Figure 2. Mass spectra transformed to the mass scale of α-crystallins. The vertical and horizontal axes correspond to the relative protein abundance and m/z, respectively. The expected cleavage fragments and [measured mass values in MALDI-TOF spectra (Da)/theoretical value (Da)] are indicated. Spectra were acquired for each sample in which digestion by endoproteinase Asp-N was quenched at 0 min (not digested), 10 min, 30 min, 1 h, 3 h, and 24 h. A: Human αA-crystallin. B: Human αB-crystallin.