Figure 2.
The mass spectra observed for (A) ubiquitin (8,566 Da), (B) cytochrome c (12,359 Da), and (C) myoglobin (apo 16,951 Da; holo 17,567 Da) electrosprayed from both acidic organic (pH ~3, red traces) and aqueous buffered (pH ~6.6, blue traces) solution conditions. For myoglobin, the charge states labeled “holo” correspond to ions which retain the heme group (616 Da). Note that each mass spectrum represents two overlaid traces, each of which is normalized to the maximum ion abundance (y-axis).
