FIGURE 4.

Example MS spectra of intra-molecular and intermolecular cross-links identified in monomeric and dimeric apoA-IV. a shows the mass spectra for the M3H⁺ ion resulting from the cross-link 182–193 × 228–234 in the monomeric (blue) and dimeric (green) samples indicating a clear intramolecular span in both. b shows the same for the M4H⁺ ion resulting from the cross-link 94–110 × 191–202 showing that the cross-link is intermolecular in the dimer sample but intramolecular in the monomeric sample.