Abstract
A new cyanocobalamin monocarboxylic acid (SA) possessing an acetic acid group in place of an acetamide group prepared from cyanocobalamin (CN-B_<12>) with an enzyme in Streptomyces nitrosporeus was active as a vitamin B_<12> antagonist for E. coli 215, a vitamin B_<12> by auxotroph. The compound was amidated by chemical and biological methods. SA was converted to CN-B_<12> by amidation with dry ammonia under the anhydrous condition, and when incubated with the cells of Pr. shermanii, three forms of corrinoids, SA, adenosyl-SA and DBCC, were found in the cells. However, CN-B_<12> was not observed. It was thus confirmed that this nucleotide-containing monocarboxylic acid of corrinoid could be utilized as a precursor of vitamin B12 biosynthesis by Pr. shermanii.
