REGULATORY PROPERTIES OF HISTIDASE FROM PSEUDOMONAS-PUTIDA

Histidase from Pseudomonas putida was inhibited by a variety of nucleotides and nucleosides. Guanine, xanthine and cytosine derivatives were the most potent inhibitors, with adenine, hypoxanthine and uracil derivatives considerably less inhibitory; the extent of phosphorylation was relatively unimportant. Kinetically, the actions of ATP, GTP and GMP were similar. Each exhibited an apparent non-competitive inhibition towards histidine with multiple binding sites. It was concluded that histidase activity could be controlled by variations in the total intracellular nucleotide concentration, thereby regulating C1 unit production for purine biosynthesis. © 1979.