Chemoenzymatic synthesis of deca and dodecasaccharide N-glycans of the 'bisecting' type

The synthesis of N-glycans carrying the 'bisecting' GlcNAc modification is difficult due to steric hindrance at the central beta-mannoside. A facile i ntroduction of a 'bisecting' GlcNAc residue was accomplished by using an ex cess of a glucosaminyl fluoride. After deprotection of the resulting octasa ccharide a 6-amino-hexanoyl spacer was attached. Enzymatic elongation of th e carbohydrate chains using three different glycosyltransferases gave full length 'bisecting' N-glycans of the complex type terminating with galactose , alpha-2,6 or alpha-2,3 linked sialic acid. (C) 2000 Elsevier Science Ltd. All rights reserved.