Sialic Acids (a family of derivatives of neuraminic acid) are usually found as terminal structures of both N-linked and O-linked glycans.
Being located at the terminal position of glycans, sialic acids are a likely point of contact for many glycoprotein interactions. They are also important for the stability and 3D conformation of glycoproteins and are involved in many biological interactions:
• Sialyation of IgG reduces ADCC and increases anti-inflammatory activity
• Sialic acids increase the serum half-life of glycoproteins by preventing uptake by the liver’s asialoglycoprotein receptor
• NGNA(Neu5Gc), a glycan not found in humans, can illicit an immune response and lead to increased neutralization of biopharmaceuticals.
• Cell line choice can greatly influence the type of neuraminic acids present on a biopharmaceutical, for example a large portion of the sialic acids on mouse IgG are often NGNA.