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Biomedical subjects

D Pressman

Publications and source records attributed to D Pressman.

At least 217 records · Page 12Linked to original sources
PubMed1966

Antibody molecules: discontinuous heterogeneity of heavy chains.

The heavy polypeptide chains of antibody ( and of gammaG-immnunoglobulin) molecules show discrete bands on disc electrophoresis. The same bands are present for chains from antibodies of the same or diverse specificities. Individual bands are of different intensities for chains from the different rabbits tested even if the antibodies are directed against the same hapten. The bands appear to represent classes of heterogeneous H-chains of the same size having discrete differences in mizobilities with respect to a single charge difference.

Animals↗
PubMed1966

Specificity in the combination of Fd fragments with L chains to form hapten-binding sites.

In the work reported here we have shown that light chains and Fd fragments can be separated completely in propionic acid and then recombined to form Fab fragments with antibody activity. This experiment indicates that in the recombination a correct alignment of the Fd fragments and the L chains occurs to give a competent antibody site, just as occurs with the recombination of separated heavy and light chains of the antibody; thus the Fc fragment is not required for correct alignment. Fd fragments of antibody alone show very low binding activity toward the specific hapten. As is the case for the combination of heavy and light chains, the combination of Fd fragments and light chains also requires that both components come from antibody from the same rabbit in order to give binding sites. When they are derived from different rabbits producing antibody against the same antigen, they still give Fab fragments as shown by immunoelectrophoresis but do not have competent binding sites. An important observation is that the subunits of the papain digest fractions, Fab(I) and Fab(II), have the capacity to cross-combine to form active Fab fragments with competent binding sites. Fd(I) from Fab(I) combines with L(II) chains from Fab(II) to give the composite (Fd(I)-L(II)) with good binding activity. Likewise, the composite (Fd(II)-L(I)) has good binding activity. The composites from the two types of antibody molecules yielding different Fab fragments have antibody activity although heretofore these molecules have appeared to be different on the bases of chromatography and amino acid analysis. There is also a preferential combination of the Fd fragments to combine with the correct L fragments to give binding sites since this combination takes preference over the combination of Fd fragments of antibody with light chains of normal globulin (or of light chains of antibody with Fd fragments of normal globulin).

Animals↗
PubMed1966

Isolation of rabbit IgA antihapten antibody and demonstration of skin-sensitizing activity in homologous skin.

Multiple antibody components of rabbit antisera against p-azobenzenearsonate (R(p)) were studied with respect to their globulin nature and skin-sensitizing activity. IgA antibody was characterized by isolating two IgA-rich fractions from a specifically purified antibody preparation. Examination of these fractions showed that IgA antibodies existed in two molecular forms, one with a sedimentation constant of 7S and the other 9S. Skin-sensitizing activity was examined by a P-K type test and a PCA test with R(p)-rabbit serum albumin in homologous (rabbit) species. Only the 7S but not 9S IgA antibody sensitized rabbit skin. IgM antibody showed no activity and IgG antibody showed very low activity. In contrast, only IgG antibody was active in the P-K type test to sensitize a heterologous species (guinea pig). None of the antibodies of other classes showed sensitizing activity in heterologous skin. The 7S IgA antibody lost its sensitizing activity upon reduction and alkylation, although no change in its molecular size could be observed. The loss of sensitizing activity was not due to the destruction of antigen-binding activity since the treated 7S IgA antibody retained this activity as shown by radioimmunoelectrophoresis and by binding to the specific immunoadsorbent. The 9S IgA antibody was more resistant to these treatments than the IgM antibody and showed no indication of dissociation. The treated 9S IgA also retained antigen-binding activity. Both the P-K type and PCA reactions were considerably stronger when the interval between injections of antibody and antigen was 24 hr rather than 4 to 5 hr.

Animals↗
PubMed1965

Preferential recombination of antibody chains to form effective binding sites.

The recovery of hapten-binding activity by a mixture of H and L polypeptide chains of the whole gammaG-immunoglobulin fraction from rabbit anti-p-azobenzenearsonate (Rp) serum is almost as great as that by a mixture of H and L chains from specifically purified Rp antibody. Random combination among the H and L chains from the anti-Rp antibodies and the normal gammaG-immunoglobulin present would result in little recovery of hapten-binding activity. This suggests a preferential recombination of H and L chains from antibody. Mixtures of H or L chains from anti-p-azobenzoate (Xp) antibody and the complementary chains from antibody-depleted gammaG-immunoglobulin show little hapten-binding. When anti-Xp antibody H chains are added to mixtures of one equivalent of anti-Xp L chain and increasing amounts of non-specific L chain, the hapten-binding by the mixtures decreases, but not as much as if the H chains combined with the L chains randomly. Hapten was not present during these recombination procedures. These data indicate that in the cases of anti-Xp and of anti-Rp antibodies, there is a selective combination between those H and L chains which give effective hapten binding regions.

Animals↗