Cyanocobalamin amides

Figure 1 Schematic representation of the molecular structure, numbering of atoms, and designations of pyrrole rings of cobalamins. R = Me is methyl B12 R = Ado is adenosyl-cobalamin (coenzyme B12) X = CN is cyanocobalamin (vitamin B12). Five-membered rings are labeled A-D, and the amide side-chains are labeled a-g.

Hydrolysis of cyanocobalamin for 5 min with concentrated hydrochloric acid liberated the nucleotide moiety the aminopropanol fragment was retained and there was little effect on either the cyanide group or the amide linkages. This cobalt-containing hydrolytic fragment is identical with Factor B, a microbiologically active compound from fecal material. Further hydrolysis of Factor B yielded corresponding mono-, di-, and tri-carboxylic acids in which the nucleotide moiety was absent. These could also be converted to the parent compound. Factor B, by way of the intermediate mixed anhydride and treatment with ammonia. 

The heptacarboxylic acid derived from cyanocobalamin by converting all amide groups to carboxyl groups is designated cobyrinic acid (IX). 

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