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 de-glycosylated 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.