Kinetics of recombination of heavy and light chains of a human IgG1 myeloma protein.

The recombination of alkylated H and L chains of a human myeloma protein (Jo) was studied by means of circular dichroism (CD). Marked CD changes were observed at 295 and 235 nm when H and L chains recombined. The change in the CD maximum at 235 nm was followed with time after mixing preparations of H and L chains in the pH range between 4 and 6. The recombination reaction was slow and followed second order kinetics. The observed rate constants were markedly dependent on pH. The pH dependence of the rate constant was analyzed assuming that there are two forms of H chain which are in a pH-dependent equilibrium with each other.