Ornithine transcarbamylase

Ornithine transcarbamylase (OTC) is an enzyme that plays a crucial role in the urea cycle, a process that is responsible for the detoxification of ammonia in the body. OTC is the second enzyme in the urea cycle and catalyzes the reaction between carbamoyl phosphate and ornithine to form citrulline and phosphate.

Structure

OTC is a trimeric enzyme located in the mitochondria. Each subunit of the enzyme is composed of approximately 300 amino acids. The active site of the enzyme, where the reaction takes place, is located in the cleft between two domains of the enzyme.

Function

The primary function of OTC is to catalyze the reaction between carbamoyl phosphate and ornithine to form citrulline and phosphate. This reaction is a key step in the urea cycle, which is the primary pathway for the removal of toxic ammonia from the body.

Clinical significance

Deficiency in OTC is the most common cause of urea cycle disorders. This deficiency can lead to an accumulation of ammonia in the body, which can cause a variety of symptoms including vomiting, lethargy, and in severe cases, coma or death. Treatment for OTC deficiency typically involves a low-protein diet and medications to help remove ammonia from the body.

See also

• Urea cycle
• Enzyme
• Ammonia
• Mitochondria