Abstract
The action of tryptophanase of Escherichia coli, both wild and pyridoxineless type, was inhibited by isonicotinyl hydrazide and 2-methyl-4-amino-5-hydroxymethylpyrimidine (OMP), but not by 4-desoxypyridoxine. The inhibitory effect of INAH on the tryptophanase was prevented only by vitamin B_4 among many vitamin tested, but the inhibition due to OMP could not be checked by vitamin B_6. These findings are not consistent with those concerning the growth inhibition of lactic acid bacteria.
