Enzymic synthesis of the trisaccharide core region of the carbohydrate chain of N-glycoprotein.

Transmannosylation from mannotriose (Man beta 1-4Man beta 1-4Man) to the 4-position at the nonreducing end N-acetylglucosaminyl residue of N,N'-diacetylchitobiose was regioselectively induced through the use of beta-D-mannanase from Aspergillus niger. The enzyme formed the trisaccharide Man beta 1-4GlcNAc beta 1-4GlcNAc (3.7% of the enzyme-catalysed net decrease of N,N'-diacetylchitobiose) from mannotriose as a donor and N,N'-diacetylchitobiose as an acceptor. Mannobiose (Man beta 1-4Man) was also shown to be useful as a donor substrate for the desired trisaccharide synthesis.