ASCORBIC ACID GLYCATION AND SENILE CATARACT FORMATION

老年性白内障形成机制研究的首要目标 是发现可以抑制或至少延缓 白内障形成的过程。 如果这种病理可以推迟， 仅用10年，这将消除大部分白内障手术， 每年执行。 对老年人晶状体的分析显示， 蛋白质的聚集和交联，这被认为是 是白内障形成的基础 这些过程的化学过程， 然而，在很大程度上仍然未知。 我们一直在研究抗坏血酸对透镜蛋白的修饰 酸糖化，并发现了大量的相似之处， 体外糖化蛋白和老年人分离蛋白 眼镜. 晚期糖基化终产物的形成可能是 导致透镜变黄或变暗， 活性氧和蛋白质交联的形成。 这 工作受到了阻碍，因为人们对这两种情况知之甚少， 抗坏血酸糖化化学或抗坏血酸的结构 晚期糖基化终产物和一般的交联。工作中 在这里提出，我们将通过各种方法测量透镜蛋白的糖化。 抗坏血酸分解产物在“生理”条件下， 以测定每种化合物在糖化和交联中的活性。 将制备特定氨基酸对之间的交联，并将它们的 测量稳定性并与存在的交联的稳定性进行比较 在来自老化人透镜的水不溶性部分中。 化学性质 几个抗坏血酸衍生的交联将确定使用一个新的 用模型肽分离方法。 最后， 抗坏血酸糖基化产生的敏化剂将与 老化的人的透镜中产生的特定活性氧。

The primary goal of research on the mechanism of senile cataract formation is to discover treatments which can inhibit, or at least delay, the progression of cataract formation. If this pathology could be delayed by only 10 years, this would eliminate most of the cataract operations performed each year. Analysis of aged human lenses show increased aggregation and crosslinking of proteins, which are thought to be fundamental in cataract formation. The chemistry of these processes, however, remains largely unknown. We have been investigating the modification of lens proteins by ascorbic acid glycation, and have discovered a great number of similarities between in vitro glycated proteins and the proteins isolated from aged human lenses. The formation of advanced glycation endproducts may be responsible for the yellowing or brunescence of the lens, the generation of active oxygen species and the formation of protein crosslinks. This work has been hampered because so little is known about either the chemistry of ascorbic acid glycation in particular or the structure of advanced glycation endproducts and crosslinks in general. In the work proposed here we will measure the glycation of lens proteins by various ascorbic acid breakdown products under "physiological" conditions in order to determine the activity of each compound in glycation and crosslinking. Crosslinks between specific amino acid pairs will be prepared and their stability measured and compared to the stability of the crosslinks present in the water-insoluble fraction from aged human lens. The chemical nature of several ascorbate-derived crosslinks will be determined using a new isolation method with a model peptide. Finally, the nature of the sensitizers produced by ascorbate glycation will be compared to those in aged human lens for the specific active oxygen species produced.