Mass spectrometry analysis of C3 glycation in changing glucose. (A) A cumulative peptide map of the fifteen C3 samples analyzed by ESI-LC-MS/MS showing 88% coverage. Matched peptides are in bold and glycated residues are underlined. (B) A representative mass spectra of the C3 peptide containing K241/K242 showing glycation and biotinylation. (C) A space filling model of C3 showing the positions of glycated lysine residues in color.