  
Binding Sites ◽  
Fusion Inhibition ◽  
Tick Borne Encephalitis ◽  
Target Membrane ◽  
Initial Interaction ◽  
Tick Borne Encephalitis Virus ◽  
Late Stages

ABSTRACT In this study, we investigated in a flavivirus model (tick-borne encephalitis virus) the mechanisms of fusion inhibition by monoclonal antibodies directed to the different domains of the fusion protein (E) and to different sites within each of the domains by using in vitro fusion assays. Our data indicate that, depending on the location of their binding sites, the monoclonal antibodies impaired early or late stages of the fusion process, by blocking the initial interaction with the target membrane or by interfering with the proper formation of the postfusion structure of E, respectively. These data provide new insights into the mechanisms of flavivirus fusion inhibition by antibodies and their possible contribution to virus neutralization.

scholarly journals Competitive Binding of Novel Cyanine Dye AK3-5 and Europium Coordination Complexes to DNA

2019 ◽  
Keyword(s):  
Dna Binding ◽  
Fluorescence Intensity ◽  
Binding Sites ◽  
Association Constant ◽  
Antitumor Agents ◽  
Coordination Complexes ◽  
Cyanine Dye ◽  
Europium Complexes ◽  
Intensity Decrease ◽  
Dna Binding Sites

The present study was undertaken to assess the applicability of the novel trimethine cyanine dye AK3-5 as a competitive ligand for the antitumor agents, Eu(III) coordination complexes (EC), in the DNA-containing systems, using the displacement assay as an analytical instrument. The analysis of fluorescence spectra revealed a strong association of AK3-5 with nucleic acids, with the strength of interaction being higher for the double stranded DNA, compared to the single-stranded RNA. The binding parameters of the cyanine dye have been determined in terms of the McGhee & von Hippel neighbouring site-exclusion model and a classical Langmuir model. The AK3-5 association constant in the presence of DNA was found to be equal to 5.1×104 M-1, which is consistent to those of the well-known DNA intercalators. In turn, the binding of the cyanine to the RNA was characterized by a significantly lower association constant ( ~ 3.4×103 M-1) indicating either the external or “partially intercalated” binding mode. The addition of the europium complexes to the AK3-5-DNA system was followed by the fluorescence intensity decrease, with a magnitude of this effect being dependent on the EC structure. The observed fluorescence decrease of AK3-5 in the presence of europium complexes V7 and V9 points to the competition between the cyanine dye and antitumor drugs for the DNA binding sites. The dependencies of the AK3-5-DNA fluorescence intensity decrease vs. europium complex concentration were analyzed in terms of the Langmuir adsorption model, giving the values of the drug association constant equal to 5.4×104 M-1and 3.9×105 M-1 for the europium complexes V7 and V9, respectively. A more pronounced decrease of the AK3-5 fluorescence in the presence of V5 and V10 was interpreted in terms of the drug-induced quenching of the dye fluorescence, accompanying the competition between AK3-5 and Eu(III) complexes for the DNA binding sites. Cumulatively, the results presented here strongly suggest that AK3-5 can be effectively used in the nucleic acid studies and in the dye-drug displacement assays.

MONOCLONAL ANTIBODIES THAT RECOGNIZE Ca2+-INDUCED CONFORMER OF PROTEIN C, INDEPENDENT OF GLA RESIDUES

1987 ◽  
Author(s):  
T Sugo ◽  
S Tanabe ◽  
K Shinoda ◽  
M Matsuda
Keyword(s):  
Monoclonal Antibodies ◽  
Light Chain ◽  
Metal Binding ◽  
Binding Sites ◽  
Plasma Proteins ◽  
Protein C ◽  
The Other ◽  
Metal Binding Sites ◽  
Direct Elisa ◽  
Gla Domain

Monoclonal antibodies (MCA’s) were prepared against human protein C (PC) according to Köhler & Milstein, and those that recognize the Ca2+-dependent PC conformers were screened by direct ELISA in the presence of 2 mM either CaCl2 or EDTA. Out of nine MCAߣs thus screened, five MCA's designated as HPC-1˜5, respectively, were found to react with PC in the presence of Ca2+ but not EDTA. By SDS-PAGE coupled with Western Blotting performed in the presence of 2 mM CaCl2, we found that two MCA’s HPC-1 and 2, recognized the light chain, and two others, HPC-3 and 4, recognized the heavy chain of PC. But another MCA, HPC-5 was found to react with only non-reduced antigens. Further study showed that HPC-1 and 5 failed to react with the Gla-domainless PC, i.e. PC from which the N-terminal Gla-domain of the light chain had been cleaved off by α-chymotrypsin. However, all the other three MCA's retained the reactivity with the antigen in the presence of Ca2+ even after the Gla-domain had been removed. The binding of these MCA’s to PC in the presence of Ca2+ was found to be saturable with respect to the Ca2+ concentration and the half maximal binding for each MCA was calculated to be about 0.5+mM. Moreover, many other divalent cations such as Mg2+, Mn2+ , Ba2+, Zn2+, Co2+, Sr2+, were found to substitute for Ca2+ in inducing the metal ion-dependent but Gla-domain-independent conformer of PC.Cross-reactivity to other vitamin K-aependent plasma proteins was examined by direct ELISA; HPC-2 and 3 reacted solely to PC, but HPC-1 and 4 also reacted with prothrombin and HPC-5 with both prothrombin and factor X.These findings indicated that there are two or more metal binding sites besides the Gla-domain, possibly one in the light chain and the other(s) in the heavy chain. The presence of these metal binding sites may contribute to the unique conformer of vitamin K-dependent plasma proteins including protein C.

scholarly journals Evaluation of E-rosetting human lymphocytes with OKT11 and other monoclonal antibodies

Blood ◽  
1982 ◽  
Vol 60 (3) ◽  
pp. 795-799 ◽  
Author(s):  
SH Ip ◽  
CW Rittershaus ◽  
CC Struzziero ◽  
JA Hoxie ◽  
RA Hoffman ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Fluorescence Intensity ◽  
Binding Sites ◽  
Blood Cells ◽  
Human Lymphocytes ◽  
Immunofluorescent Staining ◽  
Intensity Data ◽  
Blood Samples ◽  
Staining Methods

Abstract Monoclonal antibody OKT11 was found to compete with sheep red blood cells for binding sites on human lymphocytes. Preincubation of lymphocytes with OKT11 eliminated E-rosette formation. In a study of 142 peripheral blood samples ranging from 1% to over 90% E-rosette- positive cells, comparison to the percent OKT11-positive cells yielded a correlation coefficient of 0.93. In normal donors, subsets of OKT11+ cells were identified using two-color immunofluorescent staining methods with OKT3, OKT4, and OKT8. On the average, approximately 13% of OKT11+ lymphocytes were OKT3- and 13% of OKT11+ lymphocytes were OKT4- and OKT8-. Based on our double antibody fluorescence intensity data, low antigen density OKT11+ lymphocytes were OKT3-. OKT4+ and OKT8+ lymphocytes in normal peripheral lymphocytes have similar OKT11 antigen density.

scholarly journals Neutralization of Human Papillomavirus with Monoclonal Antibodies Reveals Different Mechanisms of Inhibition

2007 ◽  
Vol 81 (16) ◽  
pp. 8784-8792 ◽  
Author(s):  
Patricia M. Day ◽  
Cynthia D. Thompson ◽  
Christopher B. Buck ◽  
Yuk-Ying S. Pang ◽  
Douglas R. Lowy ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Monoclonal Antibodies ◽  
Human Papillomavirus ◽  
Cell Surface ◽  
Binding Sites ◽  
Neutralizing Antibodies ◽  
Hpv Infection ◽  
Heparan Sulfate Proteoglycans ◽  
Hacat Cells ◽  
Block Association

ABSTRACT The mechanisms of human papillomavirus (HPV) neutralization by antibodies are incompletely understood. We have used HPV16 pseudovirus infection of HaCaT cells to analyze how several neutralizing monoclonal antibodies (MAbs) generated against HPV16 L1 interfere with the process of keratinocyte infection. HPV16 capsids normally bind to both the cell surface and extracellular matrix (ECM) of HaCaT cells. Surprisingly, two strongly neutralizing MAbs, V5 and E70, did not prevent attachment of capsids to the cell surface. However, they did block association with the ECM and prevented internalization of cell surface-bound capsids. In contrast, MAb U4 prevented binding to the cell surface but not to the ECM. The epitope recognized by U4 was inaccessible when virions were bound to the cell surface but became accessible after endocytosis, presumably coinciding with receptor detachment. Treatment of capsids with heparin, which is known to interfere with binding to cell surface heparan sulfate proteoglycans (HSPGs), also resulted in HPV16 localization to the ECM. These results suggest that the U4 epitope on the intercapsomeric C-terminal arm is likely to encompass the critical HSPG interaction residues for HPV16, while the V5 and E70 epitopes at the apex of the capsomer overlap the ECM-binding sites. We conclude that neutralizing antibodies can inhibit HPV infection by multiple distinct mechanisms, and understanding these mechanisms can add insight to the HPV entry processes.

scholarly journals The Bra/Brb alloantigen system on human platelets

Blood ◽  
1989 ◽  
Vol 73 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
V Kiefel ◽  
S Santoso ◽  
B Katzmann ◽  
C Mueller-Eckhardt
Keyword(s):  
Monoclonal Antibodies ◽  
Binding Sites ◽  
Gene Frequency ◽  
Family Studies ◽  
Human Platelets ◽  
Alloimmune Thrombocytopenia

Abstract Anti-Bra was first identified in four cases of neonatal alloimmune thrombocytopenia (NAIT). The antigen Bra is localized on the glycoprotein Ia/IIa complex of platelets. Anti-Bra can best be detected by a glycoprotein-specific immunoassay using monoclonal antibodies for antigen immobilization (MAIPA assay) and radioimmunoprecipitation (RIP). Recently, we have identified sera from two polytransfused patients that contain an antibody that recognizes Brb, the allele of Bra. Family studies show that both antigens are inherited as autosomal codominant characters. The gene frequency of the new allele Brb is 0.888. Approximately 2,000 anti-Bra binding sites are present on homozygous platelets and 1,000 on heterozygous platelets. Our findings provide evidence for the first polymorphism observed on the glycoprotein Ia/IIa complex. Immunization against these alloantigens is implicated in NAIT and poly-transfused patients.

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