【摘要】 我们用Na⁷⁵₂SeO₃皮下注射诱发大鼠产生白内障后,观察⁷⁵Se在房水及晶状体中的分布。发现注射后4小时内,⁷⁵Se迅速进入眼内,产生白内障的大鼠晶状体中⁷⁵Se较多,而注射后未产生白内障的大鼠透明晶状体中⁷⁵Se进入很少。经三氯醋酸处理后,⁷⁵Se主要在沉淀部分,经巯基乙醇处理后,⁷⁵Se转移到上清液中,经Se-phadex G-200柱层析可见⁷⁵Se与α、β_H、β_L、γ晶体蛋白都结合。这提示⁷⁵Se可能是与晶体蛋白质中的半胱氨酸残基的巯基相连,从而使蛋白质交联起来,导致晶状体中高分子量蛋白质的形成,引起光线的散射,而表现为白内障。更多还原

【Abstract】 We have studied the distribution of Se in aqueous humor and lens, and also the role played by Se in the formation of cataract induced in rats by subcutaneous injection of radioactive sodium selenite (Na275SeO3). After injection, the activity of 75Se appeared in both aqueous humor and lens within 4 hrs. In rats with ca-taracts the amountt of 75Se was always high in the lens, but in rats without cataract, the value was low in the lens. In aqueous humor, the level of radioactivity in the non-cataractous animals showed a rather rapid metabolic rate, but in animals with cataract the metabolic rate was always slower than the former. It is necessary to point out that large part of Se in cataractous lens was firmly combined with crystallins by substituting the hydrogen atoms of sulfhydryl groups of cysteine residues in different protein molecules which were then cross-linked,resulting in opacity of the lens. This was proved by the fact that after treatment of the 75Se-containing proteins with mercaptoethanol followed by TCA precipitation, the radioactivity of the protein precipitate was greatly decreased with a corresponding increment in the supernatant. We have also found that all four crystallins (α,βH, βL and γ crystallins) contained sulfhydryl groups, and the SH content in the βH-and γ-crystallins Were somewhat higher than the other as indicated by the distribution of 75Se in the soluble proteins.更多还原