正常及老年性白内障晶状体中半胱氨酸和蛋氨酸的选择性氧化
Selective oxidation of cysteine and methionine in normal and senile cataractous lenses.
作者信息
Garner M H, Spector A
出版信息
Proc Natl Acad Sci U S A. 1980 Mar;77(3):1274-7. doi: 10.1073/pnas.77.3.1274.
The oxidation state of methionine and cysteine in normal and cataractous lenses is reported. In young lenses no oxidation was detected in any protein fraction examined. Only the intrinsic membrane fraction and membrane-related components showed evidence of oxidation in old (60-65 years of age) normal lenses. However, in a similar age group, with the development of cataract, progressive, dramatic changes were observed. With severe cataracts, 60% or more of the methionine in membrane-associated components was found in the methionine sulfoxide form, and methionine sulfone was observed in one case. Most of the cysteine was found oxidized to either the disulfide form or putative cysteic acid. Mixed disulfides with glutathione were observed. Oxidative changes in soluble components as illustrated by alpha-crystallin occurred more gradually. The data clearly support the viewpoint that extensive oxidation of lens proteins occurs with cataract and that it begins at the lens fiber membrane.
报道了正常晶状体和白内障晶状体中甲硫氨酸和半胱氨酸的氧化状态。在年轻晶状体中，在所检测的任何蛋白质组分中均未检测到氧化。在老年（60 - 65岁）正常晶状体中，只有内在膜组分和与膜相关的成分显示出氧化迹象。然而，在相似年龄组中，随着白内障的发展，观察到了渐进性的显著变化。在严重白内障中，膜相关成分中60%或更多的甲硫氨酸以甲硫氨酸亚砜形式存在，并且在一个病例中观察到了甲硫氨酸砜。大部分半胱氨酸被发现氧化为二硫键形式或假定的半胱氨酸。观察到了与谷胱甘肽形成的混合二硫键。如α - 晶状体蛋白所示，可溶性成分中的氧化变化更为缓慢。数据清楚地支持了这样的观点，即晶状体蛋白的广泛氧化随着白内障的发生而出现，并且始于晶状体纤维膜。
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