Differential Binding to Sepharose-Con A of B12-Binding Proteins from Human Gastric Juice

Summary Human gastric juice was found to contain at least two vitamin B12 binding substances. One of the proteins which formed a complex with B12 was found to bind to a column containing Sepharose-ConA. Since the protein which bound to Sepharose-ConA was absent in the gastric juice of pernicious anemia patients it was concluded that this protein was intrinsic factor. The ability of intrinsic factor to bind to Sepharose-ConA offers a potential means by which intrinsic factor could be separated from other B12 binding proteins in gastric juice. The ConA binding properties of intrinsic factor might be exploited in the development of a diagnostic test for pernicious anemia. The assistance of Mr. Hiroshi Takahashi during portions of the work is gratefully acknowledged. Miss Jessica Ferrari is also thanked for providing gastric juice samples. Thir work was supported by G.D. Searle Grant No. 443918-58005 and in part by V.A. RE TR-48 and V.A. Research Grant.