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. Author manuscript; available in PMC: 2012 May 19.
Published in final edited form as: J Am Chem Soc. 2010 Nov 19;132(49):17411–17425. doi: 10.1021/ja9067035

Figure 7. Sodium chloride increases the rate of H/D exchange in both acetylated and unmodified BCA II.

Figure 7

A) Mass spectra of unmodified BCA II and acetylated BCA II (e.g., rungs Ac(13)-Ac(18)) after 80 min in D2O, 10 mM PO43−, pD 7.4, 0–1 M NaCl. The mass of each BCA II species increases with the concentration of NaCl (indicating an increase in the incorporation of deuterium). B) Plot showing the number of unexchanged hydrogens in unmodified and acetylated BCA II after 80 min in D2O, pD 7.4, 0–1 M NaCl. The number of unexchanged hydrogens in each protein decreases with increasing sodium chloride. Unmodified BCA II in 0 M NaCl and acetylated BCA II in 1 M NaCl have a similar number of unexchanged hydrogens after 80 min in D2O (note: the rungs corresponding to Ac(13) and Ac(18) are omitted from the bar graph because these rungs are low in intensity and did not yield precise values of mass).