Oh S H, Nakaue H, Deagen J T, Whanger P D, Arscott G H
J Nutr. 1979 Oct;109(10):1720-9. doi: 10.1093/jn/109.10.1720.
Two experiments were conducted with Hubbard broiler chicks on the metabolism of high levels of dietary zinc. In the first experiment, chicks were fed a basal diet or the basal diet plus 500, 1,000, 2,000 or 4,000 ppm zinc, and in the second experiment chicks were fed the basal diet or the basal diet plus 1,000, 2,000, 4,000, 8,000 or 16,000 ppm zinc, using zinc acetate. Zinc was found to be associated with 4 peaks when the cytosols from tissues (liver, kidney, pancreas and intestinal mucosa) were eluted through columns of G-75 Sephadex. Although the zinc content of all four peaks increased with increased zinc content of the diet, the greatest elevation occurred in metallothionein (MT). This protein was purified from all four tissues (liver, kidney, pancreas and intestinal mucosa) and the amino acid analysis revealed the presence of about 30% cysteine. Zinc accumulated to the greatest extent (microgram in MT/g tissue) in MT of the pancreas. The zinc in MT disappeared very rapidly when chicks which had been fed a diet containing high levels of zinc were fed a low zinc diet, indicating the extreme lability of this metal in this protein. The results suggest the involvement of MT in zinc homeostasis.
用哈伯德肉鸡雏鸡进行了两项关于高剂量日粮锌代谢的实验。在第一项实验中，雏鸡被喂食基础日粮或基础日粮加500、1000、2000或4000 ppm的锌，在第二项实验中，雏鸡被喂食基础日粮或基础日粮加1000、2000、4000、8000或16000 ppm的锌，使用的是乙酸锌。当来自组织（肝脏、肾脏、胰腺和肠黏膜）的胞质溶胶通过G - 75葡聚糖凝胶柱洗脱时，发现锌与4个峰相关。尽管所有4个峰的锌含量都随着日粮锌含量的增加而增加，但金属硫蛋白（MT）中的升高最为显著。这种蛋白质从所有4种组织（肝脏、肾脏、胰腺和肠黏膜）中被纯化出来，氨基酸分析显示存在约30%的半胱氨酸。锌在胰腺的MT中积累到最大程度（微克/克组织）。当喂食高锌日粮的雏鸡改喂低锌日粮时，MT中的锌消失得非常迅速，这表明这种金属在该蛋白质中的极端不稳定性。结果表明MT参与锌的体内平衡。
