Chemoenzymatic synthesis of the sialyl-α-(2→3′)-lactosamine trisaccharide with a 3-aminopropyl group as a spacer at the reducing end

The trisaccharide, 3-aminopropyl 5-acetamido-3,5-dideoxy- d- glycero-α- d- galacto-2-nonulopyranosylonic acid-(2→3)-β- d-galactopyranosyl-(1→4)-2-acetamido-2-deoxy-β- d-glucopyranoside has been synthesized chemoenzymatically for the first time. First, the acceptor, 3-aminopropyl β- d-galactopyranosyl-(1→4)-2-acetamido-2-deoxy-β- d-glucopyranoside was synthesized in a conventional chemical manner, and then it was coupled with CMP-sialic acid using α-(2→3)-( N)-sialyltransferase to afford the desired trisaccharide by an enzymatically stereocontrolled manner. Graphic