Goat immunolobulin G. Peptide chains and terminal residues.

Goat immunoglobulin G (IgG) was isolated and characterized. The molecular weights of the IgG and its heavy chains and light chains were found to be 144000, 53600 and 23000 respectively. The light chain corresponds to human L type as was shown by the absence of C-terminal S-carboxymethylcysteine and its high content of N-terminal pyrrolid-2-one-5-carboxylic acid (PCA). The major C-terminal residue of the light chain was serine and the major N-terminal dipeptide was PCA-Ala (0.6mole/mole). The major C-terminal residue of the heavy chain was glycine and the N-terminal sequence of the heavy chain is PCA-Val-Gln. This tripeptide was obtained in a 70% yield.