抄録
Crude preparation of cyanocobalamin, prepared from feed supplement for vitamin B_<12> fortification, was found to contain a large amount of alcohol-insoluble, red-coloured substance. The substance, tentatively designated as X-factor, could be easily separated from cyanocobalamin by chromatography on P-cellulose column or by electrophoresis on powdered-cellulose column. Microbiological activity of X-factor was about one % of that of cyanocobalamin for Escherichia coli 215,vitamin B_<12> requiring mutant. No difference was observed between X-factor and cobinamide in paper-electrophoretic mobility and in absorption spectrum. It was also found that cobalamin was biosynthesized by the addition of X-factor together with 5,6-dimethylbenzimidazole to growing culture of E. coli mutant. From these results, X-factor seems to be one of incomplete vitamin B_<12>-analogues, probably cobinamide or a compound similar to it. The above described chromatographic procedure for isolation of X-factor is thought to be very simple and useful to prepare the selected precursor for biosynthesis of cobalamins.
