Fig. 3.

Basic residues reduce TMAO-mediated charge reduction. (a) Structures of wild-type and citrullinated LL-37. (b) Mass spectra of unmodified LL-37 (top) and with its five arginine residues neutralized by citrullination (bottom) show identical charge state distributions in the absence of collisional activation. (c) At a cone voltage of 300 V, citrullinated LL-37 exhibits greater charge reduction and reduced ion intensity than the unmodified peptide