AGE & CATARACT RELATED CHANGES IN LENS PROTEIN STRUCTURE

在老化和白内障形成的过程中，晶状体透明度的丧失 与结构晶状体蛋白(晶状体蛋白)和 光散射。这些翻译后的变化已经在 人和牛的老化和白内障晶状体的蛋白质。他们 包括脱酰胺化、色氨酸氧化、蛋氨酸氧化 多肽链的选择性降解、二硫键 (蛋白质-蛋白质或混合二硫键)和非酶糖基化。 然而，目前还不知道这些修饰是否会诱导蛋白质 构象变化和在蛋白质聚集之前和 不能溶解。在这项提议中，物理化学测量(UV-Vis 吸收、圆二色、荧光和激光散射) 将被用来观察(1)蛋白质构象(包括 芳香族氨基化合物的二级和三级结构、微环境 酸和巯基)的变化是翻译后的结果 修改，如果他们这样做了(2)是否构象改变了晶状体 老化和白内障晶状体中的蛋白质会产生更大的光散射和 (3)这些蛋白质是否变得更容易受到外源压力的影响 (如紫外线照射和过氧化氢)，(4)在 蛋白质构象促进了蛋白质聚集和 不溶解，最后(5)磷酸果糖激酶 也经历类似于的构象和翻译后的变化 晶体蛋白。 这些诱导的晶状体蛋白质构象变化的意义是 它可能会增加通过减少的粒子的光散射 移动性，或通过增加蛋白质聚集和不溶解。 这项建议的长期目标是将 观察到的光散射变化的构象变化 蛋白质溶液和完整的晶状体在体外。

In the course of aging and cataract formation, loss of lens transparency is associated with aggregation of structural lens proteins (crystallins) and light scattering. These post-translational changes have been observed in both human and bovine proteins of aging and cataractous lenses. They include deamidation, oxidation of tryptophan, oxidation of methionine, selective degradation of polypeptide chains, disulfide bonding (protein-protein, or mixed disulfide) and non-enzymatic glycosylation. However, it is not known whether these modifications induce protein conformational changes and precede protein aggregation and insolubilization. In this proposal, physicochemical measurements (UV-VIS absorption, circular dichroism, fluorescence and laser light scattering) will be employed, to observe (1) whether protein conformations (including secondary and tertiary structures, microenvironments of aromatic amino acids and sulfhydryl groups) have changes as a result of post-translational modifications, and if they do (2) whether conformationally altered lens proteins from aging and cataract lenses give greater light scattering and (3) whether these proteins become more vulnerable to exogeneous stresses (such as UV irradiation and hydrogen peroxide), (4) whether the change in protein conformation has facilitated protein aggregation and insolubilization, and finally (5) whether the enzyme phosphofructokinase also undergoes conformational and postranslational changes similar to crystallins. The significance of these induced changes in lens protein conformation is that it may increase light scattering either through a decreased particle mobility, or through increased protein aggregation and insolubilization. The long-term objective of this proposal is to correlate induced conformational changes to changes in light scattering observed both in protein solutions and intact lenses in vitro.