糖基化对α-晶状体蛋白的修饰和分子伴侣活性的降低  

Modification of α-crystallin and reduction of molecular chaperone activity by glycation

作　　者：严宏[1] 惠延年[1] 范建国[2] 张延凤[3] 武丽华[3] 张晓楠[3] 

机构地区：[1]第四军医大学西京医院眼科研究所,710032 [2]第四军医大学分析检测中心 [3]西安北京军区总医院眼科,100700

出　　处：《眼科新进展》2003年第2期86-89,共4页Recent Advances in Ophthalmology

基　　金：中国人民解放军总后勤部留学回国人员基金资助 (编号 :97H2 6 )~~

摘　　要：目的　研究糖基化对 α-晶状体蛋白分子伴侣活性的作用。方法　分离牛晶状体α-晶状体蛋白 ,分别与 0 .5 mol· L- 1 果糖和 0 .5 m ol· L- 1 葡萄糖在 37℃温育 ,在第 0、2 4、32天测定 380 nm的光吸收值和 40 0 nm非色氨酸荧光值 ,高压液相色谱 ( high performanceliquid chrom atography,HPL C)和 SDS- PAGE评价蛋白质交联程度 ,采用过氧化氢酶( catalase,CAT)和βL-晶状体蛋白的热凝聚光散射值 ,作为α-晶状体蛋白的分子伴侣活性指标。结果　果糖和葡萄糖可导致时间依赖性 α-晶状体蛋白在 380 nm吸收值的增加 ,非色氨酸荧光值升高 ;HPL C和 SDS- PAGE提示糖与α-晶状体蛋白形成交联复合物。果糖较葡萄糖作用明显。糖基化导致 α-晶状体蛋白抑制 CAT和 βL-晶状体蛋白热凝聚作用降低 ,孵育第 2 4天 ,葡萄糖组α-晶状体蛋白分子伴侣活性分别降低约 12 %和 19% ,果糖组约7%和 9% .结论　糖基化导致 α-晶状体蛋白形成高分子聚合物、凝聚、交联 ,分子伴侣活性丧失 ,这在老化和糖尿病性白内障形成过程中起重要作用。ObjectiveTo evaluate the effect of glycation on α-crystallin molecular chaperone activity.Methodsα-crystallin was separated from calf lenses and then was incubated with 0.5 mol·L -1 fructose and 0.5 mol·L -1 glucose at 37℃ respectively. The absorbance at 380nm and non-tryptophan fluorescence at 400nm were observed after 0? 24?32 days incubation. The extent of crosslinking was detected by high performance liquid chromatography (HPLC) and SDS-PAGE. The chaperone activity of α-crystallin was assayed by measuring heat-induced aggregation and scattering of catalase and β L-crystallin. ResultsThe absorbance of α-crystallin glycated by fructose and glucose at 380 nm and non-tryptophan fluorescence was increased in time-dependent manner. HPLC and SDS-PAGE results showed that glycation led to crosslinking formation of α-crystallin. Fructose presented more effective cross-linked α-crystallin than glucose. Glycation induced by glucose and fructose decreased the preventive effect of α-crystallin against thermal aggregation catalase and β L-crystallin compared with control proteins. After 24 days incubation, the preventive ability in α-crystallin incubated with glucose was diminished approximately 12% by catalase aggregation assay and 19% by β L-crystallin aggregation assay, and that with fructose was roughly 7% and 9% respectively. Chaperone activity was slightly decreased in fructose incubation. ConclusionGlycation of α-crystallin causes the formation of high molecular weight, aggregates and crosslinking, and in turn lead to reduction of its chaperone activity, which may play a significant role in the development of cataract associated with aging and diabetes.

关 键 词：Α-晶状体蛋白 分子伴侣 糖基化 白内障 糖尿病 

分 类 号：Q51[生物学—生物化学] R392.11[医药卫生—免疫学]