What is the ideal conjugation density during bioconjugation reactions?
Or, what density of the conjugated residue should be the desirable one?
To create optimal bioconjugates for immunization purposes, usually, the targeted, or desired conjugation density is approximately twenty (20) to thirty (30) ligand residues per carrier molecule, especially if conjugated to a protein.
However, realistically, the experimental conjugation ratio may be in the order of 4 to 10 residues per protein molecule. In general, this conjugation ratio is sufficient to induce an effective immune response.
What is an immune response?
Many naturally occurring and synthetic biomolecules are immunogens that elicit an immune response without the need for conjugation. However, to elicit an immune response, a molecule must contain an antigenic determinant or epitope. This epitope must be of sufficient size to initiate lymphocyte activation necessary to make antibodies. In general small molecules are not good immunogens. On the other hand, when small molecules, such as sugars, oligonucleotides, or peptides, are conjugated or attached to macromolecules, also called carrier molecules, they can become immunogenic.
In immunology, small molecules or compounds are also called haptens.