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A simple modified carbodiimide method for conjugation of small-molecular-weight compounds to immunoglobulin G with minimal protein crosslinking

1981; Elsevier BV; Volume: 116; Issue: 2 Linguagem: Inglês

10.1016/0003-2697(81)90380-8

1096-0309

Minh-Tam B. Davis, James F. Preston,

Immunodeficiency and Autoimmune Disorders

Optimal conditions for the conjugation of carboxyl groups on low molecular weight molecules to reactive amino groups on rabbit immunoglobulin G (IgG) using a modified carbodiimide reaction have been investigated. Reaction of [14C]hippuric acid with N-ethyl-N′-(dimethylaminopropyl) carbodiimide at pH 5 followed by adjustment to pH 8 and coupling with rabbit IgG resulted in the formation of hippuric acid-IgG conjugates with less than 10% intra- and intermolecular IgG crosslinking. More than 93% of the bonds linking hippuric acid to IgG were stable to hydroxylamine hydrolysis, indicating the peptide properties of these bonds. This two-step process permitted a defined number of hippuric acid moieties to be loaded onto a single IgG molecule and should provide a useful method for the conjugation of molecules containing carboxyl groups to amino groups on a variety of polypeptides.