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Biomedical subjects

J D Capra

Publications and source records attributed to J D Capra.

At least 235 records · Page 13Linked to original sources
PubMed1978

Studies on the murine Ss protein: demonstration that the Ss protein is functionally the fourth component of complement.

This report describes a simple and reproducible assay for the fourth component of murine complement (C4). Utilizing this assay, experiments are described which conclusively demonstrate that the murine Ss protein (serum substance) is functional C4 and that ascitic fluid may be used as a source for isolating Ss. The evidence that Ss is functional C4 is: (i) pretreatment of mouse plasma with F(ab')2 anti-Ss completely abrogated the C4 hemolytic titer; and (ii) in the isolation of the Ss protein from ascitic fluid, Ss immunochemical activity and C4 functional activity coeluted in each step of a four-step purification procedure.

Animals↗
PubMed1978

Isolation and partial characterization of the allergen in mountain cedar pollen.

A biologically active fraction from a crude extract of mountain cedar pollen has been purified and partially chemically characterized. An ammonium bicarbonate extract of commercial defatted pollen was fractionated by G-100 Sephadex chromatography and the biologically active fraction was found to be homogeneous by polyacrylamide gel electrophoresis and N-terminal amino acid sequence analysis. The biologically active component is a 50,000 dalton protein whose N-terminal amino acid sequence is Asp--Asn--Pro--Ile--Asp. These findings provide a further purified pollen allergen for immunologic studies and the first such purified allergen having clinical significance in a limited geographic region.

Allergens↗
PubMed1978

Structural studies on protein products of murine chromosome 17. III. Partial amino acid sequence of an H-2Kq molecule.

Twenty-one of the amino terminal twenty-seven amino acid residues have been assigned in the murine H-2Kq molecule and several additional assignments and corrections have been made in both the H-2Kk and H-2Kb molecules. The study shows that 1) H-2Kk and H-Kq, which are serologically related, have an identical amino acid sequence for all twenty positions that can be compared, 2) the H-2Kk and H-2Kq molecules differ from H-2Kb at only two positions--9 and 22, and 3) the additional sequence data on the H-2Kk, -Kb, and -Kq molecules increases the already striking homology between murine and human transplantation antigens.

Amino Acid Sequence↗
PubMed1978

Structural studies on the murine IA alloantigens. II. Molecular weight characterization of the products of the I-A and I-E/C subregions.

Murine splenocytes were radiolabeled with 3H- and 14C-amino acids; the Ia alloantigens encoded by the I-A and I-E/C subregions were isolated by immunoprecipitation and analyzed for structural variation by polyacrylamide gel electrophoresis. The I-A subregion products (k, d, and b haplotypes) are composed of two polypeptides, alpha and beta, with m.w. of 34,000 and 26,000 daltons, respectively. Haplotype-associated differences in m.w. were detected in the I-E/C products of the k, r, p, and d haplotypes. The alpha and beta chains of E/Ck and E/Cr are 34,000 and 28,000 daltons, respectively; E/Cp and E/Cd molecules are composed of 31,000 and 29,000 dalton polypeptides. Thus, there is both subregion (I-A vs I-E/C) and haplotype (E/Ck, E/Cr vs E/Cd, E/Cp) associated variation in the m.w. of the Ia alloantigens. Additionally, the covalent vs noncovalent association of the Ia subunits was examined and it was found that the alpha and beta chains of both I-A and I-E/C are not covalently associated. However, the I-A alpha and beta chains tend to associate through disulfide bonds during detergent lysis; the presence of alkylating agents during cell lysis prevents this association, and only free alpha and beta chains are observed under nonreducing conditions.

Animals↗
PubMed1978

Structural studies on induced antibodies with defined idiotypic specificities. VI. Amino terminal sequences of the heavy and light chain variable regions of anti-p-azophenylarsonate antibodies from A/J mice suppressed for a cross-reactive idiotype.

Previous studies in this series have been directed toward the elucidation of the heavy and light chain variable region structures of antibodies raised in A/J mice to the p-azophenylarsonate (Ar) hapten, certain of which bear a cross-reacting idiotype. The present study concerns an analysis of anti-Ar antibodies that arise in A/J mice suppresed for a cross-reacting idiotype. The results indicate that when an idiotype is suppressed and the animal subsequently hyperimmunized, the resultant antibodies are "deviated" into different V-region subgroups, both in the heavy and light polypeptide chains. The study presents the first primary structural analysis of a humoral immune response that has been manipulated by an idiotypic reagent.

Amino Acid Sequence↗
PubMed1977

Primary structure of the variable regions of two canine immunoglobulin heavy chains.

The complete amino acid sequences of the variable regions of two canine immunoglobulin heavy chains have been determined by automated Edman degradation and found to be strongly homologous to the human VHIII subgroup. The canine sequences were identical with each other at 76 of 113 residue positions. Twenty-three of the 37 differences are located within the four hypervariable regions previously defined by the sequences of several human VHIII proteins. Forty-five of 77 framework residue positions are invariant in the seven human and two canine VHIII proteins which have been completely sequences. The canine proteins are 78% homologous to the framework of the human prototype. Phylogenetically associated residues before the first hypervariable region were confirmed and several potential phylogenetically associated residues were identified between the first and third hypervariable regions. This study represents the first complete amino acid sequences of VH regions of spontaneously occurring, nonhuman homogeneous immunoglobulins. The date demonstrate a high degree of preservation of VHIII structure in another species.

Amino Acid Sequence↗
PubMed1977

Towards a chemical definition of idiotypy.

The idiotypic determinants have been precisely located to the variable regions of immunoglobulin polypeptide chains. Both chains are generally required to express the idiotype. The major idiotypic determinants are the result of the amino acid sequence of the hypervaiable regions, although some idiotypic determinants reside outside the antibody combining site and these so called "framework idiotypes" are important markers. In my view the hypervariable regions are spatially disposed so as to present adequate antigenic stimulation, and they display enough structural heterogeneity to account for the uniqueness of the idiotype in the general population of immunoglobulin molecules. Hypervariable regions, the antibody combining site, and the idiotypic determinants thus amalgamate three formerly diverse concepts into a unified theoretical construct.

Binding Sites, Antibody↗
PubMed1977

Structural studies on induced antibodies with defined idiotypic specificities. V. The complete amino acid sequence of the light chain variable regions of anti-p-azophenylarsonate antibodies from A/J mice bearing a cross-reactive idiotype.

The complete amino acid sequence of the variable regions of light chains derived from anti-p-azophenylarsonate antibodies from A/J mice bearing a cross-reactive idiotype is reported. At least two and probably more than three distinct light chains are associated with this idiotypically characterized antibody. The antibodies have several differences in their "framework" structures but evidence is presented indicating that all three light chain hypervariable regions have a homogeneous sequence. The data are discussed in relation to the various theories of antibody diversity. In addition, the findings support the view that hypervariable regions, idiotypic determinants, and the antibody-combining site involve, to a large extent, the same molecular structures.

Amino Acid Sequence↗