title: Amino acid sequence of the N-terminal 139 residues of light chain derived from a homogeneous rabbit antibody.
abstract: The amino acid sequence of the N-terminal 139 residues of the L (light) chain derived from a homogeneous rabbit antibody (designated BS-1) to type III pneumococci was determined. A combination of methods involving tryptic cleavage restricted to the 2 arginine residues of the molecule and mild acid hydrolysis of a labile peptide bond between the V (variable) and C (constant) regions of the L chain (Fraser et al., 1972) allowed the isolation of two large peptides comprising the entire V region (residues 1-109); these peptides were suitable for automated Edman degradation. The complete sequence analysis of the V region was carried out with only 4mumol of L chain. This material was homogeneous, although minor variant sequences, if present at the 10% value, would not have been detected. The L chain contains 3 intrachain disulphide bridges, whose pairing was established by diagonal electrophoresis: there is one V-region bridge between positions 23 and 88 and one C-region bridge between positions 134 and 194; the third one connects V and C domains between positions 80 and 171. When compared with the basic sequence of human kappa chains, rabbit L chain BS-1 appears to be more similar to the V(KI) prototype sequence than to V(KII) or V(KIII) sequences, where V(KI), V(KII) and V(KIII) represent subgroups I, II and III respectively of V regions of kappa light chains. The V regions of rabbit heavy and light chains are homologous to each other. The presence of two clusters of 3 glycine residues in positions 94-96 and 99-101 respectively is remarkable. Residues 94-96 may be related to antibody complementarity whereas residues 99-101 function probably as a pivot permitting the combining region of the L chain to make optimal contact with the antigenic determinant (Wu & Kabat, 1970).
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000812:Anhydrides; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis*; D001120:Arginine; D001322:Autoanalysis; D002250:Carbon Radioisotopes; D003956:Dialysis; D004220:Disulfides; D004590:Electrophoresis, Paper; D000939:Epitopes; D005998:Glycine; D006868:Hydrolysis; D007128:Immunoglobulin Fragments / Q000032:analysis*; D008298:Maleates; D011817:Rabbits / Q000276:immunology; D013296:Streptococcus pneumoniae / Q000276:immunology; D014357:Trypsin
chemical_list: D000596:Amino Acids; D000812:Anhydrides; D000907:Antibodies, Bacterial; D002250:Carbon Radioisotopes; D004220:Disulfides; D000939:Epitopes; D007128:Immunoglobulin Fragments; D008298:Maleates; D001120:Arginine; D014357:Trypsin; D005998:Glycine