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

[graphics] beta-D-Galp-(1 -> 9)-D-KDN, a disaccharide component of the cell wall of Streptomyces sp. MB-8, was synthesized from beta-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 alpha 2,3- and alpha 2,6-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 alpha 2,6-sialyltransferase.