Fig. 6. The pH-switchable HMW protein tube formation is reversible. Peroxiredoxin proteins were buffer exchanged from 100 mM ammonium acetate, pH 4.0, back into 100 mM ammonium acetate, pH 8.0, prior to injection into the MS instrument. The spectra for cleaved protein (A) shows the majority of the species returned to single rings of an experimental mass of 267 346 ± 93 Da. A very small population of two stacked rings (around 9000 m/z) can also be detected. The spectra for His6-tagged protein (B) shows only a single population of single rings with an experimental MW of 305 164 ± 80 Da.
