Frontispiece: Construction of a High-Mannose-Type Glycan Library by a Renewed Top-Down Chemo-Enzymatic Approach.

A High ‐ Mannose ‐ Type Glycan Library The biological roles of protein glycosylation are well recognized. The addition of asparagine ‐ linked glycan chains is particularly important and the critical roles of high ‐ mannose ‐ type oligosaccharides in various aspects of glycoprotein quality control have attracted much attention in recent years. In their Full Paper on page 3224 ff., Y. Ito et al. report a chemo ‐ enzymatic strategy for the construction of a high ‐ mannose ‐ type glycan library by systematic chemo ‐ enzymatic trimming of a single Man9 ‐ based precursor that overcomes the limitation associated with the use of Gal residue as a capping element. The synthetic route led to a fluorescently labeled tridecasaccharide as the common precursor and the preparation of a complete set of mono ‐ and non ‐ glucosylated high ‐ mannose ‐ type glycans. The power of the methodology was demonstrated by the interaction with human recombinant N ‐ acetylglucosaminyltransferase ‐ I toward M7 ‐ M3 glycans, clarifying the glycan specificity in the context of high ‐ mannose ‐ type glycans. [ABSTRACT FROM AUTHOR]