Unveiling the N-Glycomic Diversity of Goat Lactoferrin during Lactation

Goat lactoferrin is an N-glycoprotein, and its glycan moieties are essential for its biological activity. However, the structures of these glycans, particularly the sialylated isomers with α-2,3- or α-2,6-linkages, remain poorly characterized. Utilizing online hydrophilic liquid chromatography-tandem mass spectrometry, our study characterized N-glycans in goat lactoferrin across different lactation stages, and the putative structures of the 86 N-glycans of goat lactoferrin were presented, including 53 previously undetected ones. The content and variety of N-glycans decreased from colostrum to mature milk, with transitional milk exhibiting the highest levels of neutral and high-mannose N-glycans. Colostrum was particularly rich in fucose- and sialylated N-glycans, especially those with α-2,6-linkages. Notably, the α-2,6-linked sialylated N-glycan H5N4F1A1-1 was 7.09-fold and 12.85-fold more abundant in colostrum compared to transitional and mature milk, respectively. These findings provide valuable insights into the structure of lactoferrin and could facilitate the development of functional goat milk products.