Structure of pentasaccharide of glycopeptide from TIME-EA4, N-glycoprotein in silkworm diapause eggs

The TIME-EA4, from silkworm diapause eggs of pure strain C108, Bombyx mori, has glycosylated chain as tetrasaccharide (Man2GlcNAc2) attaching to the Asn(22) of T3 peptide from tryptic digests. On the other hand, from Showa silkworm strain we additionally observed a pentasaccharide (Man3GlcNAc2) on T3 at the same linkage site. The linkage pattern of the 5-sugar chain was studied through Smith degradation combined with LC–MS and MS/MS analyses. These advanced methods led us to conclude that the pentasaccharide was branching as Man 1 → 3(Man 1 → 6)Man 1 → 4GlcNAc 1 → 4GlcNAc.