Covalent immunoglobulin assembly in vitro: reactivity of light chain covalent dimers (L2) and blocked light chain monomers.

Covalent light chain dimers (L2) and cysteine-blocked L chain monomers readily react with partially reduced heavy (H) chains. A rapid disappearance of these blocked L chain species is followed by the appearance of covalent intermediates-HL, H2, and H2L-leading to fully assembled H2L2. The mechanism of initial disulfide bond formation between heavy and light chains is disulfide interchange.