Figure 2.

Racemization of L-Ser to D-Ser at Ser 59 and Ser 62 in αA-crystallin as a function of age in normal and cataract lenses (symbols: □ Normal ♦ cataract). (a) Total D-Ser. The peak intensities of the D-Ser (59)/L-Ser (62), L-Ser (59)/D-Ser (62), and D-Ser (59)/ D-Ser (62) peaks were combined and the sum expressed as a function of the total ion abundance for the αA-crystallin peptide TVLDSGISEVR (normal; y = 0.443x ( 0.477, R² = 0.955, two-sided P 0.004). Mann–Whitney U test, two-sided P = 0.0286. (b) D-Ser 59. The peak intensities of the D-Ser (59)/L-Ser (62) and D-Ser (59)/D-Ser (62) peaks were combined and the sum expressed as a percentage of the total ion abundance for the αA-crystallin peptide, TVLDSGISEVR (normal; y = 0.153x (0.794, , R² = 0.994, two-sided P = 0.0002). Mann–Whitney U test, two-sided P = 0.0286. (c) D-Ser 62. The peak intensities of the L-Ser (59)/D-Ser (62) and D-Ser (59)/ D-Ser (62) peaks were combined and the sum expressed as a percentage of the total ion abundance for the αA-crystallin peptide, TVLDSGISEVR (normal; y = 0.4x 1.05, R² = 0.936, two-sided P = 0.007). Mann–Whitney U test, two-sided P = 0.0286. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]