Analysis The Sialic Acid Glycoprotein N-glycan From Saliva Of Healthy Volunteers

As the first inherent barrier, saliva helps human to resist respiratory viral infecti-ons and in which salivary glycoprotein plays an important role. The sialic acid glycan receptors from the terminals of a-2-macroglobulin, mucin5B, and salivary glycoprotein340in saliva could neutralize and suppress the infection from influenza virus by bonding to influenza virus surface glycoproteins HA (Hemagglutinin). Influenza virus HA recognize the SA receptor from the surface of the host cells,further more, human influenza virus HA mainly recognize the end of the sialic acid a2-6(SAα2-6Gal) galactose linked glycan receptor whereas Avian influenza virus HA mainly show recognition to the end of the sialic acid a2-3(SAα2-3Gal) galactose linked glycan receptor. Previously, our laboratory have analyzed saliva from healthly volunteers in three different ages. The result showed that some sliavia glycoprotein glycans are relevant to age and sex. For example, the amount of glycan expressions on SA salivary glycoproteins increased significantly with the change of age, nevertheless, the amount of protein expression did not change strikingly. The result also found that the saliva of the healthly elders could provide more tenninal SAa2-6Gal and SAa2-3Gal glycan receptors to bind and neutralize influenza virus by recognizing human specific receptors on the surface of airway cells respiratory tract, making the healthy elders have a stronger ability to resist influenza.This experiment hope to study further about the specific structure of sialic acid glycan in saliva and to understand the difference of sialic acid glycan structures in different genders as well as different ages.This experiment uses lectin SNA/MAL-Ⅱ magnetic particles composite to separate the sialic acid glycoprotein from saliva of healthy volunteers. The saliva samples are grouped according to age and gender. Lectin SNA mainly recognizes glycans with terminal of SAa2-6Gal, while lectin MAL-II mainly recognizes glycans with the terminal of SAα2-3Gal. The sialic acid glycoproteins extracted by lectin SNA/MAL-Ⅱ were digested by PNGaseF and then obtained the sialic acid N-glycan afterwards. The glycan were identified by MADLI-TOF/TOF-MS after purification and desalination.The data analysis results are as follows:(1) The sialic acid glycan isolated by lectin SNA.43and27glycan structure were identified from elderly men and women. In these glycans,30and18were sialic acid glycan. 20and26glycan structure were identified from adult. In these glycans,13and21were sialic acid glycan.32and34glycan structure were identified from child, In these glycans,25and26were sialic acid glycan. Compare with adult and elder, the macromolecule glycan is less than adult and elder. Some glycan exist in three sample.(2) The sialic acid glycan isolated by lectin MAL-Ⅱ.37and33glycan structure were identified from elderly men and women. In these glycans,26and25were sialic acid glycan.24and28glycan structure were identified from adult. In these glycans,19and22were sialic acid glycan.17and20glycan structure were identified from child. In these glycans,16and17were sialic acid glycan. Elder have the most glycan and sialic glycan.Throughout the sugar chain spectra, N-glycan with sialic acid modification were mainly distributed in1300-3500Da. Macromolecules glycan were identified.Glycan type in elder is abundance. In the glycan isolated by MAL-Ⅱ, elder have more glycan number. This is may be why elder people have a stronger resistance to influenza viruses.Besides, the mass spectrometric data show that same age of different gender has different glycan.