Pyrimidine biosynthesis de novo in M. leprae

Mycobacterium leprae can synthesise pyrimidines de novo. Although pyrimidine synthesis could not be detected in intact bacteria, extracts contained all four enzymes unique to the de novo pathway which are detectable in mycobacteria by the methods used. Inhibition of aspartate transcarbamylase by UTP and ATP suggested that lack of pyrimidine synthetic activity in whole M. leprae could be a result of strong feedback inhibition.