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J J Marchalonis

Publications and source records attributed to J J Marchalonis.

At least 235 records · Page 13Linked to original sources
PubMed1971

Enzymic iodination. A probe for accessible surface proteins of normal and neoplastic lymphocytes.

1. Radioactive iodide was covalently bound to living cells from normal mouse spleen and a variety of lymphoid tumours by a system consisting of lactoperoxidase, hydrogen peroxide and iodide. 2. About 3x10(5)-6x10(5) molecules of [(125)I]iodide/cell could be incorporated without affecting cell viability. 3. Electron-micrographic radioautography showed that the radioactive label was associated with the outer surfaces of the cells. 4. Radioiodinated proteins were solubilized in 9m-urea-0.2m-mercaptoethanol and analysed by gel-filtration and disc electrophoresis. 5. Comparison of distinct tumour lines by disc electrophoresis showed qualitative and quantitative differences in protein distribution patterns.

Animals↗
PubMed1969

An enzymic method for the trace iodination of immunoglobulins and other proteins.

1. A method is described for the trace iodination of immunoglobulins and other serum proteins by a system consisting of lactoperoxidase, hydrogen peroxide and iodide. 2. gammaG immunoglobulin that had been labelled to a specific radioactivity of 5muc/mug. by use of carrier-free [(125)I]iodide gave no evidence of denaturation when analysed by electrophoresis and density-gradient ultracentrifugation. 3. Tryptic hydrolysis and peptide ;mapping' of a completely characterized peptide radioiodinated by this method showed that the [(125)I]iodide was bound to tyrosyl residues. 4. Proteins differ in their susceptibility to iodination by this method. Human gammaG immunoglobulin, for example, is iodinated more than ten times as readily as is human alpha(2)-macroglobulin under the same conditions. 5. Lactoperoxidase catalyses the iodination of proteins much more readily than does horseradish peroxidase.

Animals↗
PubMed1968

Phylogenetic origins of antibody structure. 3. Antibodies in the primary immune response of the sea lamprey, Petromyzon marinus.

The sea lamprey, Petromyzon marinus, has been found to produce specific antibodies after immunization with bacteriophage f2. Antibody activity is localized in 6.6S and 14S fractions of lamprey serum. The 6.6S antibodies were purified by a combination of zone electrophoresis, ion exchange chromatography, and gel filtration. Antigenic analysis of the 6.6S antibodies showed them to be free of other serum proteins and antigenically similar or identical to the 14S fraction. Evidence has been obtained which suggests that the 6.6S immunoglobulins consist of light components (molecular weight 25,000) and heavy components (molecular weight 70,000). In the immunoglobulin, these polypeptides appear to be linked via weak interactions but not by interchain disulfide bonds. Molecular weight analyses support the view that the chains can undergo concentration-dependent dissociation in aqueous solutions. Amino acid analyses showed that the compositions of the light and heavy components were similar and that aspartic acid or asparagine was the predominant amino terminal residue. Starch gel electrophoresis indicated that the subunits of lamprey antibodies are diffusely heterogeneous. The heavy chain mobility corresponded to that of micro-chains and resembled that of heavy chains of shark and sting ray immunoglobulins. In the course of the fractionation a 46S natural hemagglutinin composed of lower molecular weight subunits was isolated. This hemagglutinin did not resemble the lamprey immunoglobulin although it had a similar zone electrophoretic mobility in the beta-region. These studies are consistent with the hypothesis that micro-chains were the earliest of the heavy chain classes to emerge and further support the view that the multichain structure of immunoglobulins is a fundamental feature of antibody molecules.

Animals↗
PubMedDate not supplied

Recognition of defined epitopes by affinity-purified anti-immunoglobulin fab autoantibodies isolated from HIV-infected humans.

Infection of humans with HIV-1 has previously been independently shown to result in the generation of autoantibodies (AAbs) reactive with immunoglobulin Fab fragments (Heidelberg), and with autoantibodies to T-cell receptors (TCRs) (Tucson). Here, we carry out epitope mapping studies of affinity-purified AAbs to Fab fragments prepared from individual HIV-positive patients for their capacity to bind recombinant constructs and peptide-defined epitopes modeling TCR and Ig light chains. Some affinity-purified autoantibodies reacted strongly with TCRs expressed by intact T-cells, and recombinant Valpha/Vbeta constructs as well as with certain synthetic peptide epitopes. The binding reactions of affinity-purified AAbs of individual patients were distinct, and the AAb preparations consisted of populations of polyclonal lgs as reflected in specificity and isotype. AAb pools from individual patients all bound particular regions of TCR and Ig chains defined by comprehensive peptide synthesis including the CDR1 and Fr3 segments of the variable domains and the joining segment/switch peptide. In addition, other reactivities to restricted regions of alpha, beta and lambda light chains were documented. These results substantiate the cross-reactivity of TCR and Ig-Fab determinants, and are consistent with the hypothesis that autoantibodies arising as a consequence of HIV infection can have an immunomodulatory role.

Amino Acid Sequence↗
PubMedDate not supplied

Exquisite specificity and peptide epitope recognition promiscuity, properties shared by antibodies from sharks to humans.

This review considers definitions of the specificity of antibodies including the development of recent concepts of recognition polyspecificity and epitope promiscuity. Using sets of homologous and unrelated peptides derived from the sequences of immunoglobulin and T cell receptor chains we offer operational definitions of cross-reactivity by investigating correlations of either identities in amino acid sequence, or in hydrophobicity/hydrophilicity profiles with degree of binding in enzyme-linked immunosorbent assays. Polyreactivity, or polyspecificity, are terms used to denote binding of a monoclonal antibody or purified antibody preparation to large complex molecules that are structurally unrelated, such as thyroglobulin and DNA. As a first approximation, there is a linear correlation between degree of sequence identity or hydrophobicity/hydrophilicity and antigenic cross-binding. However, catastrophic interchanges of amino acids can occur where changing of one amino acid out of 16 in a synthetic peptide essentially eliminates binding to certain antibodies. An operational definition of epitope promiscuity for peptides is the case where two peptides show little or no identity in amino acid sequence but bind strongly to the same antibody as shown by either direct binding or competitive inhibition. Analysis of antibodies of humans and sharks, the two most divergent species in evolution to express antibodies and the combinatorial immune response, indicates that the capacity for both exquisite specificity and epitope recognition promiscuity are essential conserved features of individual vertebrate antibodies.

Amino Acid Sequence↗
PubMedDate not supplied

Antibody production in sharks and humans: a role for natural antibodies.

Although gene segments specifying Igs of all vertebrates show clear homology, their arrangements differ markedly, thereby suggesting that the mechanisms for the generation of diversity and for the regulation of gene expression may be quite distinct. In the sandbar shark, light chain gene segments are distributed as apparently independent clusters consisting of V, J, and C elements that require rearrangement for expression. The usual distance between V and C in the clusters is 3 kb but larger clusters occur. The V, J, and C elements are clearly homologous to those of human lambda chains. Shark Igs resemble mammalian IgM in structure and gene similarity. IgM may comprise as much as 50% of serum proteins in the shark. By contrast, IgM in humans comprises less than 5%. Human autoantibodies usually are IgM. These show little dependence on thymic function for expression and tend to increase with age. We have carried out a study of the capacity of Igs of unimmunized sharks and people (normals and patients suffering from autoimmune diseases) to react against a panel of antigens, including those usually considered autoantibodies, such as thyroglobulin and single-stranded DNA. Sharks and humans possess IgM antibodies that react with thyroglobulin and ssDNA. Affinity-purified natural shark antibodies to thyroglobulin or ssDNA constitute small fractions of total IgM. They illustrate extensive cross-reactivity comparable to that shown by polyspecific IgM autoantibodies produced by human B cells (CD5+) that appear early in ontogeny.

Amino Acid Sequence↗