Probing asymmetric charge partitioning of protein oligomers during tandem mass spectrometry

摘要: Dissociation of gaseous protein complexes produced by native electrospray often induces an asymmetric partitioning charge between ejected subunits. We present a simple factor (ACPF) to quantify the magnitude asymmetry in this effect. When applied monomer ejection from cytochrome c dimer and β-amylase tetramer, we found that ~60-70% precursor ending up monomers corresponds ACPFs 1.38 2.51, respectively. Further, used site-specific fragmentation electron transfer dissociation (ETD) identify differences characterize domains secondary-structure dimer, monomers, obtained directly ionization (ESI). evidence structural changes monomer, but also had nearly identical set fragment ions ETD as ESI with same state. Surprisingly, APCF values for generated revealed fragments undergo at over twice observed monomer.