Absorption of hemoglobin iron: the role of xanthine oxidase in the intestinal heme-splitting reaction.
Absorption of hemoglobin iron: the role of xanthine oxidase in the intestinal heme-splitting reaction.
复制标题
血红蛋白铁的吸收：黄嘌呤氧化酶在肠道血红素分裂反应中的作用。
DOI：
10.1182/blood.v35.1.94.94
复制
发表时间：
1970
期刊：
影响因子：
20.3
通讯作者：
L. Weintraub
中科院分区：
文献类型：
--
作者：
R. B. Dawson;S. Rafal;L. Weintraub
从摄入的血红蛋白-59Fe中提取的血红素被带入狗的小肠粘膜上皮细胞，然后59Fe出现在与转铁蛋白结合的血浆中。在体外，在粘膜的匀浆中发现了一种物质，它能从血红蛋白底物中释放铁。因此：(1)在粘膜匀浆中加入过氧化氢酶可减少“血红素裂解”反应。相比之下，过氧化氢酶抑制剂叠氮化钠则加强了这一反应。这表明过氧化氢生成系统参与了“分解血红素”的反应。(2)存在于肠道上皮细胞中的黄嘌呤氧化酶通过其底物的氧化产生过氧化氢。在肠粘膜匀浆中加入黄嘌呤氧化酶抑制剂别嘌醇可减少“血红素裂解”反应。(3)50,000辆通用汽车的分拆。粘膜匀浆在G-200 Sephadex柱上的上清液具有与黄嘌呤氧化酶相同的洗脱体积，表明其具有类似的分子量。(4)将粘膜匀浆添加到黄嘌呤底物中会产生尿酸。这些数据表明，肠上皮细胞中的黄嘌呤氧化酶在从吸收的血红素中释放铁的过程中起着重要作用。这种酶通过产生过氧化氢来调节“亚铁血红素裂解”反应，而过氧化氢反过来氧化亚铁素环上的亚甲基桥，释放铁，形成胆绿素。
Heme from ingested hemoglobin—59Fe is taken into the epithelial cell of the small intestinal mucosa of the dog and the 59Fe subsequently appears in the plasma bound to transferrin. A substance was demonstrated in homogenates of the mucosa which releases iron from a hemoglobin substrate in vitro. Thus: (1) The addition of catalase to the mucosal homogenate reduces the "heme-splitting" reaction. In contrast, sodium azide, a catalase inhibitor, potentiates the reaction. This suggests that a peroxide generating system participates in the "heme-splitting" reaction. (2) Xanthine oxidase, an enzyme present in the intestinal epithelial cell, produces H2O2 by oxidation of its substrate. The addition of allopurinol, a xanthine oxidase inhibitor, to the intestinal mucosal homogenate diminishes the "heme-splitting" reaction. (3) Fractionation of the 50,000 Gm. supernatant of the mucosal homogenate on a G-200 Sephadex column shows the "heme-splitting" activity to have the same elution volume as xanthine oxidase, indicating a similar molecular weight. (4) The addition of a mucosal homogenate to a xanthine substrate results in the production of uric acid. These data suggest that xanthine oxidase in the intestinal epithelial cell is important in the release of iron from absorbed heme. The enzyme mediates the "heme-splitting" reaction by the generation of peroxides which, in turn, oxidize the alpha-methene bridge of the heme ring releasing iron and forming biliverdin.