Carbamyl phosphate synthetase biosynthesis

Tl. Tatibana, M., and Ito, K., Carbamyl phosphate synthetase of the hematopoietic mouse spleen and the control of pyrimidine biosynthesis. Biochem. Biophys. Res. Commun. 26, 221-227 (1967). 

The intramitochondrial location of the arginine-specific carbamyl phosphate synthetase in N. crassa has the additional advantage of assuring separate pools of carbamyl phosphate for arginine and pyrimidine biosynthesis (41). Since this precludes the utilization of carbamyl phosphate produced in the course of arginine biosynthesis by aspartate transcarbamylase and of the pyrimidine-specific carbamyl phosphate by ornithine transcarbamylase, the control of these reac-... 

The Ornithine Urea Cycle Biosynthesis and Regulation of Carbamyl Phosphate Synthetase I and Ornithine Transcar-... 

The cycle starts with carbamyl phosphate formation (this reaction was discussed in the section on pyrimidine biosynthesis). Carbamyl phosphate synthetase catalyzes the condensation of active CO2 with NH4 to yield carbamyl phosphate, a precursor of pyrimidines and urea. 

The enzymes discussed in the previous sections (carbamyl phosphate synthetase, ornithine transcarbamylase, argininosuccinate synthetase, cleavage enzyme, and arginase) constitute the known enzymic steps in the sequence of reactions leading to the biosynthesis of urea in ureotelic animals in accordance with the cycle originally proposed by Krebs and Hen-seleit (458). A summary scheme showing the steps in this cycle and the relationship of some of the intermediates to other systems is shown in Fig. 2. 

---