key term - Carbamoyl phosphate

Definition

Carbamoyl phosphate is a high-energy compound that plays a crucial role in the synthesis of amino acids and nucleotides, specifically in the urea cycle and pyrimidine synthesis. It is formed from ammonia and bicarbonate through the action of the enzyme carbamoyl phosphate synthetase. This compound is vital for the detoxification of ammonia, making it essential for nitrogen metabolism.

5 Must Know Facts For Your Next Test

1. Carbamoyl phosphate is synthesized in the mitochondria of liver cells and is an important intermediary in both the urea cycle and nucleotide synthesis.
2. The formation of carbamoyl phosphate is catalyzed by carbamoyl phosphate synthetase I, an enzyme that requires N-acetylglutamate as an activator.
3. In the urea cycle, carbamoyl phosphate combines with ornithine to form citrulline, which is then converted into arginine before urea is produced.
4. In pyrimidine biosynthesis, carbamoyl phosphate serves as a substrate for the enzyme aspartate transcarbamoylase, leading to the production of carbamoyl aspartate.
5. Disruptions in the synthesis or utilization of carbamoyl phosphate can lead to metabolic disorders such as hyperammonemia or deficiencies in nucleotide synthesis.

Review Questions

• How does carbamoyl phosphate contribute to the urea cycle and what are its implications for nitrogen metabolism?
  • Carbamoyl phosphate is a key intermediate in the urea cycle, where it combines with ornithine to produce citrulline. This process is vital for detoxifying ammonia, a byproduct of protein metabolism. The conversion of ammonia into urea through the urea cycle prevents toxic accumulation and facilitates safe excretion from the body.
• What role does carbamoyl phosphate play in pyrimidine synthesis and how does this relate to overall cellular function?
  • In pyrimidine synthesis, carbamoyl phosphate acts as a substrate for aspartate transcarbamoylase to form carbamoyl aspartate, which ultimately leads to the production of pyrimidine nucleotides. These nucleotides are essential for synthesizing DNA and RNA, making carbamoyl phosphate critical for cell division and genetic information transfer.
• Evaluate the impact of impaired carbamoyl phosphate synthesis on human health and discuss potential metabolic consequences.
  • Impaired synthesis of carbamoyl phosphate can lead to conditions such as hyperammonemia due to insufficient conversion of ammonia into urea. This toxicity can result in neurological symptoms and severe complications if left untreated. Additionally, deficiencies in nucleotide production may disrupt cellular functions like DNA replication and repair, leading to compromised immune responses and increased susceptibility to various diseases.

Related terms

Urea Cycle: A series of biochemical reactions that convert ammonia into urea for excretion, thereby detoxifying excess nitrogen in the body.

Pyrimidine: A class of nitrogenous bases that includes cytosine, thymine, and uracil, which are essential components of nucleic acids.

Ammonia: A toxic nitrogenous waste product produced during the metabolism of amino acids, which needs to be converted into less harmful substances like urea.