Figure 1

(a) Cation exchange (CEX) chromatogram of end of fermentation (EOF) product of mAb X. The acidic, main, basic (B1, B2, B3, B4) and far basic variant (B5) are marked. (b) Stacked overlay of a portion of tryptic peptide map UV profile of far basic variant (FBV, top panel) and main variant (MV, bottom panel) of mAb X. The extra signal (at RT = 57.39 min) in FBV profile is marked. (c) Comparison of MS signals observed around RT of 57–58 min in FBV (top panel) and MV (bottom panel). The m/z 906.45, z = 2 signal is observed in FBV and absent in MV.