van den Berg G J, van den Hamer C J
J Inorg Biochem. 1985 Aug;24(4):289-97. doi: 10.1016/0162-0134(85)85057-1.
Cultured rat hepatoma cells (HTC-cells) were used to study the uptake of copper and zinc from a minimal salt-glucose medium, supplemented with albumin from different species or with ovalbumin. Competitive equilibrium dialysis showed that at low molar ratios of metal/protein (less than 1) the affinity for copper of human and bovine albumin was about equal, but that of dog albumin or ovalbumin was much lower. Only a small difference in affinity for zinc could be detected between human albumin and ovalbumin. Supplementing the medium with the different proteins the rate of copper uptake in the cell at a given molar Cu/protein ratio increased as follows: human albumin congruent to bovine albumin less than dog albumin less than ovalbumin. When the molar Cu/protein ratio was increased, a discontinuity was seen with all three albumin species at a ratio of about 1. In contrast, the zinc uptake mimics that of Cu/ovalbumin, and no discontinuity was observed using different molar Zn/protein ratios. These results indicate that the rate of copper and zinc uptake depends strongly on its affinity for the protein: a low affinity leads to a high uptake. The results suggest further that at physiologic concentrations zinc is taken up by a mechanism different from that for copper.
培养的大鼠肝癌细胞（HTC细胞）被用于研究从添加了不同物种白蛋白或卵清蛋白的最低盐 - 葡萄糖培养基中摄取铜和锌的情况。竞争性平衡透析表明，在低金属/蛋白质摩尔比（小于1）时，人白蛋白和牛白蛋白对铜的亲和力大致相等，但狗白蛋白或卵清蛋白的亲和力则低得多。在人白蛋白和卵清蛋白之间，仅检测到对锌的亲和力有微小差异。用不同蛋白质补充培养基后，在给定的铜/蛋白质摩尔比下，细胞摄取铜的速率增加如下：人白蛋白≈牛白蛋白＜狗白蛋白＜卵清蛋白。当铜/蛋白质摩尔比增加时，在约1的比例下，所有三种白蛋白都出现了不连续性。相比之下，锌的摄取情况类似于铜/卵清蛋白的情况，使用不同的锌/蛋白质摩尔比未观察到不连续性。这些结果表明，铜和锌的摄取速率强烈依赖于其对蛋白质的亲和力：低亲和力导致高摄取。结果还进一步表明，在生理浓度下，锌的摄取机制与铜不同。
