Polypeptide chains of immunoglobulins from the smooth dogfish (Mustelus canis).

The 17S and 7S immunoglobulins of the smooth dogfish, Mustelus canis, have been characterized with respect to molecular weights, chain structure, amino acid composition, and carbohydrate content. The 17S protein had a molecular weight of 982,000; that of the 7S protein was 198,000. Both proteins had similar amino acid compositions and a carbohydrate content of approximately 8 percent.

Phylogenetic origins of antibody structure. II. Immunoglobulins in the primary immune response of the bullfrog, Rana catesbiana.

The anuran amphibian, Rana catesbiana, has been found to possess at least two kinds of immunoglobulins corresponding to gammaG- and gammaM-classes. These classes have the same chain structures as those of their counterparts in higher animal species. Light chains of both immunoglobulins had molecular weights of 20,000.

Phylogenetic origins of antibody structure. I. Multichain structure of immunoglobulins in the smooth dogfish (Mustelus canis).

The elasmobranch Mustelus canis has been shown to produce antibodies to Limulus hemocyanin. The serum of both normal and immunized M. canis contains immunoglobulins having sedimentation coefficients of approximately 7S and 17S.

CORROBORATION OF RECENT MODELS OF THE GAMMA-G IMMUNOGLOBULIN MOLECULE.

The relationships between the polypeptide chains of gammaG immunoglobulin and fragments of the molecule produced by papain and pepsin have been investigated. Specific procedures were employed including peptide mapping of tryptic hydrolysates and analysis of molecules reconstituted from chains labeled with different iodine isotopes. By these means, the Fab fragment was shown unequivocally to consist of the light chain and a portion of the heavy chain, the Fd fragment.

RECONSTITUTION OF ANTIPHAGE ANTIBODIES FROM L AND H POLYPEPTIDE CHAINS AND THE FORMATION OF INTERSPECIES MOLECULAR HYBRIDS.

Reconstitution of phage-neutralizing activity was observed after admixture of separated L and H polypeptide chains of purified antibodies obtained from single sheep or guinea pigs and directed against f1 and f2 phages. Hybrid mixtures of complementary chains of antiphage antibodies and gamma-globulins of the same animal showed less activity than the homologous mixtures of chains from antibodies of the same specificity. 7S interspecies molecular hybrids could be formed between L or H chains of sheep gamma-globulins and the complementary chains of guinea pig gamma-globulins.

PROTEIN-PROTEIN INTERACTIONS AMONG L POLYPEPTIDE CHAINS OF BENCE-JONES PROTEINS AND HUMAN GAMMA-GLOBULINS.

The L polypeptide chains of certain Bence-Jones proteins of group I have been found in three forms: monomers of molecular weight of about 20,000, dimers which monomerize in dissociating solvents, and dimers which are stable in such solvents. The L polypeptide chains of some Bence-Jones proteins of group II were found to occur naturally only as stable dimers. The L chains of normal human gamma-globulin have been obtained in a reduced unalkylated form, and a fraction of these chains was found to form stable dimers under oxidizing conditions.

RECONSTITUTION OF 7S MOLECULES FROM L AND H POLYPEPTIDE CHAINS OF ANTIBODIES AND GAMMA-GLOBULINS.

Admixture of separated L and H polypeptide chains of 7S gamma-globulins under appropriate conditions has been found to result in the reconstitution of 7S molecules. The chains were mixed in 0.5 N propionic acid and when dialyzed into neutral aqueous buffers interacted to form reconstituted material in greater than 30 per cent yield.

STUDIES ON HUMAN ANTIBODIES. I. STARCH GEL ELECTROPHORESIS OF THE DISSOCIATED POLYPEPTIDE CHAINS.

Specific precipitates and purified human antibodies were reduced and alkylated and subjected to starch gel electrophoresis in 8 M urea to dissociate and separate the L and H polypeptide chains. Dissociated antibodies to dextran, levan, teichoic acid, blood group A substance, and tetanus toxoid showed sharp bands corresponding to L polypeptide chains. The patterns differed for antibodies of different specificities.