Figure 2

Deuterium incorporation vs. H/D exchange period for five representative peptides, along with HDX mass spectra for at three indicated incubation periods.
For each peptide exhibiting significant difference in HDX behavior between apo GroEL and GroEL-ATPγS (e.g., peptides 6-13, 238-253, 387-406 and 459-466), a clear bimodal isotopic distribution is observed. However, for peptide 117-127 which is unaffected by nucleotide binding, a single isotopic distribution is observed.