(a N acetylneuraminyl 2,3 b galactosyl 1,3) N acetyl galactosaminide 6 a sialyltransferase

Alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetylgalactosaminide 6-alpha-sialyltransferase (EC 2.4.99.7, 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. 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 ⇌ 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.