正常与患白内障大鼠晶状体中脲溶性蛋白质性质的研究

本文研究了正常及三种类型白内障大鼠晶状体中脲溶性蛋白质的含量及性质的变化,发现在每种类型白内障晶状体中,水溶性蛋白质均减少,水不溶性蛋白质则都相对增加。经SephadexG-200柱层析及SDS聚丙烯酰胺凝胶电泳发现,晶状体中脲溶性蛋白质主要是由二硫键交联而成的高分子聚合物。经巯基乙醇还原后,绝大部分高分子聚合物可分解成低分子量蛋白质,其分子量与水溶性的γ晶体蛋白相同。这提示晶状体中脲溶性蛋白质的主要成分很可能是以二硫键交联而成的γ晶体蛋白聚合物。此结果与本实验室所得白内障晶状体水溶性蛋白质的变化相吻合。

A Study of Urea Soluble Proteins of Normal and Different Cataract Lenses

Cataracts were induced by subcutaneous injection of sodium selenite and pingyangmycin and also by abdominal injection of galactose followed by supplement of this sugar in drinking water respectively. Decrease of water contents in all these three kinds of cataractous lenses at different levels were observed. Decrease of water soluble proteins and increase of urea soluble proteins in all these three kinds of cataractous lenses were also observed. Sephadex-G-200 gel filtration chromatogra-phy and SDS-PAGE showed that the urea soluble proteins of lenses were mainly composed of disulfide crosslinked high molecular weight protein aggregates, which were segregated into proteins of smaller molecules after treatment with mercaptoe-thanol. As the molecular weight of most smaller protein was about 20 000 which corresponded to that of γ-crystallin, it might be assumed that γ-crystallin was most likely the main component of the protein aggregates. This result was also in aggre-ment with the previous findings reported in this laboratory, the amount of γ-crysta-llin in the soluble protein decreased mainly in these cataractous lenses.