Purification and characterization of a rabbit liver alpha 1 goes to 3 mannoside beta 1 goes to 2 N-acetylglucosaminyltransferase.

An alpha 1 goes to 3 mannoside beta 1 goes to 2 N-acetylglucosaminyltransferase has been purified 7000-fold in 36% yield from a Triton X-100 extract of rabbit liver acetone powder by affinity chromatography on UDP-hexanolamine agarose. Sodium dodecyl sulfate gel electrophoresis of the purified enzyme revealed two major bands with molecular weights of 58,000 and 46,000. Examination of the acceptor substrate specificity with pure oligomannosides revealed that the best acceptor had the following structure, (Formula: see text) and gave a single product in which N-acetylglucosamine was present in the sequence GlcNAc beta 1 goes to 2Man alpha 1 goes to 3Man beta 1 goes to 4 GlcNAc. Other terminal mannose residues in the best acceptor as well as that linked alpha 1 goes to 6 in the following oligosaccharide, (Formula: see text) were not acceptors. This specificity is in accord with the role of the transferase in the processing of mannose-containing oligosaccharides during glycoprotein biosynthesis.