Carbamoyl Phosphate

Carbamoyl phosphate is an intermediate in arginine, urea, and pyrimidine biosynthesis. Carbamoyl phosphate is created in reactions 1 and 2 below.

1. NH 4+ + CO 2 + 2 ATP <=> Carbamoyl Phosphate + 2 ADP + Pi (catalyzed Carbamoyl Phosphate Synthetase)

2. Glutamine + ATP + HCO 3- <=> Glutamate + Carbamoyl phosphate + ADP (catalyzed by Carbamoyl Phosphate Synthetase II)

3. Carbamoyl phosphate + Ornithine <=> Citrulline + Pi (catalyzed by Ornithine Transcarbamoylase)

4. Aspartate + Carbamoyl Phosphate <=> Carbamoyl aspartate (catalyzed by Aspartate Transcarbamoylase)

Carbamoyl phosphate is an allosteric inhibitor of glutamine synthetase, an enzyme with a central role in nitrogen metabolism in the cells.

See also: Urea Cycle Reactions, Figure 11.35, Figure 22.10, Glutamine Synthetase

INTERNET LINK: Urea Cycle and Metabolism of Amino Groups