SYNTHESIS OF CARBOHYDRATE AMINO-ACID CONJUGATES RELATED TO THE CAPSULAR ANTIGEN K54 FROM ESCHERICHIA-COLI O6-K54-H10 AND ARTIFICIAL ANTIGENS THEREFROM

The disaccharides alpha-L-Rhap-(1 --> 3)-beta-D-GlcpA and beta-D-GlcpA-(1 --> 3)-alpha-L-Rhap bearing amide-linked L-serine or L-threonine, which represent the repeating unit(s) of the capsular polysaccharide from E. coli O6:K54:H10, have been synthesised. O-tert-Butyl-protected amino acid tert-butyl esters were condensed with the corresponding biouronic acid as the 2-acrylamidoethyl or 2-azidoethyl glycosides. The azido function was replaced by the acrylamido group by catalytic hydrogenation followed by N-acryloylation. The tert-butyl groups were removed by treatment with trifluoroacetic acid to give the target monomers which were copolymerised with acrylamide to give neoglycoconjugates that are potentially useful for immunochemical studies.