In principle, any protein can be used as a carrier for the production of bioconjugates.
However, for the conjugation of saccharides to proteins, including small saccharides, a protein that is not glycosylated is commonly used as a carrier.
Proteins that are glycosylated, such as KLH and ovalbumin, are not recommended as protein carriers for saccharides conjugations since their oligosaccharides may also induce the formation of antibodies when the resulting bioconjugates are used for the production of antibodies. The resulting non-desired antibodies present as impurities will interfere with the screening process, especially when the production of a specific monoclonal antibody is desired.
Proteins such as tetanus toxoids, edestin and serum albumin are recommended as carriers. Small saccharides are normally not immunogenic, therefore the conjugation of small saccharides to a carrier protein increases their immunogenicity. Hence, they are usually linked to a protein such that the structural integrity of the saccharide is maintained.
The specific chemical modification of a protein or proteins with sugar or saccharide moieties, as well as other molecules such as drugs, can enable the study of fundamentals in physiology and biochemistry. In addition, various types of bioconjugates may allow for the development and production of next-generation therapeutics or vaccines.