Chemo-enzymatic synthesis of tetra-, penta-, and hexasaccharide fragments of the capsular polysaccharide of Streptococcus pneumoniae type 14

The chemo-enzymatic synthesis is described of beta-D-Glcp-(1-->6)-[beta-D-Galp-(1-->4)]-beta-D-Glcp NAc-(1-->3)-beta-D-Galp-(1--> O(CH2)(6)NH2 (1), beta-D-Glcp-(1-->6)-[beta-D-Galp-(1-->4)-beta-D-Glcp NAc-(1-->3)-beta-D-Galp-(1-->4)-beta-D-Glcp-(1-->O(CH2)(6)NH2 (2), beta-D-Galp-(1 -->4)-beta-D-Glcp NAc-(1-->3)-beta-D-Galp-(1-->4)-beta-D-Glcp-(1-->O(CH2)(6)NH2 (3), and beta-D-Galp-(1-->4)-beta-D-Glcp NAc-(1--> 3)-beta-D-Galp-(1-->4)-beta-D-Glcp-(1-->6)-[beta-D-Galp-(1-->4)-beta-D-Glcp NAc-(1-->O(CH2)(6)NH2 (4), representing fragments of the repeating unit of the Streptococcuspneumoniae serotype 14 capsular polysaccharide. Linear intermediate oligosaccharides 5-8 were synthesized via chemical synthesis, followed by enzymatic galactosylation using bovine milk beta-1,4-galactosyltransferase as a catalyst. The title oligosaccharides form suitable compounds for conjugation with carrier proteins, to be tested as potential vaccines in animal models. (C) 2003 Elsevier Ltd. All rights reserved.