Control of Pyrimidine Biosynthesis in Human Lymphocytes

Control of pyrimidine biosynthesis in Pseudomonas aeruginosa.

The pathway of pyrimidine biosynthesis in Pseudomonas aeruginosa has been shown to be the same as in other bacteria. Twenty-seven mutants requiring uracil for growth were isolated and the mutant lesions were identified. Mutants lacking either dihydroorotic acid dehydrogenase, orotidine monophosphate pyrophosphorylase, orotidine monophosphate decarboxylase, or aspartic transcarbamylase were isol...

Characterization of Pyrimidine Biosynthesis

Control of pyrimidine biosynthesis in human lymphocytes. Simultaneous increase in activities of glutamine-utilizing carbamyl phosphate synthetase and aspartate transcarbamylase in phytohemagglutinin-stimulated human peripheral lymphocytes and their enzyme co-purification.

Human peripheral lymphocytes were incubated in the presence of Phaseolus vulgaris phytohemagglutinin. ACtivities of both glutamine-utilizing carbamyl phosphate synthetase (EC 2.7.2.5) and aspartate transcarbamylase (EC 2.1.3.2), the initial enzymes of the de nouo pathway for pyrimidine biosynthesis, increased simultaneously during the blastogenesis of lymphocytes. A very close connection betwee...

Variablity of chromosomal radioadaptive response in human lymphocytes.

Background : There are growing evidences for chromosomal radioadaptive response in human lymphocytes . Highly variable inter- and intra-individual responses have been reported. Some individuals are non-responders and even in some donors the frequency of chromatid aberrations induced by a challenge dose increases by pre-exposure to an adapting dose. It has been proposed that the lack of radioada...

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 resul...