Figure 1.

Positive nanoESI mass spectra of hERα LBD acquired under different conditions. (A) hERα LBD in 50 mM NH₄OAc, pH 6. (B) hERα LBD in 50 mM NH₄OAc, pH 7.4. The broad homodimer peak under B indicates that more water/salt molecules are trapped in the folded structure. The M 13+ charge state expansion for pH 6 shows the post-translational modifications: (•) His₆-tag gluconolyation, (⋄) His₆-tag phosphogluconoylation.