The recombination of dimers of immunoglobulin peptide chains

Abstract

1. Both the gamma and light peptide chains of human pooled and myeloma immunoglobulin G can be prepared as non-aggregating dimers at pH5.4 in 4mm-sodium acetate buffer. The dimeric state is maintained by non-covalent bonds, since the formation of interchain disulphide bonds was prevented by alkylation of the thiol groups. In the case of the light chains there is some evidence that the dimers are in equilibrium with a small amount of monomer. 2. When such dimers of the gamma and light chains are mixed at pH5.4 in 4mm-sodium acetate buffer they combine rapidly, yielding a product that resembles the original immunoglobulin G in its physicochemical and antigenic properties. However, the original optical rotatory dispersion spectrum was regained only with the homogeneous myeloma protein. The recombined pooled immunoglobulin G had a spectrum slightly different from the original, suggesting that at least some of the recombinant molecules had not regained native conformations. 3. Dimers of gamma chains stabilized by interchain disulphide bonds were able to recombine with light chains. However, light chains stabilized in the dimeric state by interchain disulphide bonds would not combine with gamma chains. 4. The chains of rabbit immunoglobulin G behave similarly to the human chains in this system, apart from the alkylated light chains showing clearer evidence of monomeric components.

Self-association of human immunoglobulin kappa I light chains: role of the third hypervariable region.

“…For instance, it can be calculated that a KD of 102 M-1 would allow 10% of the covalent-linked chains to be unassociated. This could explain the discrepancies observed in reconstitution studies of IgG molecules (30,31). When a low-KD light chain is used (31), a substantial portion of the disulfidebonded light chains may be available for association with the heavy chain, which would not be the case if the light chains were tightly bound.…”

A fragment corresponding to the CH2 region of immunoglobulin G (IgG) with complement fixing activity

“…Human IgGlmyeloma proteins were isolated and Fc fragments prepared from them by plasmin digestion following previously published methods [7,8]. Trypsin (Type XI-DCC treated) and soybean tryp sin inhibitor (Type 1-S) were obtained from Sigma Chemical Co. Antisera to Fc were prepared by absorbing rabbit antiserum to T-chain with Fab fragment.…”

Independent Folding of the Variable and Constant Halves of a Lambda Immunoglobulin Light Chain

“…An interesting feature of the ORD spectrum of the variable half, lacking from the spectrum of the constant part, is the indication of a small Cotton effect at about 240 nm. A similar Cotton effect is given also by intact IgG, by the Fab portion of IgG (16), and by the y-chain, apparently its Fd part (17,18). The structural entity giving rise to this effect is not known (19).…”