The synthesis and evaluation of novel sialic acid analogues bound to matrices for the purification of sialic acid-recognising proteins.

A novel N-acetylneuraminic acid analogue, 2-S-(5'-aminopentyl) 5-acetamido-3,5-dideoxy-2-thio-D-glycero-alpha-D-galacto-2- nonulopyranosidonic acid, as well as the thiosialoside 2-S-(2'-aminoethyl) 5-acetamido-3,5-dideoxy-2-thio-D-glycero-alpha-D-galacto-2- nonulopyranosidonic acid, have been synthesised and successfully coupled to CNBr-activated Sepharose 4B through the terminal amino group. The resultant affinity resins have proved efficient in purifying a number of sialic acid-recognising proteins such as Vibrio cholerae sialidase, sialidase-L from leech, trans-sialidase from Trypanosoma cruzi, and sialyltransferases from rat liver, all in high yield.

Synthesis and evaluation of N-acetylneuraminic acid-based affinity matrices for the purification of sialic acid-recognizing proteins.

The synthesis of 2-S-(2-aminoethyl) 5-acetamido-3,5-dideoxy-2-thio-D-galacto-2-nonulopyranosidonic acid (1) has been successfully achieved from the precursors methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-2-S-acetyl-3,5-dideoxy-2-thio-D-glyce ro-alpha-D-galacto-2-nonulopyranosonate (2) and 2-bromo-N-(tert-butoxycarbonyl)-ethylamine (5). Compounds 1 and 2 were coupled, via amino and thioglycosidic linkages, respectively, to epoxy-activated Sepharose 6B. The resultant affinity adsorbents have proved efficient in purifying the sialic acid-recognizing enzyme Vibrio cholerae sialidase, in a one-step process with yields in the order of 60%.