Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

carbamoyl-phosphate synthase (glutamine-hydrolysing)

Name from literature

carbamoyl phosphate synthase

Pathway from literature

the de novo UTP biosynthetic pathway

Pathway from KEGG

Amino Acid Metabolism; Glutamate metabolism; map00251

Nucleotide Metabolism; Pyrimidine metabolism; map00240


Rat (10116)


The product carbamoyl phosphate is an intermediate in the biosynthesis of arginine and the pyrimidine nucleotides [4]. The enzyme from Escherichia coli has three separate active sites, which are connected by a molecular tunnel that is almost 100 A in length [8]. The amidotransferase domain within the small subunit of the enzyme hydrolyses glutamine to ammonia via a thioester intermediate. The ammonia migrates through the interior of the protein, where it reacts with carboxy phosphate to produce the carbamate intermediate. The carboxy-phosphate intermediate is formed by the phosphorylation of bicarbonate by ATP at a site contained within the N-terminal half of the large subunit. The carbamate intermediate is transported through the interior of the protein to a second site within the C-terminal half of the large subunit, where it is phosphorylated by another ATP to yield the final product, carbamoyl phosphate [6].

Rate-limiting Description

"Assuming that plasma NH3 levels reflect those in mitochondria, the NH3 concentration yielding half-maximal rates of urea synthesis (close to 2 microM) was in the same range as Km for the rate-limiting step in ureagenesis, carbamoyl phosphate synthetase (EC" (3812736)

"The data indicate that the expression of urea cycle enzymes, in particular that of carbamoyl phosphate synthetase which is the rate-limiting step, is up-regulated by partial hepatectomy." (7608487)


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  Last Modified: 2009-03-24  
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