Blondin J, Baragi V, Schwartz E, Sadowski J A, Taylor A
J Free Radic Biol Med. 1986;2(4):275-81. doi: 10.1016/s0748-5514(86)80010-1.
Large accumulations of postsynthetically oxidized proteins are observed in the aged and cataractous eye lens. Ascorbate has previously been used to delay photooxidative damage in vitro. The goals of this study were to confirm that dietary ascorbate can be used to enhance lens ascorbate levels and to determine if lenses with enhanced ascorbate can better withstand photooxidative stress in the form of ultraviolet (UV) light exposure. Guinea pigs were placed on high dietary ascorbate (HDA), 50 mg/day, and low dietary ascorbate (LDA), 2 mg/day, for 21 weeks. Lenses from HDA animals were found to contain 3.3 times more ascorbate than LDA animals. Prior to irradiation, SDS-PAGE protein profiles and exopeptidase activity in HDA and LDA lens soluble proteins were indistinguishable. However upon exposure to UV light, more protein damage (e.g., high-molecular-weight aggregates and enhanced loss of exopeptidase activity) was seen in lens preparations from LDA as compared to HDA animals. These results suggest that ascorbate protects lens components against cataract-like and age-related postsynthetic changes in vivo. As in previous tests on lens preparations, attenuated exopeptidase activity was observed before protein aggregation.
在老化和白内障晶状体中观察到大量合成后氧化的蛋白质堆积。抗坏血酸此前已被用于在体外延缓光氧化损伤。本研究的目的是确认膳食抗坏血酸可用于提高晶状体抗坏血酸水平，并确定抗坏血酸水平升高的晶状体是否能更好地抵御紫外线（UV）照射形式的光氧化应激。将豚鼠分别给予高膳食抗坏血酸（HDA，50毫克/天）和低膳食抗坏血酸（LDA，2毫克/天），持续21周。发现来自HDA组动物的晶状体所含抗坏血酸比LDA组动物多3.3倍。在辐照前，HDA和LDA晶状体可溶性蛋白的SDS-PAGE蛋白质谱和外肽酶活性没有差异。然而，在暴露于紫外线后，与HDA组动物相比，LDA组动物的晶状体制剂中出现了更多的蛋白质损伤（例如高分子量聚集体和外肽酶活性增强丧失）。这些结果表明，抗坏血酸可保护晶状体成分免受体内类似白内障和与年龄相关的合成后变化的影响。与之前对晶状体制剂的测试一样，在蛋白质聚集之前就观察到外肽酶活性减弱。
