Sialidase (α2-3-6-8-9) is a broadly specific sialidase that cuts linear and branched non-reducing terminal sialic acid residues from glycoproteins, glycopeptides, and oligosaccharides. Sialidase (α2-3-6-8-9) can be used for in vitro and in vivo polysaccharide analysis and characterization as well as complete glycoprotein remodeling.