Rothenberg S P
J Clin Invest. 1968 Apr;47(4):913-23. doi: 10.1172/JCI105783.
The precipitate which resulted when (57)CoB(12) bound to normal human gastric juice was subjected to a 15% concentration of Na(2)SO(4) contained virtually no radioactivity. However, after in vivo incubation of the gastric juice-(57)CoB(12) mixture in the distal ileum of the guinea pig, the dialyzed extract of the washed mucosa contained a fraction of (57)CoB(12) which was precipitated at 15% Na(2)SO(4). In addition, in vitro incubation of gastric juice-(57)CoB(12) with an extract of the ileal mucosa or brush border membranes also resulted in the formation of a 15% Na(2)SO(4)-insoluble fraction which contained (57)CoB(12). The formation of this (57)CoB(12)-containing insoluble fraction did not occur or was diminished by (a) addition of an excess of B(12)-free normal human gastric juice. (b) reducing the incubation pH to 2, (c) incubating the mixture at 4 degrees C, (d) pretreating the ileal extract at 56 degrees C for 30 min, (e) incubating the reaction in sodium EDTA but not calcium EDTA, (f) incubating gastric juice-(57)CoB(12) with an extract of jejunal mucosa. Sephadex gel filtration was used to demonstrate that the factor in the ileal extract which reacted with the gastric juice-(57)CoB(12) filtered through G-100 and G-200 columns in the excluded volume. When the ileal extract obtained after in vivo incubation with gastric juice-(57)CoB(12) was subjected to starch gel electrophoresis one peak of radioactivity remained at the origin and another moved anodally. Eluates of each peak reacted with anti-intrinsic factor antibody indicating that at least the immunologically reacting portion of the intrinsic factor molecule was present in two fractions with different electrophoretic mobility.These studies indicate that immunologically intact intrinsic factor can be extracted from the ileum after in vivo incubation with gastric juice-(57)CoB(12), and that a macromolecular factor is present in the distal ileal mucosa which binds intrinsic factor both in vitro and in vivo, changing its solubility and electrophoretic properties. It is suggested that this ileal binding factor is the previously postulated intestinal receptor for intrinsic factor.
当（57）钴维生素B12与正常人胃液结合产生的沉淀物，在15%硫酸钠浓度下几乎不含放射性。然而，在豚鼠回肠远端对胃液 - （57）钴维生素B12混合物进行体内孵育后，洗涤过的黏膜的透析提取物中含有一部分（57）钴维生素B12，其在15%硫酸钠中沉淀。此外，胃液 - （57）钴维生素B12与回肠黏膜提取物或刷状缘膜进行体外孵育，也会导致形成一个含有（57）钴维生素B12的15%硫酸钠不溶部分。这种含（57）钴维生素B12的不溶部分的形成不会发生或会因以下情况而减少：（a）加入过量不含维生素B12的正常人胃液；（b）将孵育pH值降至2；（c）在4℃孵育混合物；（d）将回肠提取物在56℃预处理30分钟；（e）在乙二胺四乙酸钠而非乙二胺四乙酸钙中孵育反应；（f）胃液 - （57）钴维生素B12与空肠黏膜提取物孵育。使用葡聚糖凝胶过滤法证明，回肠提取物中与胃液 - （57）钴维生素B12反应的因子在排除体积中通过G - 100和G - 200柱。当在体内与胃液 - （57）钴维生素B12孵育后获得的回肠提取物进行淀粉凝胶电泳时，一个放射性峰留在原点，另一个向阳极移动。每个峰的洗脱物与抗内因子抗体反应，表明内因子分子至少免疫反应部分存在于两个具有不同电泳迁移率的部分中。这些研究表明，在与胃液 - （57）钴维生素B12进行体内孵育后，可以从回肠中提取免疫完整的内因子，并且在回肠远端黏膜中存在一种大分子因子，其在体外和体内都能结合内因子，改变其溶解度和电泳性质。有人认为这种回肠结合因子是先前假设的内因子肠道受体。
