Sialyltransferases belongs to the glycosyltransferases family with the capability of catalyzing the transfer of N-acetylneuraminic acid residues. It is a multifunctional enzyme with α-2,3-sialyltransferase activity, α-2,6-sialyltransferase activity, sialidase activity, and trans-sialidase activity. It has a molar mass of 46.4 kDa, with pI, pH being 5.94 and 7.5-8.5 respectively.
Sialyltransferase catalyzes the transfer of Neu5Ac from CMP-Neu5Ac as a donor substrate to the β-D-galactosyl-1,4-N-acetyl-D-glucosaminyl termini of acceptor molecules including glycoproteins, glycolipids, and oligosaccharides.