Scheme 1. Site-directed glycosylation of GLP-1 analogues with homogeneous biantennary complex-type N-glycan. The glycosylation site was introduced into GLP-1 by chemical synthesis. The peptides were initially glucosylated by ApNGTQ469A and then modified by EndoCCN180H with asialyl or sialyl complex-type N-glycan oxazoline (CT-oxa or SCT-oxa) as donor.
