Blockade of vitamin B 12-binding sites in gastric juice serum and saliva by analogues and derivatives of vitamin B 12 and by antibody to intrinsic factor

Abstract

A variety of vitamin B 12 analogues and derivatives (pseudo-vitamin B 12, anilide-B 12, aquoanilide-B 12, cobinamide, cobrynamide, 5,6-dimethylbenzimidazole and five different cobaloxime compounds) were tested for their ability to reduce the unsaturated vitamin B 12-binding capacity of (1) gastric juice, (2) serum and (3) saliva. The effect of these substances on specific binders in body fluids tested, was determined by rapid DEAE-cellulose chromatography. 1. 1. Gastric juice: All vitamin B 12-like substances, except 5,6-dimethylbenzimidazole and cobaloximes, bound well to non-intrinsic factor vitamin B 12 binders in normal gastric juice. Conversely, only intrinsic factor antibody and CN-B 12 blocked radioactive vitamin B 12 binding to intrinsic factor. The B 12 binders in pernicious anemia gastric juice were not effectively blocked by either intrinsic factor antibody or analogues. This precludes the use of analogues instead of intrinsic factor antibody for assay in vitro of intrinsic factor in gastric juice, in the system described. 2. 2. Serum: Unsaturated vitamin B 12-binding capacity of normal, chronic myelogenous leukemia and pernicious anemia serum was affected very similarly, and in a pattern resembling that of the non-intrinsic factor binder of normal gastric juice, except that cobaloxime C3, was effective in reducing the serum binding of vitamin B 12. Chromatography showed equal reduction of both α-globulin and β-globulin binders. 3. 3. Analogue interference with vitamin B 12 binders in saliva was essentially similar to, but more pronounced than, the results with serum and non-intrinsic factor binder in gastric juice.