Aldolase-catalyzed synthesis of β-D-Galp-(1→9)-D-KDN: A novel acceptor for sialyltransferases

β-D-Galp-(1→9)-D-KDN, a disaccharide component of the cell wall of Streptomyces sp. MB-8, was synthesized from β-D-Galp-(1→6)-D-Manp and pyruvate using a sialic acid aldolase. The obtained KDN-containing compound was a novel acceptor for bacterial sialyltransferases. Unusual α2,3- and α2,6-linked sialyltrisaccharides and a tetrasaccharide were synthesized using a one-pot two-enzyme system containing a Neisseria meningitidis CMP-sialic acid synthetase and a Pasteurella multocida sialyltransferase or a Photobacterium damsela α2,6-sialyltransferase.