(a) Extracted ion chromatograph showing m/z corresponding to Acetyl-Neu5Gc (Neu5Gc,Ac) and m/z of the same glycopeptides containing Neu5Gc. Examples of two individual glycopeptides are shown. (b) Representative MS/MS fragmentation of glycopeptide N1E2S1L1Y1T1A2I1K1 demonstrating presence of Acetyl-Neu5Gc (Neu5Gc,Ac). (c) For Fab glycans, the exact amino acid position and sequence are unknown, and shown are potential amino acid compositions given the observed mass size. Experiment was performed in triplicate with representative (a, b) and combined (c) data shown .