Figure 5. The numbers of tandem mass (MS/MS) spectra are shown for the 2 -SH group-containing peptides of water-soluble nuclear βB2-crystallin.
A shows total counts for each of the 2 peptides containing an −SH group;
B shows peptides containing protein-bound glutathione (PSSG) expressed as per −SH peptide; and
C shows peptides containing protein-bound cysteine (PSSC) expressed as per −SH peptide. Open bars are counts from age-matched
controls and solid black bars are counts after 30 treatments of the animals with hyperbaric oxygen. There is a different vertical
scale for
A, compared to those for
B and
C, which are identical. The counts in panel
A correspond to a soluble protein sample of 0.4 mg.
A shows that peptides for each of the 2 cysteine residues showed a slight O
2-induced decrease in number of counts. The majority of control and O
2-induced PSSG was shown by residue C67 (
B). Note that this single residue of βB2 produced the highest levels of control and O
2-induced PSSG, compared to the other 11 crystallins (see
Figure 1B). Residue C67 produced relatively little control or O
2-induced PSSC (
C), compared to the amounts observed for PSSG (
B).