   2.4.1.102 | UDP-N-acetyl-alpha-D-glucosamine + O3-[beta-D-galactosyl-(1->3)-N-acetyl-alpha-D-galactosaminyl]-L-seryl/threonyl-[protein] = UDP + O3-{beta-D-galactosyl-(1->3)-[N-acetyl-beta-D-glucosaminyl-(1->6)]-N-acetyl-alpha-D-galactosaminyl}-L-seryl/threonyl-[protein] |
C2GnT operates through an inverting mechanism following a SN2-like reaction in which the enzyme provides a catalytic base that activates the nucleophile (in C2GnT, this is the C6 hydroxyl group from a GalNAc residue) to displace the uridine 5'-diphosphate (UDP) leaving group from the UDP-GlcNAc donor in a concerted process. It is assumed that C2GnT follows the ordered bi-bi catalytic mechanism with the UDP-GlcNAc bindings first, followed by the disaccharide acceptor binding over the nucleotide sugar. Reaction mechanism, quantum mechanical/molecular modeling, overview |
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