Kato K, Hamaguchi Y, Fukui H, Ishikawa E
Eur J Biochem. 1976 Feb 16;62(2):285-92. doi: 10.1111/j.1432-1033.1976.tb10159.x.
Rabbit immunoglobulin G (IgG) was reduced by incubating with 10 mM 2-mercaptoethylamine and then treated with excess amounts of N,N'-o-phenylenedimaleimide. As a result, maleimide residues were introduced into rabbit IgG molecules. Rabbit IgG containing maleimide residues could be coupled to beta-D-galactosidase from Escherichia coli which has sulfhydryl groups in the molecule. The resulting rabbit IgG (antibody)-enzyme complex may be useful for immunoassay of antigens. As an example, human IgG was assayed by the sandwich method using the rabbit anti-(human IgG) IgG-beta-D-galactosidase complex and amounts of human IgG as small as 3 fmoles were measurable.
