代谢
铜主要通过消化道吸收，但也可以通过吸入和皮肤吸收。它通过基底外侧膜，可能是通过调节铜转运蛋白，并与血清白蛋白结合运输到肝脏和肾脏。肝脏是铜稳态的关键器官。在肝脏和其他组织中，铜以与金属硫蛋白、氨基酸以及与依赖铜的酶相关联的形式储存，然后分配通过胆汁排泄或并入细胞内和细胞外蛋白中。铜通过血浆中与血清白蛋白、铜蓝蛋白或低分子量复合物结合输送到外周组织。铜可能诱导金属硫蛋白和铜蓝蛋白的产生。膜结合的铜转运腺苷三磷酸酶（Cu-ATPase）将铜离子运输进出细胞。生理上正常的铜水平通过改变铜的吸收速率和数量、分布区域以及排泄来保持恒定。砷主要通过吸入或摄入吸收，其次是通过皮肤接触。然后它分布到全身，如有必要，将其还原为砒霜，然后通过砒霜甲基转移酶甲基化为单甲基砷（MMA）和二甲砷酸（DMA）。砷及其代谢物主要通过尿液排出。砷已知能诱导金属结合蛋白金属硫蛋白，通过结合砷和其他金属使它们生物活性失效，并作为抗氧化剂，从而减少砷和其他金属的有毒效果。
Copper is mainly absorbed through the gastrointestinal tract, but it can also be inhalated and absorbed dermally. It passes through the basolateral membrane, possibly via regulatory copper transporters, and is transported to the liver and kidney bound to serum albumin. The liver is the critical organ for copper homoeostasis. In the liver and other tissues, copper is stored bound to metallothionein, amino acids, and in association with copper-dependent enzymes, then partitioned for excretion through the bile or incorporation into intra- and extracellular proteins. The transport of copper to the peripheral tissues is accomplished through the plasma attached to serum albumin, ceruloplasmin or low-molecular-weight complexes. Copper may induce the production of metallothionein and ceruloplasmin. The membrane-bound copper transporting adenosine triphosphatase (Cu-ATPase) transports copper ions into and out of cells. Physiologically normal levels of copper in the body are held constant by alterations in the rate and amount of copper absorption, compartmental distribution, and excretion. Arsenic is absorbed mainly by inhalation or ingestion, as to a lesser extent, dermal exposure. It is then distributed throughout the body, where it is reduced into arsenite if necessary, then methylated into monomethylarsenic (MMA) and dimethylarsenic acid (DMA) by arsenite methyltransferase. Arsenic and its metabolites are primarily excreted in the urine. Arsenic is known to induce the metal-binding protein metallothionein, which decreases the toxic effects of arsenic and other metals by binding them and making them biologically inactive, as well as acting as an antioxidant. (L20, L277, L279)
来源:Toxin and Toxin Target Database (T3DB)
