Preparation of asparagine-linked monoglucosylated high-mannose-type oligosaccharide from egg yolk.

Monoglucosylated high-mannose-type glycan (Glc1Man9GlcNAc2: G1M9) is well-known as a key glycoform in the glycoprotein folding process, which is specifically recognized by lectin chaperones calnexin (CNX) and calreticulin (CRT) in the endoplasmic reticulum (ER). In this work, we developed an efficient method for the preparation of G1M9-Asn. The G1M9-Asn was obtained from the IgY-rich fraction derived from hen egg yolk by the digestion with pronase. The α-amino group of asparagine in G1M9-Asn was protected with the 9-fluorenylmethyloxycarbonyl (Fmoc) group and the labeled glycans were subsequently purified using high performance liquid chromatography (HPLC). This method will provide useful substrates for analysis of the glycoprotein folding cycle in the ER.