Highly concentrated crystalline family is correctly folded and packed to maintain transparency in lens. On the other hand, lens does not have turn over function. Therefore, spontaneous post-translational modifications, such as deamidation and isomerization are accumulated during a life. In this study, we focused on the distribution and contribution of deamidation and isomerization in lens crystalline. The distributions of each of modification were screened by conventional and non-conventional mass spectrometry. In order to predict the contribution of site-specific modification, each of target amino acid in crystalline was replaced by deamidated ones, or various other amino acid using site directed mutagenesis. Each of recombinant crystalline was expressed by E.coli. Those crystalline biophysics were compared with wild type crystalline. Those results showed the distributions of modification are diﬀerent depending on crystalline oligomer states or crystalline solubility in aged lens. The result suggested that the modifications in crystalline would induce abnormal subunit-subunit interaction, and reduce stability in aged lens. This implied one reason for senile cataract formation in aged lens via spontaneous post-translational modification in crystallines.
Lutein is indicated eﬀective on preventing age-related macular degeneration while epidemiological surveys on inhibiting cataracts did not reach the consensus. Confounding factors, such as individual diﬀerences and the changes in amount of daily intake, may interfere with the results. We investigated the changes in oxidative status after administering supplement which containing determined dose of antioxidants by measuring samples from patients with identical grades of cataracts in both eyes. By this method, the individual diﬀerences and the changes in daily intake can be controlled. Aqueous humor and the lenticular anterior capsule samples were collected during cataract surgery before six-week oral administration of Ocuvite+Lutein®, an antioxidant supplement, as pre-intake. Post-intake samples were collected with the same method during cataract surgery of the opposite eye after the supplementation. The superoxide scavenging activity increased while total hydroperoxides decreased in aqueous humor after the supplementation. In the lenticular anterior capsule, the expression of glucose-6-phosphate dehydorgenase, a rate-determining enzyme of the pentose phosphate cycle, and 18S rRNA, related to protein synthesis in ribosome, increased. On the other hand, the expression of Aquaporin 8, a diﬀusion facilitator of hydrogen peroxide, decreased. According to the results of this study, the lutein-containing supplement suppresses the oxidation in the lens, and the potential in preventing the onset and the progression of cataracts was suggested.