Functional Neoglycopeptides: Synthesis and Characterization of a New Class of MUC1 Glycoprotein Models Having Core 2-Based O-Glycan and Complex-Type N-Glycan Chains

An efficient protocol for the construction of MUC1-related glycopeptide analogues having complex O-glycan and N-glycan chains was established by integrating chemical and enzymatic approaches on the functional polymer platforms. We demonstrated the feasibility of sortase A-mediated ligation between two glycopeptide segments by tagging with signal peptides, LPKTGLR and GG, at each C- or N-terminal position. Structural analysis of the macromolecular N,O-glycopeptides was performed by means of ESI-TOFMS (MS/MS) equipped with an electron-captured dissociation device. Immunological assay using MUC1 glycopeptides synthesized in this study revealed that N-glycosylation near the antigenic O-glycosylated PDTR motif did not disturb the interaction between the anti-MUC1 monoclonal antibody and this crucial O-glycopeptide moiety. NMR study indicated that the N-terminal immunodominant region [Ala-Pro-Asp-Thr(O-glycan)-Arg] forms an inverse γ-turn-like structure, while the C-terminal region composed of N-glycopeptide an...