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Reassembly of Immunoglobulin M Heavy and Light Chains In Vitro
Author(s) -
SCHROHENLOHER R. E.,
HESTER R. B.
Publication year - 1976
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1976.tb03013.x
Subject(s) - alkylation , chemistry , immunoglobulin light chain , protein subunit , stereochemistry , biochemistry , chromatography , antibody , biology , gene , immunology , catalysis
Reduced and alleviated monoclonal IgM was fractionated into μ and light (L) chains by gel chromatography in 1N acetic acid. Equimolar mixtures of the chains formed a noncovalently bonded structure in 0.01M sodium acetate buffer, pH 4.1, that had the properties of a half subunit. The latter reassociated into a subunit‐like structure after transfer into 0.08M sodium phosphate buffer, pH 7.5. The similarity of the reconstituted IgM subunit (IgMs) to that of the native molecule was established by its physicochemical and immunochemical properties. Comparable products were obtained on reassembly of the alkylated μ and L chains from several other monoclonal IgM. The presence of active binding sites for IgG on subunits reconstituted from the chains of proteins with anti‐IgG activity further indicated correct assembly of the μ and L chains. High yields of subunit‐like products were also obtained by assembly of μ chains from one protein and L chains from another. Evidence was obtained that L chains of appropriate specificity can substitute for the homologous chain in the formation of the active site. Heterogeneous mixtures of high molecular weight products were generated from μ and L chains that were not alkylated. Reduction and alkylation demonstrated that the products represented polymers of reconstituted IgMs. Significant levels of anti‐IgG activity were detected in the polymeric IgM generated from the chains of active proteins by precipitation with aggregated IgG.