Analysis of the N -Glycoforms and Immunoactivity of Chinese Yam ( Dioscorea opposita Thunb.) Glycoprotein 30CYGP.

The major protein in Chinese yam (Dioscorea opposita Thunb.) glycoprotein, 30CYGP, exhibits strong immunomodulatory activities. Research has identified the sequence and structure of 30CYGP; however, 30CYGP N-glycoform composition and immunoactivity remain unknown. We isolated and purified 30CYGP from Chinese yam and used that material to release the N-glycans contained within. The N-glycans were labeled with 1-phenyl-3-methyl-5-pyrazolone and analyzed via ESI-MS and online LC-MS. Additionally, the immunoactivities of 30CYGP and deglycosylated 30CYGP in the RAW264.7 cell line were investigated. Six 30CYGP N-glycans were observed in total, in which three were modified with xylose (XM: 40%) and three with xylose and fucose (XFM: 60%). Furthermore, de-glycosylated 30CYGP had significantly weaker immunoactivity than 30CYGP. This study demonstrated that novel N-glycoforms may enhance 30CYGP immunoactivity. Further research on the role of varied glycosylation patterns in immunoactivity is needed.