N-linked sugar chain of 55-kDa royal jelly glycoprotein

An N-linked sugar chain from 55-kDa royal jelly glycoprotein (RJGP), which maintains the high viability of rat liver primary cultured cell and is a different molecular species from 350-kDa RJGP [Kimura et al., Biosci. Biotech. Biochem., 59, 507-509 (1995)], has been identified. The sugar chains were released by hydrazinolysis followed by N-acetylation and pyridylamination. The structural analysis of the pyridylaminated sugar chain was done by a combination of sequential exo-mannosidase digestions, MALDI-TOF MS, and 500 MHz 1H-NMR. For the carbohydrate moiety of 55-kDa RJGP, only one N-linked sugar chain has been detected. The structure has been found to be Man alpha 1-->2Man alpha 1-->6(Man alpha 1--> 2Man alpha 1-->3)Man alpha 1-->6(Man alpha 1-->2Man alpha 1-->2Man alpha 1-->3)Man beta 1-->4GlcNAc beta 1-->4GlcNAc, which is a non-processed high mannose type structure.