Differential binding to Sepharose-Con A of B12-binding proteins from human gastric juice.

Human gastric juice was found to contain at least two vitamin B-12 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 B-12 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.