Mono-Substituted Vit. B 12 Amides. II. Further Inhibition Study. ∗ †

Summary

The anilide, ethylamide, ethylamide monoacid, and di-(ethylamide) derivative of B₁₂ inhibit cobalamin utilization by O. malhamensis and E. coli. The monobasic acid inhibits B₁₂ utilization by E. coli, but not by O. malhamensis: the reverse is true for the dibasic acid. Methylamide and carbanilide derivatives are utilized as well as true B₁₂; all compounds are as active as true B₁₂ for E. gracilis and L. leichmannii. In E. coli, suboptimal levels of methionine in presence of B₁₂ amides and acids give increasing growth with increasing concentrations of B₁₂ derivatives; neither methionine nor B₁₂ acid and amide, when added alone, permit growth.