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. 2018 Oct 9;308(8):1113–1120. doi: 10.1016/j.ijmm.2018.10.001

Fig. 2.

Fig. 2

nanoESI mass spectra of chemically released sialic acids from BSM (A), and of sialic acids obtained by chemical release upon pretreatment of BSM with NanS-His (B) and NanS-p1-His (C). (A) The overview mass spectrum of BSM-derived sialic acids indicates the presence of Neu5Ac, Neu5Gc, Neu5Ac(OAc), Neu5Gc(OAc), Neu5,9(OAc)2, Neu5Ac(OAc)3 and Neu5Gc(OAc)3 in the O-glycans of BSM. (B) Ions corresponding to Neu5Ac, Neu5Gc, Neu5Ac(OAc), Neu5Gc(OAc), Neu5Ac(OAc)2 and Neu5Gc(OAc)2 were detected in the spectrum BSM-derived sialic acids after treatment with NanS-His. (C) The spectrum obtained from BSM-derived sialic acids after treatment with NanS-p1-His gives rise to ions corresponding to Neu5Ac, Neu5Gc, Neu5Ac(OAc), Neu5Gc(OAc) and Neu5Ac(OAc)2. Ac, Neu5Ac; Ac(OAc), Neu5Ac(OAc); Ac(OAc)2, Neu5Ac(OAc)2; Ac(OAc)3, Neu5Ac(OAc)3. Gc, Neu5Gc; Gc(OAc), Neu5Gc(OAc); Gc(OAc)2, Neu5Gc(OAc)2; Gc(OAc)3, Neu5Gc(OAc)3. The numbered ions in the mass spectra depicted in panel A, B, and C, are listed in Table 2A–C, respectively.