Figure 3.

Mass envelopes and corresponding deuterium incorporation plots for two fragments from the mass spectrum of β-lactamase in the presence (dotted line) or absence (solid line) of the aggregator rottlerin. The spectra have been expanded to show the isotopic distribution of the ions of interest: (A) the peptide containing residues 132−146 (monoisotopic m/z = 908.4, +2 charge state) and (B) the peptide containing residues 291−322 (monoisotopic m/z = 813.7, +4 charge state). For each peptide, the isotopic distributions are shown for (i) the undeuterated sample, (ii) the sample that was deuterated for 4 h in the absence of rottlerin, and (iii) the sample that was deuterated for 4 h in the presence of rottlerin.