Native Electron Capture Dissociation for the Structural Characterization of Noncovalent Interactions in Native Cytochrome c

Selectively cleaved: Under appropriate experimental conditions, electrospray ionization mass spectrometry produces fragment ions that directly indicate noncovalent protein–heme interaction sites in native Cytochrome c (see picture). The proposed mechanism involves asymmetric charge partitioning in gaseous protein dimer ions, which causes electron transfer and subsequent backbone‐cleavage.