Isolation of Methylcobalamin from Natural Source Material

INVESTIGATION of the form of vitamin B12 in human blood plasma by chromatographic-bioautographic analysis revealed as the major component a ‘fourth factor’ besides DMB coenzyme (coenzyme B12) and traces of hydroxo-cobalamin and cyanocobalamin1. This factor was also found in liver, E. coli and Streptomyces rimosus. In order to identify this analogue we have tried to isolate it from a natural source material rich in coenzyme B12 and have found good evidence that this analogue is methyl-cobalamin. Methylcobalamin was prepared by partial synthesis a couple of years ago2 and was shown by Guest et al.3 to be active in the enzymatic synthesis of methionine by extracts of an Escherichia coli mutant. However, methylcobalamin has not previously been shown to occur naturally.