AN IMMUNOLOGICAL AND CHROMATOGRAPHIC COMPARISON OF HUMAN INTRINSIC FACTOR AND THE ACID-STABLE GASTRIC ESTERASE VI A.

When examined by immunoelectrophoresis and double-gel diffusion, gastric acid-stable esterase (VI A) and human intrinsic factor (IF) behaved as different substances. The VI A migrated in agar-gel electrophoresis mainly as a β2/β1- globulin and IF as β1/α2-globulin. Both showed overlapping migration and diffusion near the starting point. On DEAE-chromatography IF was eluted together with VI A at 0.05-0.075 M, pH 7.0. In gel filtration experiments with Sephadex G 100 and G 200, the IF from in vivo neutralized gastric juice (NGJ) and from gastric mucosa (GM) was eluted in a definite range according to its molecular weight of 60,000. No IF was found in acid gastric juice (AGJ). Two immunologically identical variants of VI A were eluted at two different ranges when NGJ and GM were used for gel filtration. The variant of VIA with the lower molecular weight was eluted together with IF. When AGJ was used, only the VI A with the higher molecular weight was found and in an elution range quite different from that for IF. Of the purified substances, only IF showed vitamin B12-binding, which could be inhibited by serum from a patient with pernicious anaemia, and only heteroimmune serum against this B12-binding fraction contained IF antibodies of the blocking and binding types. IF and VI A proved to be biochemically and immunologically distinct proteins. [ABSTRACT FROM AUTHOR]