KINETICS OF B12, INTRINSIC FACTOR, AND OTHER PROTEINS

这个项目的长期目标是准确地描述 钴胺与肠道必需大分子的相互作用 这种维生素的吸收、运输和细胞摄取以及发育 更易应用的识别、测量和使用的放射分析方法 研究生理性和非生理性钴蛋白的代谢。 为了实现这些目标，我们有以下具体目标：a) 描述内在因子(IF)-钴胺的作用机制 复合体与IF受体蛋白结合，促进 钴胺的内化。为此，我们将使用放射免疫分析和 回肠上皮细胞的免疫细胞化学分析。B)确定和 钴胺结合蛋白免疫活性形式的表征 经凝胶过滤和离子交换层析分离 特异的RIA来鉴定这些蛋白质。C)发展放射免疫分析 钴胺特定生理形态的测量技术及应用 这些测定辅酶浓度的分析方法 直接在血液和组织提取液中。D)分离和鉴定 血浆中皮质醇类化合物的非生理形态的色谱分析 分离和配基结合放射分析。E)发展 放射免疫酶分析法研究两种生理活性物质的合成 辅酶，腺苷钴胺和甲钴胺，并表征 这些生物合成过程所需的酶。 在这个项目中获得的信息和开发的技术将 加深对钴胺吸收障碍的认识 药物、毒素和肝病可能发生的运输；以及 测量钴胺辅酶的分析技术可以提供远 确定获得性和遗传性细胞疾病的更简单方法 钴胺辅酶合成。

The long term objectives of this project are to characterize precisely the interaction of cobalamin with macromolecules required for intestinal absorption, transport, and cellular uptake of this vitamin and to develop more readily applicable radioassays by which to identify, measure, and study the metabolism of the physiologic and non-physiologic cobalamins. Toward these objectives, we have the following specific aims: a) To characterize the mechanism by which the intrinsic factor (IF)-cobalamin complex binds to the IF-receptor protein and facilitates the internalization of cobalamin. For this we will use radioimmunoassay and immunocytochemical analysis of ileal epithelial cells. b) To identify and characterize immunoreactive forms of the cobalamin binding proteins fractionated by gel-filtration and ion exchange chromatography using specific RIA to identify these proteins. c) To develop radioimmunoassay techniques to measure the specific physiologic forms of cobalamin and use these analytical methods to measure the concentration of these coenzymes directly in blood and tissue extracts. d) To isolate and characterize the nonphysiologic forms of corrinoid compounds in plasma using chromatographic separation and ligand binding radioassays. e) To develop radioimmunoenzymatic assays to study the synthesis of the two physiologic coenzymes, adenosyl cobalamin and methyl cobalamin and to characterize the enzymes required for these biosynthetic processes. The information obtained and the techniques developed in this project would extend our understanding of the disorders of cobalamin absorption and transport which may occur with drugs, toxins and liver disease; and the analytical techniques to measure cobalamin coenzymes could provide a far simpler method for determining acquired and inherited cellular disorders of cobalamin coenzyme synthesis.