[Binding of polypeptide chains of IGG-determining factors using recombination of isolated chains]

The authors, after autologous and heterologous recombination of alkylated and nonalkylated H and L chains of IgG myeloma proteins belonging to different subclasses, studied the sensitivity to papain of reassociated molecules. They found that the coupling of chains by noncovalent bonds is not sufficient for the restoration of papain resistance characteristic of subclasses IgG 2 and IgG 4 and that disulfide bridges between the chains are also necessary for this. The results obtained by them for the heterologous recombination of chains demonstrate the importance of heavy chains to the development of molecular conformation, throwing light upon the possible role of the variable part of L chains in this particular respect. They also discussed the possibility of preferred linkage of light and heavy chains obtained from IgG molecules belonging to the same subclasses and showed that those heterologous chains which are derived from IgG myeloma proteins belonging to the same subclasses preferably link up with each other. The authors, in the light of the results obtained by them, then discuss the importance of "randomness" and "nonrandomness" in the coupling of H and L chains.