Fig. 2.

TMAO-mediated charge reduction produces the same end charge state and arrival time distribution for native-like and denatured myoglobin. (a) Mass spectra of myoglobin in the presence of 100 mM TMAO in 1 M ammonium acetate, pH 7.5 (black trace) or 10% formic acid (red trace) produce apo- and holo-myoglobin. (b) Increasing the ion trap voltage to 200 V results in an average charge of 3+ for both apo- and holo-myoglobin. (c) The 3+ ions of apo-myoglobin (red) and holo-myoglobin (black) shown in (b) have similar arrival time distributions, and hence similar CCSs