ABSTRACT
OBJECTIVE To analyze the composition and function of N-glycoproteins in human plasma exosomes. METHODS Exosomes from human plasma were extracted by ultracentrifugation. The proteins from plasma exosomes were released by ultrasound and the obtained proteins were enzymatically degraded by trypsin to peptides. The N-glycopeptides in the mixture of the digested peptides was enriched by the hydrazide resin. The enriched N-glycoproteins were identified by mass spectrometry and subjected to gene ontology (GO) annotation analysis. RESULTS The plasma exosomes isolated by ultracentrifugation had a typical cup-shaped structure and the particle sizes were approximately 100 nm. Totally, 252 N-glycosylation sites corresponding to 131 N-glycoproteins were enriched and identified from exosomes of 1 mL human plasma digestion, which participated in many important biological processes, such as serine-type endopeptidase activity, serine-type endopeptidedase inhibitor acitivity and calcium ion binding. Sixty-seven of the N-glycoproteins had close relations with the occurrence of diseases. CONCLUSION Totally, 131 N-glycoproteins were identified in the research from the plasma exosome protein. These N-glycoproteins precipitate in many important biological processes and have close correlations with the occurrence and progression of various diseases.