代谢
锌可以通过肺部、皮肤和胃肠系统进入人体。肠道对锌的吸收是由锌载体蛋白CRIP控制的。锌还与金属硫蛋白结合，帮助防止过量锌的吸收。锌在体内广泛分布，存在于所有组织和组织液中，尤其在肝脏、胃肠系统、肾脏、皮肤、肺、大脑、心脏和胰腺中含量较高。在血液中，锌与红细胞中的碳酸酐酶结合，也与血浆中的白蛋白、α2-巨球蛋白和氨基酸结合。白蛋白和氨基酸结合的锌可以扩散穿过组织膜。锌通过尿液和粪便排出体外。硒可能通过吸入和摄入被吸收，一些硒化合物也可能通过皮肤被吸收。一旦进入人体，硒主要分布到肝脏和肾脏。硒是一种必需的微量元素，是谷胱甘肽过氧化物酶、碘甲状腺原氨酸5'-脱碘酶和硫氧还蛋白还原酶的组成部分。有机硒首先代谢为无机硒。无机硒逐步还原为中间氢硒化物，然后转化为硒磷酸和硒半胱氨酸tRNA并整合入硒蛋白，或者转化为硒化物的甲基化代谢物后随尿液排出。元素硒在排泄前也会被甲基化。硒主要通过尿液和粪便排出，但某些硒化合物也可能通过呼气排出。
Zinc can enter the body through the lungs, skin, and gastrointestinal tract. Intestinal absorption of zinc is controlled by zinc carrier protein CRIP. Zinc also binds to metallothioneins, which help prevent absorption of excess zinc. Zinc is widely distributed and found in all tissues and tissues fluids, concentrating in the liver, gastrointestinal tract, kidney, skin, lung, brain, heart, and pancreas. In the bloodstream zinc is found bound to carbonic anhydrase in erythrocytes, as well as bound to albumin, _2-macroglobulin, and amino acids in the the plasma. Albumin and amino acid bound zinc can diffuse across tissue membranes. Zinc is excreted in the urine and faeces. Selenium may be absorbed through inhalation and ingestion, while some selenium compounds may also be absorbed dermally. Once in the body, selenium is distributed mainly to the liver and kidney. Selenium is an essential micronutrient and is a component of glutathione peroxidase, iodothyronine 5'-deiodinases, and thioredoxin reductase. Organic selenium is first metabolized into inorganic selenium. Inorganic selenium is reduced stepwise to the intermediate hydrogen selenide, which is either incorporated into selenoproteins after being transformed to selenophosphate and selenocysteinyl tRNA or excreted into the urine after being transformed into methylated metabolites of selenide. Elemental selenium is also methylated before excretion. Selenium is primarily eliminated in the urine and feces, but certain selenium compounds may also be exhaled. (L619, L49)
来源:Toxin and Toxin Target Database (T3DB)
