Research and Medical Services, Veterans Administration Medical Center, 91343, Sepulveda, CA.
Biol Trace Elem Res. 1984 Jun;6(3):181-93. doi: 10.1007/BF02917505.
Studies were conducted to determine the effects of zinc deficiency and excess zinc intake on the relative(65)Zn-binding activities of metallothionein (MT) and low-molecular-weight zinc-binding ligand (LMW-ZBL) in vitro and in vivo. Zinc-binding ligands of small intestine from four groups, each of five rats (normal, zinc-deficient, excess zinc injected, and excess zinc given orally), were separated by column chromatography on Sephadex G-75. The ratio of(65)Zn binding activities of MT to LMW-ZBL (MT/LMW-ZBL) in zinc-deficient rats was decreased both in vitro and in vivo compared to the control. When excess zinc was administered orally,(65)Zn-binding activity of MT was low in vitro and substantially increased in vivo. However, when excess zinc was injected intraperitoneally,(65)Zn-binding activity of MT in vitro greatly increased, but(65)Zn-binding activities of both MT and LMW-ZBL were significantly reduced in vivo as compared to the control. Based onA 280 readings of isolated MT and densities of protein bands in disc gel electrophoresis, the(65)Zn-binding activity of MT in vitro appeared to be proportional to the MT content. Hence, these data indicate that oral administration of excess zinc decreases MT whereas intraperitoneal injection of excess zinc stimulates its synthesis. Zinc deficiency has little to no effect on the intestinal MT metabolism. These results suggest that MT may be important in zinc secretion but not involved in zinc absorption; while LMW-ZBL participates both in zinc absorption and secretion.
研究旨在确定锌缺乏和过量摄入锌对金属硫蛋白（MT）和低分子量锌结合配体（LMW-ZBL）的相对（65）Zn 结合活性的影响，分别在体外和体内进行。从小肠的四个组（正常、缺锌、过量锌注射和过量锌口服）的五只大鼠中分离锌结合配体，通过 Sephadex G-75 柱色谱进行分离。与对照组相比，缺锌大鼠体内和体外 MT/LMW-ZBL 的（65）Zn 结合活性均降低。当口服给予过量锌时，MT 的（65）Zn 结合活性在体外较低，但在体内显着增加。然而，当腹腔内注射过量锌时，MT 的（65）Zn 结合活性在体外大大增加，但与对照组相比，MT 和 LMW-ZBL 的（65）Zn 结合活性在体内均显着降低。根据分离的 MT 的 A 280 读数和盘状凝胶电泳中的蛋白带密度，MT 的体外（65）Zn 结合活性似乎与 MT 含量成正比。因此，这些数据表明，口服过量锌可降低 MT，而腹腔内注射过量锌可刺激其合成。锌缺乏对肠道 MT 代谢几乎没有影响。这些结果表明 MT 可能在锌分泌中很重要，但不参与锌吸收；而 LMW-ZBL 参与锌吸收和分泌。
