The regulation of aspartate transcarbamoylase activity in crude extrac
ts of the denitrifying bacterium Pseudomonas stutzeri ATCC 17588 was i
nvestigated. Under saturating substrate concentrations, putative effec
ters of this bacterial transcarbamoylase activity were screened at two
concentrations and were found to negatively control its activity. Bot
h phosphate and pyrophosphate were strongly inhibitory to the P. stutz
eri transcarbamoylase activity. Of the ribonucleotides tested as effec
ters, it was observed that ATP, UTP and GTP produced the greatest enzy
me inhibition.