On vitamin B12-protein-complex in bovine blood.

Abstract

1. The authors have found in the previous experiments that the relative amount of free vitamin B12 and its bound form in serum is changeable according to various conditions. This experiment was retested in the present experiment with the blood added with vitamin B12 by dialyzing with animal membrane against barbiturate buffer, pH 8.6. The bound vitamin was found to be 3.30-3.80mγ per ml of bovine blood.2. The distribution of bound B12 in bovine serum was studied by both paper electrophoresis and bioautography and the vitamin-binding ability of γ-globulin was found to be higher than that of albumin or β-globulin.3. It was found that 50per cent of the vitamin B12 in bovine blood was found in red blood cells, about 75per cent of the vitamin being in a bound form. 10g of freshly prepared bovine erythrocytes were found to contain 8.5mγ of the vitamin in endosama and 0.69mγ in stroma. Repeated experiments of paper electrophoresis and microbioassay showed that the vitamin in bovine endosoma may probably exist in the form of B12-globin-complex.