Abstract
Examinations were made on the inhibitory action of two groups of 5-phenylazopyrimidines, which were classified on the basis of their antagonistic pattern on Str. faecalis, on enzymatic conversion of folic acid to the citrovorum factor by supernatant solutions of chickliver homogenates. It was demonstrated that the compounds which belong to the first group inhibited the enzymatic conversion of folic acid to the citrovorum factor by interfering in the enzymatic formation of FAH4, but the compounds of the second group exerted no influence on CF conversion.