N-acetyl-β-d-glucosaminyltransferases related to the synthesis of mucin-type glycoproteins in human ovarian tissue

The presence of N-acetyl-β-d-glucosaminyltransferases in microsome preparations from human ovarian tissues was investigated with UDP-GlcNAc and several synthetic oligosaccharides as acceptors. The products were identified by paper chromatography and the linkage of the 2-acetamido-2-deoxy-β-d-glucopyranosyl group incorporated into oligosaccharides was determined by exoglycosidase digestions, ¹H-n.m.r. spectroscopy, and methylation analysis. These results showed that ovarian microsome preparations contain both β-(1→3)- and β-(1→6)-N-acetyl-d-glucosaminyltransferase activities which might be involved in the synthesis of mucin-type glycoproteins. Substrate competition tests suggests that both UDP-GlcNAc:-Bn glycoside of β-d-GlcpNAc-(1→6)-α-d-GalpNAc [GlcNAc to GalNAc] and -Bn glycoside of β-d-Galp-(1→3)-[β-d-GlcNAc-(1→6)]-α-d-GalpNAc [GlcNAc to Gal] β-(1→3)-N-acetyl-d-glucosaminyltransferase activities reside in a single enzyme species.