Carbamoyl phosphate is an
anion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
of biochemical significance. In land-dwelling animals, it is an intermediary metabolite in
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...
disposal through the
urea cycle
The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea (NH2)2CO from ammonia (NH3). Animals that use this cycle, mainly amphibians and mammals, are called ureotelic.
The urea cycle converts hi ...
and the synthesis of
pyrimidine
Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The othe ...
s. Its enzymatic counterpart, carbamoyl phosphate synthetase I (CPS I), interacts with a class of molecules called
sirtuin
Sirtuins are a family of signaling proteins involved in metabolic regulation. They are ancient in animal evolution and appear to possess a highly conserved structure throughout all kingdoms of life. Chemically, sirtuins are a class of proteins ...
s, NAD dependent protein deacetylases, and ATP to form carbamoyl phosphate. CP then enters the urea cycle in which it reacts with
ornithine
Ornithine is a non-proteinogenic amino acid that plays a role in the urea cycle. Ornithine is abnormally accumulated in the body in ornithine transcarbamylase deficiency. The radical is ornithyl.
Role in urea cycle
L-Ornithine is one of the prod ...
(a process catalyzed by the enzyme
ornithine transcarbamylase
Ornithine transcarbamylase (OTC) (also called ornithine carbamoyltransferase) is an enzyme () that catalyzes the reaction between carbamoyl phosphate (CP) and ornithine (Orn) to form citrulline (Cit) and phosphate (Pi). There are two classes of OT ...
) to form
citrulline
The organic compound citrulline is an α-amino acid. Its name is derived from '' citrullus'', the Latin word for watermelon. Although named and described by gastroenterologists since the late 19th century, it was first isolated from watermelon in 1 ...
.
Production
It is produced from
bicarbonate
In inorganic chemistry, bicarbonate ( IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula .
Bicarbonate serves a crucial bioch ...
,
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogeno ...
(derived from
amino acids), and
phosphate
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid .
The phosphate or orthophosphate ion is derived from phosph ...
(from
ATP
ATP may refer to:
Companies and organizations
* Association of Tennis Professionals, men's professional tennis governing body
* American Technical Publishers, employee-owned publishing company
* ', a Danish pension
* Armenia Tree Project, non ...
).
The synthesis is catalyzed by the enzyme
carbamoyl phosphate synthetase
Carbamoyl phosphate synthetase catalyzes the ATP-dependent synthesis
of carbamoyl phosphate from glutamine () or ammonia () and bicarbonate. This enzyme catalyzes the reaction of ATP and bicarbonate to produce carboxy phosphate and ADP. Carbox ...
.
This uses three reactions as follows:
* + ATP → ADP + (carboxyl phosphate)
* + NH
3 + OH
− → +
−O–C(O)NH2 + H
2O
*
−O–C(O)NH
2 + ATP → ADP +
Clinical significance
A defect in the CPS I enzyme, and a subsequent deficiency in the production of carbamoyl phosphate has been linked to
hyperammonemia
Hyperammonemia is a metabolic disturbance characterised by an excess of ammonia in the blood. It is a dangerous condition that may lead to brain injury and death. It may be primary or secondary.
Ammonia is a substance that contains nitrogen. It is ...
in humans.
See also
*
Ornithine transcarbamylase
Ornithine transcarbamylase (OTC) (also called ornithine carbamoyltransferase) is an enzyme () that catalyzes the reaction between carbamoyl phosphate (CP) and ornithine (Orn) to form citrulline (Cit) and phosphate (Pi). There are two classes of OT ...
*
Citrulline
The organic compound citrulline is an α-amino acid. Its name is derived from '' citrullus'', the Latin word for watermelon. Although named and described by gastroenterologists since the late 19th century, it was first isolated from watermelon in 1 ...
*
Urea Cycle
The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea (NH2)2CO from ammonia (NH3). Animals that use this cycle, mainly amphibians and mammals, are called ureotelic.
The urea cycle converts hi ...
References
Bibliography
*
*"SIRT5 Deacetylates Carbamoyl Phosphate Synthetase 1 and Regulates the Urea Cycle". ''Cell.'' 137 (3): 560–570. 2009-05-01. doi:10.1016/j.cell.2009.02.026. ISSN 0092-8674.
{{Urea cycle
Organophosphates
Carbamates
Acid anhydrides
Urea cycle