KDN is an abbreviated name of 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid, and belongs to sialic acid members like N-acetylneuraminic acid (Neu5Ac), and N-glycolylneuraminic acid (Neu5Gc). The aminoacyl group at C5 position of Neu5Ac is replaced by a hydroxyl group in KDN. Like Neu5Ac, KDN exists in various glycoconjugates including glycosphingolipids in vertebrates and gram-negative bacteria. Because of its unique properties, some methods are specifically applicable to KDN residue, although most detection methods for Neu5Ac are also applicable. In this chapter, methods for identification of KDN residues in glycosphingolipids are described, focusing on two methods that are often used, i.e., the fluorescent HPLC analysis and the TLC immunostaining with the antibodies specific to α2,3- and α2,8-KDN residues.
Keywords: Anti-KDN antibody; Deaminoneuraminic acid; Fluorometric HPLC analysis; KDN; KDN-ganglioside; Orcinol sulfuric acid method; Resorcinol method; Sialic acid; TLC immunostaining; Thiobarbituric acid method.