Pairing of oligosaccharides in the Fc region of immunoglobulin G

The Fc portion of immunoglobulin G (IgG) expresses paired oligosaccharides with microheterogeneities, which are associated with efficiencies of effect or functions and with pathological states. A comparison of electrospray ion ization mass spectrometry data obtained using a variety of Fc fragments der ived from human and mouse IgG that do and do not retain the inter-chain dis ulfide bridge(s) revealed that (1) the Fc portion can be asymmetric as well as symmetric with respect to glycosylation and (2) the ratios of the indiv idual glycoforms are different from what is expected from the random pairin g. (C) 2000 Federation of European Biochemical Societies.