Aspartate transcarbamylase bacterial

Animal and bacterial enzymes that utilize or synthesize carbamyl phosphate have activity with acetyl phosphate. Acyl phosphatase hydrolyzes both substrates, and maybe involved in the specific dynamic action of proteins. Ornithine and aspartic transcarbamylases also synthesize acetylornithine and acetyl aspartate. Finally, bacterial carbamate kinase and animal carbamyl phosphate synthetase utilize acetyl phosphate as well as carbamyl phosphate in the synthesis of adenosine triphosphate. The synthesis of acetyl phosphate and of formyl phosphate by carbamyl phosphate synthetases is described. The mechanism of carbon dioxide activation by animal carbamyl phosphate synthetase is reviewed on the basis of the findings concerning acetate and formate activation. 

Preparations of aspartate transcarbamylase from dog intestinal mucosa, rat liver, E. coli B, and E. coli 185-482 can utilize acetyl-P, although at much slower rates than carbamyl-P. The ratio of carba-myl-P to acetyl-P transfer is of the order of 20 with mammalian enzymes, and 400 with bacterial preparations (as indicated above, the ratios of carbamyl-P to acetyl-P transferring activity are also smaller with mammalian than with bacterial ornithine transcarbamylase). 

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