The role and fate of rabbit and human transcobalamin II in the plasma transport of vitamin B12 in the rabbit.
The role and fate of rabbit and human transcobalamin II in the plasma transport of vitamin B12 in the rabbit.
复制标题
兔和人转钴胺素 II 在兔体内维生素 B12 血浆转运中的作用和命运。
DOI：
--
复制
发表时间：
1976
影响因子：
15.9
通讯作者：
R. Allen
中科院分区：
文献类型：
--
作者：
R. Schneider;R. L. Burger;C. S. Mehlman;R. Allen
先前的研究表明血浆转钴胺素II （TCII）促进多种组织对[57Co]维生素B12 （B12）的细胞摄取，但由于TCII-B12复合物蛋白部分缺乏固有的标签，因此无法确定TCII在这一过程中的作用和命运。我们用125i标记的n -琥珀酰-3-（4-羟基苯基）丙酸酯对兔和人TCII均质进行了标记，并在兔体内进行了实验。同时静脉注射125I标记的兔TCII-[57Co] B12和131I标记的牛白蛋白，125I和57Co从血浆中清除的速度（t1/2 = 1 1/2 h）比131I快，注射后1/2 h，肾、肝、脾、心、肺和小肠中125I和57Co的含量超过131I。随后，57Co仍高于131I，但125I与131I的比值在所有血浆中逐渐降低，并迅速随尿液排出。注射后1 h，血浆中57Co含量超过125I。
Previous studies have shown that plasma transcobalamin II (TCII) facilitates the cellular uptake of [57Co] vitamin B12 (B12) by a variety of tissues, but the lack of an intrinsic label on the protein moiety of the TCII-B12 complex has made it impossible to determine the role and fate of TCII during this process. We have labeled homogensous rabbit and human TCII with 125I-labeled N-succinimidyl-3-(4-hydroxyphenyl) propionate and have performed in vivo experiments in rabbits. When 125I-labeled rabbit TCII-[57Co] B12 and 131I-labeled bovine albumin were simultaneously injected intravenously, we observed that 125Iand 57Co were cleared from plasma at a faster rate (t1/2 = 1 1/2 h) than 131I and that 125I and 57Co were present in excess of 131I in the kidney, liver, spleen, heart, lung, and small intestine 1/2 h after injection. Later, 57Co remained in excess of 131I, but the ratio of 125I to 131I decreased progressively in all of these plasma and were rapidly excreted in the urine. After 1 h following injection, 57Co was present in excess of 125I in the plasma...