Figure 1. The numbers of tandem mass (MS/MS) spectra are shown for peptides of each guinea pig lens water-soluble nuclear crystallin. A shows total counts for 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. Results for γN-crystallin are not shown because of a low number of detected total peptides (<50 counts). The counts in A correspond to a soluble protein sample of 0.4 mg. Seven crystallins (βA1/A3, βA4, βB1, βB2, βB3, γC, and γS) showed an O₂-induced decrease in counts for peptides containing a cysteine residue, while 5 crystallins (αA, βA2, γA, γB and ζ) showed an increase (A). All the crystallins except αA and βA4 showed an O₂-induced increase in PSSG level (B). βB2-crystallin exhibited the highest levels of control as well as O₂-induced PSSG. In C, all the crystallins except αA and βB3 showed an O₂-induced increase in PSSC level. γC-crystallin exhibited the highest levels of control as well as O₂-induced PSSC.