Fig. 5.

Quaternary structural characterization of N-αβα. (A) Native MS analysis of N-αβα prototype. Under nondissociative conditions, charge series corresponding to 10 and 30 N-αβα oligomers were unambiguously assigned in the MS spectrum (green and purple dots, respectively). The 30+ charge state that was selected for tandem MS analysis is shadowed in red. (B) Tandem MS of the N-αβα 30-mer oligomer releases a highly charged monomer (blue; at the lower m/z range) and a stripped 29-mer oligomer (red), confirming the oligomer stoichiometry. The spectra are magnified threefold above 7,000 and below 2,000 m/z.