Fig. 1. 193 nm UVPD mass spectra of the 9+ charge state of the (a) holo and (b) apo form of myoglobin. Panels to the right are expanded regions (m/z 2175 to 2350) with several ions labelled to illustrate the mass shift (+615.1695 Da) affiliated with retention of the heme group. Δ indicates the inclusion of heme in the fragment ions. The 50× amplification applies to both spectra.
