scholarly journals Conversion of proinsulin to insulin occurs coordinately with acidification of maturing secretory vesicles.

1986 ◽  
Vol 103 (6) ◽  
pp. 2273-2281 ◽  
Author(s):  
L Orci ◽  
M Ravazzola ◽  
M Amherdt ◽  
O Madsen ◽  
A Perrelet ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Islet Cells ◽  
Protein A ◽  
Secretory Vesicle ◽  
Average Density ◽  
Secretory Vesicles ◽  
Gold Particles ◽  
Single Polypeptide Chain ◽  
Igg Binding ◽  
Single Polypeptide

Proinsulin is a single polypeptide chain composed of the B and A subunits of insulin joined by the C-peptide region. Proinsulin is converted to insulin during the maturation of secretory vesicles by the action of two proteases and conversion is inhibited by ionophores that disrupted intracellular H+ gradients. To determine if conversion of prohormone to hormone actually occurs in an acidic secretory vesicle, cultured rat islet cells were incubated in the presence of 3-(2,4-dinitroanilino)-3' amino-N-methyldipropylamine (DAMP), a basic congener of dinitrophenol that concentrates in acidic compartments and is retained there after aldehyde fixation. The cells were processed for indirect protein A-gold colocalization of DAMP, using a monoclonal antibody to dinitrophenol, and proinsulin, using a monoclonal antibody that exclusively reacts with the prohormone. The average density of DAMP-specific gold particles in immature secretory vesicles that contained proinsulin was 71/micron 2 (18 times cytoplasmic background), which indicated that this compartment was acidic. However, the density of DAMP-specific gold particles in the insulin-rich mature secretory vesicle averaged 433/micron 2. This suggests that although proinsulin conversion occurs in an acidic compartment, the secretory vesicles become more acidic as they mature. Since the concentration of anti-proinsulin IgG binding in secretory vesicles is inversely proportional to the conversion of proinsulin to insulin, we were able to determine that maturing secretory vesicles had to reach a critical pH before proinsulin conversion occurred.

scholarly journals Immunoelectron microscopic localization of an oviductal antigen in hamster zona pellucida by use of a monoclonal antibody.

1988 ◽  
Vol 36 (11) ◽  
pp. 1441-1447 ◽  
Author(s):  
F W Kan ◽  
S St-Jacques ◽  
G Bleau
Keyword(s):  
Monoclonal Antibody ◽  
Zona Pellucida ◽  
Preimplantation Embryo ◽  
Protein A ◽  
Cumulus Cells ◽  
Gold Particles ◽  
Antigenic Sites ◽  
Cumulus Oophorus ◽  
Entire Thickness ◽  
Immunocytochemical Method

The zona pellucida is an extracellular matrix of glycoproteins which surrounds the mammalian oocyte and preimplantation embryo. We have recently developed monoclonal antibodies against oviductal zona pellucida of the golden hamster. We applied the post-embedding immunocytochemical method using a monoclonal antibody (IgGl,k) to determine the precise location of antigenic sites in the cumulus oophorus complex of the superovulated hamster. By applying the high-resolution protein A-gold technique, we demonstrated that the sites of immunoreactivity were exclusively in the zona pellucida encompassing the oocyte. Other structures within the oocyte and neighboring cumulus cells were not labeled by gold particles. Moreover, gold particles were evenly distributed throughout the entire thickness of the zona pellucida, indicating that this extracellular layer is at least in part made up of an antigen recognized by the monoclonal antibody that is uniformly distributed in the zona matrix.

scholarly journals The detection of substructures within proteoglycan molecules. Electron-microscopic immuno-localization with the use of Protein A-gold

1987 ◽  
Vol 247 (2) ◽  
pp. 267-276 ◽  
Author(s):  
J K Sheehan ◽  
A Ratcliffe ◽  
K Oates ◽  
T E Hardingham
Keyword(s):  
Monoclonal Antibody ◽  
Chondroitin Sulphate ◽  
Polyclonal Antibodies ◽  
Protein A ◽  
Electron Microscopic ◽  
Keratan Sulphate ◽  
Gold Particles ◽  
Protein Core ◽  
Gold Labelling ◽  
Chondroitin Ac Lyase

Proteoglycan monomers from pig laryngeal cartilage were examined by electron microscopy with benzyldimethylalkylammonium chloride as the spreading agent. The proteoglycans appeared as extended molecules with a beaded structure, representing the chondroitin sulphate chains collapsed around the protein core. Often a fine filamentous tail was present at one end. Substructures within proteoglycan molecules were localized by incubation with specific antibodies followed by Protein A-gold (diameter 4 nm). After the use of an anti-(binding region) serum the Protein A-gold (typically one to three particles) bound at the extreme end of the filamentous region. A small proportion of the labelled molecules (10-15%) showed the presence of gold particles at both ends. A monoclonal antibody specific for a keratan sulphate epitope (MZ15) localized a keratan sulphate-rich region at one end of the proteoglycan, but gold particles were not observed along the extended part of the protein core. This distribution was not changed by prior chondroitin AC lyase digestion of the proteoglycan. Localization with a different monoclonal antibody to keratan sulphate (5-D-4) caused a change in the spreading behaviour of a proportion (approx. 20%) of the proteoglycan monomers that lost their beaded structure and appeared with the chondroitin sulphate chains projecting from the protein core. In these molecules the Protein A-gold localized antibody (5-D-4) along the length of the protein core whereas in those molecules with a beaded appearance it labelled only at one end. Labelling with either of the monoclonal antibodies was specific, as it was inhibited by exogenously added keratan sulphate. The differential localization achieved may reflect structural differences within the proteoglycan population involving keratan sulphate and the protein core to which it is attached. The results showed that by this technique substructures within proteoglycan molecules can be identified by Protein A-gold labelling after the use of specific monoclonal or polyclonal antibodies.

Studies on the primary structure and antigenic determinants of pilin isolated from Pseudomonas aeruginosa K

1985 ◽  
Vol 63 (4) ◽  
pp. 284-291 ◽  
Author(s):  
Parimi A. Sastry ◽  
Joyce R. Pearlstone ◽  
Lawrence B. Smillie ◽  
William Paranchych
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Protein A ◽  
Disulfide Bridge ◽  
Polyclonal Antiserum ◽  
Antigenic Determinants ◽  
Enzyme Linked Immunosorbent Assay ◽  
Peptide Fragments ◽  
Single Polypeptide Chain ◽  
Rabbit Polyclonal Antiserum ◽  
Single Polypeptide

The complete amino acid sequence of Pseudomonas aeruginosa K (PAK) pilin was determined using a combination of automated and manual Edman degradation techniques. Suitable peptides were derived from cyanogen bromide, tryptic, chymotryptic, peptic, thermolytic, and citraconylated tryptic cleavages of unmodified or carboxymethylated pilin. The protein, a single polypeptide chain, has N-methylphenylalanine at the NH2-terminus, a total of 144 residues, a molecular weight of 15 013, and an equal number of acid and basic amino acids. The NH2-terminal region (residues 1–43) is very hydrophobic with only three charged residues, suggesting a possible role in subunit–subunit interaction. The two half-cystines, residues 129 and 142, are shown to be linked through a disulfide bridge in the native protein. To delineate the antigenic regions of pilin, the protein was cleaved at Arg-30, Arg-53, and Arg-120 to produce peptide fragments cTI (residues 1–30), cTII (residues 31–53), cTIII (residues 54–120), and cTIV (residues 121–144). cTIII and cTIV were further degraded into several subfragments. The purified peptides were subjected to immunological analysis using direct and competitive enzyme-linked immunosorbent assay procedures. A major antigenic determinant was delineated in a region of the protein encompassing residues 82–101. Three other epitopes were also identified, but reacted with only minor amounts of antibody in the rabbit polyclonal antiserum.

scholarly journals Specific pancreatic beta-cell surface antigens recognized by a xenogenic antiserum.

1982 ◽  
Vol 94 (2) ◽  
pp. 472-477 ◽  
Author(s):  
T Dyrberg ◽  
S Baekkeskov ◽  
A Lernmark
Keyword(s):  
Cell Surface ◽  
Beta Cells ◽  
Islet Cell ◽  
Islet Cells ◽  
Protein A ◽  
Cell Suspensions ◽  
Nmri Mouse ◽  
Mouse Islet ◽  
Gold Particles ◽  
Spleen Lymphocytes

An antiserum (R4) from a rabbit immunized with suspensions of C57BL/61 ob/ob mouse islet cells contains antibodies which in a 125I-protein A radioligand assay can be demonstrated to bind to single cell suspensions of normal Naval Medical Research Institute (NMRI) mouse islet cells. The binding of 125I-protein A to islet cells was about four times that of normal rabbit serum (NRS) after incubation at a 1/600 dilution of R4 antiserum quantitatively absorbed to mouse spleen lymphocytes (R4A antiserum) and hepatocytes. Subsequent absorption of the R4A antiserum to islet cells significantly reduced the binding of 125I-protein A to islet cells incubated with the doubly absorbed serum. Immunoprecipitation of radiolabeled islet cell lysates followed by SDS polyacrylamide gel electrophoresis and autoradiography suggested that the R4A antiserum recognized a Mr 40,000 glycoprotein. This glycoprotein was not detected in spleen lymphocytes. Electron microscope detection of gold-protein A complexes suggested that the binding of islet cell surface antibodies was cell specific. islet cell suspensions incubated with R4A antiserum and gold-protein A showed that 86 +/- 3 gold particles were bound per 100 beta-cells (mean +/- SE for six experiments). In contrast, the number of gold particles per 100 endocrine non-beta-cells was 8 +/- 1 which was similar to the number achieved with NRS (3 +/- 1) on all endocrine islet cells. Our observations suggest that the pancreatic islet cells, in particular the beta-cells, express a specific antigen.

Partial Inhibition of Platelet Aggregation and Fibrinogen Binding by a Murine Monoclonal Antibody to GPIIIa: Requirement for Antibody Bivalency

1994 ◽  
Vol 72 (06) ◽  
pp. 964-972 ◽  
Author(s):  
Jeffery L Kutok ◽  
Barry S Coller
Keyword(s):  
Monoclonal Antibody ◽  
Platelet Aggregation ◽  
Murine Monoclonal Antibody ◽  
Platelet Glycoprotein ◽  
Igg Antibody ◽  
Surface Receptors ◽  
Partial Inhibition ◽  
Fibrinogen Binding ◽  
Igg Binding ◽  
Agonist Concentration

SummaryWe produced a murine monoclonal antibody, 7H2, and localized its epitope to one or more small regions on platelet glycoprotein (GP) Ilia. 7H2-IgG and 7H2-F(ab’)2 completely inhibit platelet aggregation and fibrinogen binding at low agonist concentrations, but only partially inhibit aggregation and fibrinogen binding at high agonist concentrations; 7H2-Fab has no effect on aggregation or fibrinogen binding at any agonist concentration. 7H2-IgG binds to the entire platelet population as judged by flow cytometry. At near saturating concentrations, ∼40,000 7H2-IgG antibody molecules bind per platelet. In contrast, ∼80,000 7H2 Fab molecules bind per platelet, suggesting that 7H2-IgG binding is bivalent. 7H2 was unable to inhibit fibrinogen binding to purified, immobilized GPIIb/IIIa. These data indicate that the bivalent binding of 7H2 to GPIIIa is required for its partial inhibition of fibrinogen binding to platelets, perhaps through dimerization of GPIIb/IIIa surface receptors (or more complex GPIIb/IIIa redistribution triggered by 7H2 binding) resulting in limited accessibility of fibrinogen to its binding site(s).

Assay for islet cell antibodies. Protein A--monoclonal antibody method

Diabetes ◽  
1985 ◽  
Vol 34 (3) ◽  
pp. 300-305 ◽  
Author(s):  
S. Srikanta ◽  
A. Rabizadeh ◽  
M. A. Omar ◽  
G. S. Eisenbarth
Keyword(s):  
Monoclonal Antibody ◽  
Islet Cell ◽  
Protein A ◽  
Islet Cell Antibodies ◽  
Antibody Method

Evaluation of the Efficiency of Protein A Affinity Chromatography to Purify a Monoclonal Antibody for Cancer Treatment and its Purity Analysis

2020 ◽  
Vol 7 (2) ◽  
pp. 121-133
Author(s):  
Ayesha Akhtar ◽  
Shivakumar Arumugam ◽  
Shoaib Alam
Keyword(s):  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Affinity Chromatography ◽  
Protein A ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
High Yield ◽  
Staphylococcal Protein A ◽  
Purification Step ◽  
Purity Analysis

Background:: Protein A affinity chromatography is often employed as the most crucial purification step for monoclonal antibodies to achieve high yield with purity and throughput requirements. Introduction:: Protein A, also known as Staphylococcal protein A (SPA) is found in the cell wall of the bacteria staphylococcus aureus. It is one of the first discovered immunoglobulin binding molecules and has been extensively studied since the past few decades. The efficiency of Protein A affinity chromatography to purify a recombinant monoclonal antibody in a cell culture sample has been evaluated, which removes 99.0% of feed stream impurities. Materials and Method:: We have systematically evaluated the purification performance by using a battery of analytical methods SDS-PAGE (non-reduced and reduced sample), Cation Exchange Chromatography (CEX), Size-exclusion chromatography (SEC), and Reversed phased-Reduced Chromatography for a CHO-derived monoclonal antibody. Results and Discussion:: The analytical test was conducted to determine the impurity parameter, Host Cell Contaminating Proteins (HCP). It was evaluated to be 0.015ng/ml after the purification step; while initially, it was found to be 24.431ng/ml. Conclusion:: The tests showed a distinct decrease in the level of different impurities after the chromatography step. It can be concluded that Protein A chromatography is an efficient step in the purification of monoclonal antibodies.

scholarly journals Single Chain Variable Fragment Fused to Maltose Binding Protein: A Modular Nanocarrier Platform for the Targeted Delivery of Antitumorals

2021 ◽  
Author(s):  
Francisco J. Reche-Perez ◽  
Simona Plesselova ◽  
Eduardo De los Reyes-Berbel ◽  
Mariano Ortega-Muñoz ◽  
F. Javier Lopez-Jaramillo ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Targeted Delivery ◽  
Specific Binding ◽  
Protein A ◽  
Antibody Fragments ◽  
Single Chain Variable Fragment ◽  
Single Chain ◽  
Binding Properties ◽  
Single Chain Variable Fragments ◽  
Selective Delivery

The use of the specific binding properties of monoclonal antibody fragments such as single-chain variable fragments (ScFv) for the selective delivery of antitumor therapeutics for cancer cells is attractive due...

Debranching enzyme from rabbit skeletal muscle; Evidence for the location of two active centres on a single polypeptide chain

FEBS Letters ◽  
1975 ◽  
Vol 58 (1-2) ◽  
pp. 181-185 ◽  
Author(s):  
Edna J. Bates ◽  
Gillian M. Heaton ◽  
Carol Taylor ◽  
John C. Kernohan ◽  
Philip Cohen
Keyword(s):  
Skeletal Muscle ◽  
Polypeptide Chain ◽  
Rabbit Skeletal Muscle ◽  
Debranching Enzyme ◽  
Single Polypeptide Chain ◽  
Single Polypeptide ◽  
Active Centres
Sign in / Sign up

Export Citation Format

Share Document