Ornithine transcarbamylase

Definition

Ornithine transcarbamylase (OTC) is an enzyme that plays a crucial role in the urea cycle, which is responsible for converting ammonia into urea in the liver. It catalyzes the reaction between carbamoyl phosphate and ornithine to form citrulline, a key intermediate in the process of detoxifying nitrogenous waste. Deficiency or dysfunction of OTC can lead to severe metabolic disorders, particularly affecting the body's ability to eliminate excess nitrogen.

5 Must Know Facts For Your Next Test

1. Ornithine transcarbamylase deficiency is one of the most common urea cycle disorders, leading to the accumulation of ammonia in the bloodstream.
2. OTC is encoded by the OTC gene located on the X chromosome, which is why OTC deficiency primarily affects males more severely than females.
3. The activity of OTC is regulated by various factors including substrate availability and hormonal signals, which help maintain metabolic homeostasis.
4. In cases of OTC deficiency, symptoms can include lethargy, vomiting, and neurological issues due to high ammonia levels.
5. Treatment options for OTC deficiency may include dietary restrictions on protein intake and administration of medications that help remove ammonia from the body.

Review Questions

• How does ornithine transcarbamylase contribute to the detoxification process in the body?
  • Ornithine transcarbamylase contributes to detoxification by facilitating a critical step in the urea cycle. It catalyzes the reaction between carbamoyl phosphate and ornithine to produce citrulline. This conversion helps convert toxic ammonia into urea, which can then be excreted by the kidneys. Without adequate OTC function, ammonia accumulates, leading to toxicity.
• What are the implications of ornithine transcarbamylase deficiency on overall metabolic health?
  • The deficiency of ornithine transcarbamylase disrupts normal urea cycle function, leading to an inability to efficiently eliminate nitrogenous waste. This results in hyperammonemia, which can cause severe neurological damage and potentially be life-threatening. Managing this condition requires careful monitoring and treatment strategies to prevent ammonia build-up and associated health complications.
• Evaluate the potential genetic aspects of ornithine transcarbamylase deficiency and its impact on treatment options.
  • Ornithine transcarbamylase deficiency is linked to mutations in the OTC gene located on the X chromosome, making it an X-linked disorder. This genetic aspect means that males are more frequently and severely affected due to having only one X chromosome. Understanding these genetic factors allows for targeted therapies and counseling for affected families, including prenatal testing and gene therapy approaches aimed at correcting or compensating for the enzyme's deficiencies.

Related terms

Urea Cycle: A series of chemical reactions in the liver that convert ammonia, a toxic byproduct of protein metabolism, into urea for excretion.

Citrulline: An amino acid produced during the urea cycle from the reaction between ornithine and carbamoyl phosphate.

Carbamoyl Phosphate: A compound that serves as a substrate in the urea cycle, formed from ammonia and bicarbonate.