B12 vitamins (cobalamins). 1. Vitamins B12c and B12d

Abstract
Three red, crystalline, microbiologically and clinically active B12 vits. (B12, B12b and B12c) were isolated from Streptomyces griseus fermentations. Vit. B12c, which was produced by treatment of vit. B12b with HNO2, contained nitrite in the molecule. Removal of this nitrite group by treatment with sulfamic acid or distillation of an acidified soln. again yielded vit. B12b. Absorption spectra and other physical constants were measured.
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