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. Author manuscript; available in PMC: 2016 Jun 1.
Published in final edited form as: Electrophoresis. 2015 Jun;36(11-12):1314–1329. doi: 10.1002/elps.201400528

Figure 3. Diagnostic digestion of pyridylamino-labelled paucimannosidic N-glycans with α 1,2/3-mannosidase.

Figure 3

The effects of α1,2/3-mannosidase on five different RP-HPLC (C18) fractions from either the PNGase F or PNGase A pools was monitored by MALDI-TOF MS: (A, B) spectra of the PNGase F C18 fraction of 5.9 g.u. (hence annotated as F 5.9 g.u.) before and after α1,2/3-mannosidase digestion, demonstrating the isomeric forms of Man2GlcNAc2 and Man6GlcNAc2; (C, D) spectra of the PNGase F C18 fraction of 9.8 g.u. before and after α1,2/3-mannosidase digestion, demonstrating the major isomeric form of Man2GlcNAc2Fuc1; (E,F) spectra of the PNGase F C18 fraction of 10.3 g.u. before and after α1,2/3-mannosidase digestion, demonstrating two isomeric forms of Man3GlcNAc3Fuc0-1; (G,H) spectra of the PNGase F C18 fraction of 17 g.u. before and after α1,2/3-mannosidase digestion, demonstrating a minor isomeric form of Man3GlcNAc3Fuc1; (I,J) spectra of the PNGase A C18 fraction of 7.0 g.u. before and after α1,2/3-mannosidase digestion, demonstrating the isomeric status of Man2GlcNAc2Fuc2 as well as co-eluting Man3,5GlcNAc2. Note that the α1,3-mannose attached to the core α1,6-mannose is resistant to this enzyme. Asterisks indicate non-glycan contaminants in some low-intensity fractions; glycans are annotated with the m/z values for the [M+H]+ ions, unless otherwise indicated.