title: Comparison of the amino acid sequences of the variable domains of two homogeneous rabbit antibodies to type III pneumococcal polysaccharide.
abstract: The amino acid sequences of the V (variable) regions of the H (heavy) and L (light) chains derived from rabbit antibody K-25, specific for type III pneumococci, were determined; this is the second homogeneous rabbit antibody besides antibody BS-5 whose complete sequence of the V domain has been established (Jaton, 1974d). The V regions of L chains BS-5 and K-25 (both of allotype b4) differ from each other by 19 amino acid residues; 11 of these 19 substitutions are located within the three hypervariable sections of the V region. On the basis of seven amino acid differences within the N-terminal 28 positions, it is suggested that L chain K-25 belongs to a different subgroup of rabbit K chains and L chain BS-5. H chain K-25 (allotype a2) differs from another H chain of the same allotype by one amino acid substitution within the N-terminal 70 positions in addition to interchanges occurring in the first two hypervariable sections. H chain K-25 was compared with H chain BS-5 (allotype a1) and with the known V-region rabbit sequences. Allotype-related differences between a1, a2 and a3 chains appear to occur within the N-terminal 16 positions and possibly in scattered positions throughout the V-region. In the hypervariable positions, variability between the two antibodies is remarkably more pronounced within the third hypervariable section of both H and L chains than within the first two.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis*; D007143:Immunoglobulin Heavy Chains / Q000032:analysis; D007147:Immunoglobulin Light Chains / Q000032:analysis; D066298:In Vitro Techniques; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D011817:Rabbits / Q000276:immunology; D013296:Streptococcus pneumoniae / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D011135:Polysaccharides, Bacterial