Α-N-Acetylneuraminyl-2,3-b-galactosyl-1,3-N-acetyl-galactosaminide 6-α-sialyltransferase explained

α-N-Acetylneuraminyl-2,3-b-galactosyl-1,3-N-acetyl-galactosaminide 6-α-sialyltransferase
Ec Number:	2.4.99.7
Cas Number:	129924-24-9

α-N-Acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetylgalactosaminide 6-α-sialyltransferase (sialyltransferase, cytidine monophosphoacetylneuraminate-(alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3)-N-acetylgalactosaminide-alpha-2,6-sialyltransferase, alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide alpha-2,6-sialyltransferase, SIAT7, ST6GALNAC, (alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3)-N-acetyl-galactosaminide 6-alpha-sialyltransferase, CMP-N-acetylneuraminate:(alpha-N-acetylneuraminyl-2,3-beta-D-galactosyl-1,3)-N-acetyl-D-galactosaminide alpha-2,6-N-acetylneuraminyl-transferase) is an enzyme with systematic name CMP-N-acetylneuraminate:N-acetyl-alpha-neuraminyl-(2->3)-beta-D-galactosyl-(1->3)- N-acetyl-D-galactosaminide galactosamine-6-alpha-N-acetylneuraminyltransferase.^[1] This enzyme catalyses the following chemical reaction

CMP-N-acetylneuraminate + N-acetyl-alpha-neuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-D-galactosaminyl-R

\rightleftharpoons

CMP + N-acetyl-alpha-neuraminyl-(2->3)-beta-D-galactosyl-(1->3)-[N-acetyl-alpha-neuraminyl-(2->6)]-N-acetyl-D-galactosaminyl-R

This enzyme attaches N-acetylneuraminic acid in alpha-2,6-linkage to N-acetyl-galactosamine only when present in the structure, where R may be protein or p-nitrophenol.

Notes and References

Bergh ML, Hooghwinkel GJ, van den Eijnden DH . Biosynthesis of the O-glycosidically linked oligosaccharide chains of fetuin. Indications for an alpha-N-acetylgalactosaminide alpha 2 leads to 6 sialyltransferase with a narrow acceptor specificity in fetal calf liver . The Journal of Biological Chemistry . 258 . 12 . 7430–6 . June 1983 . 6190802 .