Description
General description
Recombinant human Beta-galactoside alpha-2,6-sialyltransferase 1 (ST6Gal I) is expressed in human HEK 293 cells as a glycoprotein with a calculated molecular mass of 43.5 kDa (amino acids 27-406). The DTT-reduced protein migrates as a ~50 kDa polypeptide on SDS-PAGE due to glycosylation. This protein is manufactured in human cells, with no serum. The human cells expression system allows human-like glycosylation and folding, and often supports higher specific activity of the protein. The protein is produced with no artificial tags.
Biochem/physiol Actions
ST6Gal I catalyzes the transfer of CMP-N-acetylneuraminate (CMP-sialic acid, CMP-NANA) to the β-D-galactosyl-1,4-N-acetyl-D-glucosaminyl termini on glycoproteins. Sialic acids are distributed in a variety of glycolipids and glycoproteins.¹ The sialic acid that is added to a galactose (Gal) can be bound either to the hydroxyl attached to carbon-3 of Gal to form an α-2,3 glycosidic linkage, or to the hydroxyl group attached to carbon-6 to form an α-2,6 glycosidic linkage.¹ ST6Gal I generates a α-2,6 linkage of sialic acid on the non-reducing, terminal Galβ1 4GlcNAc residues of oligosaccharides and glycoconjugates.²
Terminal sialylation has been shown to decrease Fcγ receptor binding and increase anti-inflammatory activity,³ as well as antibody-dependent cellular cytotoxicity in different studies by reduced binding of sialylated antibody towards FcγRIIIa.⁴⁻⁵
This recombinant ST6Gal I product can be used to study the mode of action of the enzyme, as well as its potential inhibitors. It can also be used as a glycoengineering tool to modify glycoproteins in vitro.
CMP-N-acetylneuraminate (CMP-sialic acid, CMP-NANA) to the β-D-galactosyl-1,4-N-acetyl-D-glucosaminyl termini on glycoproteins.
Sialic acids are distributed in a variety of glycolipids and glycoproteins. The sialic acid that is added to a galactose (Gal) can be bound either to the hydroxyl attached to carbon-3 of Gal to form an α-2,3 glycosidic linkage, or to the hydroxyl group attached to carbon-6 to form an α-2,6 glycosidic linkage. ST6Gal I generates a α-2,6 linkage of sialic acid on the non-reducing, terminal Galβ1 4GlcNAc residues of oligosaccharides and glycoconjugates.
Terminal sialylation has been shown to decrease Fcγ receptor binding and increase anti-inflammatory activity, as well as antibody-dependent cellular cytotoxicity in different studies by reduced binding of sialylated antibody towards FcγRIIIa.
Other Notes
One unit is defined as the amount of enzyme required to transfer 1.0 nanomole of sialic acid from CMP-NANA to asialofetuin per minute at pH 6.0, 37oC.
