Naturally Occurring Glycosidases in Milk from Native Cattle Breeds: Activity and Consequences on Free and Protein Bound-Glycans

Identification and comparison of N-glycome profiles from common dietary protein sources

The N-glycomes of bovine whey, egg white, pea, and soy protein isolates are described here. N-glycans from four protein isolates were analyzed by HILIC high performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry (HILIC-FLD-QTOF-MS/MS). In total, 33 N-glycans from bovine whey and egg white and 10 N-glycans from soy and pea glycoproteins were identified. The type of N-glycans per glycoprotein source were attributable to differences in biosynthetic glycosylation pathways. Animal glycoprotein sources favored a combination of complex and hybrid glycan configurations, while the plant proteins were dominated by oligomannosidic N-glycans. Bovine whey glycoprotein isolate contained the most diverse N-glycans by monosaccharide composition as well as structure, while plant sources such as pea and soy glycoprotein isolates contained an overlap of oligomannosidic N-glycans. The results suggest N-glycan structure and composition is dependent on the host organism which are driven by the differences in N-glycan biosynthetic pathways.

Site-specific glycoproteomic analysis of purified lactoferrin from human and animal milk

Lactoferrin is a highly glycosylated protein, which have important biological functions in the growth and development of neonates. However, the glycoforms and glycosylation sites differed between species. The aim of the study was to identify the glycosylation profile (including glycosites, glycan structures, and glycoforms) of purified lactoferrin from human and animal (cow, goat, sheep) milk by using site-specific glycoproteomics technique. In total, a number of 89 N-glycans were identified in human and animal milk lactoferrin. We identified three N-glycosites with 23 different compositions of N-glycans in cow lactoferrin (CLF), four distinctive N-glycosites with 34 dissimilar N-glycan compositions in goat lactoferrin (GLF), five N-glycosites with 57 different N-glycan compositions in sheep lactoferrin (SLF), while five unique N-glycosites with 50 different N-glycan compositions were ascertained in human lactoferrin (HLF). HLF had the most complex glycan, while animal lactoferrin had the most high-mannose glycoforms. The results of this study further our understanding of lactoferrin differences between human and animal milk, which can provide a perspective on the analysis of differences in functional characteristics.