In our previous study (Y. Kimura
et al.,
Biosci. Biotechnol. Biochem.,
69, 137–144 (2005)), we found that plant complex type
N-glycans harboring Lewis a epitope are linked to the mountain cedar pollen allergen Jun a 1. Jun a 1 is a glycoprotein highly homologous with Japanese cedar pollen glycoallergen, Cry j 1. Although it has been found that some plant complex type
N-glycans are linked to Cry j 1, the occurrence of Lewis a epitope in the
N-glycan moiety has not been proved yet. Hence, we reinvestigated the glycoform of the pollen allergen to find whether the Lewis a epitope(s) occur in the
N-glycan moiety of Cry j 1. From the cedar pollen glycoallergen, the
N-glycans were liberated by hydrazinolysis and the resulting sugar chains were
N-acetylated and then coupled with 2-aminopyridine. Three pyridylaminated sugar chains were purified by reversed-phase HPLC and size-fractionation HPLC. The structures were analyzed by a combination of exo- and endo-glycosidase digestions, sugar chain mapping, and electrospray ionization mass spectrometry (ESI-MS). Structural analysis clearly indicated that Lewis a epitope (Galβ1-3(Fucα1-4)GlcNAcβ1-), instead of the Galβ1-4(Fucα1-6)GlcNAc, occurs in the
N-glycans of Cry j 1.
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