Investigation of the stability of thiosialosides toward hydrolysis by sialidases using NMR spectroscopy

H-1 NMR spectroscopy has been used to investigate whether the alpha(2-->6)- linked thiosialoside 3 and the alpha(2-->3)-linked thiosialoside 9 are hydr olyzed in the presence of Vibrio cholerae sialidase, Similarly, the hydroly sis of the O-ketosides Neu5Ac-2-O-alpha-(2-->3)-Gal beta Me (4) and the alp ha-(2-->6)-sialyllactoside 7, representing natural alpha(2-->3)- and alpha( 2-->6)-linked sialosides, respectively, was investigated. The results of th e H-1 NMR experiments clearly demonstrate that the thiosialosides are not h ydrolyzed by Vibrio cholerae sialidase, As expected, the O-sialosides are h ydrolyzed to give N-acetyl-alpha-D-neuraminic acid as the first product of substrate cleavage.