Argininosuccinic acid

Argininosuccinic acid is a compound that plays a crucial role in the urea cycle, a series of biochemical reactions in mammals. The urea cycle is responsible for removing excess ammonia from the body. Argininosuccinic acid is an intermediate in this cycle, formed by the reaction of citrulline and aspartate.

Structure and Properties

Argininosuccinic acid is a diamino acid, meaning it contains two amino groups. Its molecular formula is C10H18N4O6. It is a white, crystalline substance that is soluble in water.

Role in the Urea Cycle

In the urea cycle, argininosuccinic acid is synthesized from citrulline and aspartate in a reaction catalyzed by the enzyme argininosuccinate synthase. This reaction also requires adenosine triphosphate (ATP) and produces adenosine monophosphate (AMP) and pyrophosphate (PPi) as byproducts.

Following its synthesis, argininosuccinic acid is converted into arginine by the enzyme argininosuccinate lyase. This reaction releases fumarate, which can enter the citric acid cycle (also known as the Krebs cycle).

Clinical Significance

Deficiencies in the enzymes that catalyze the reactions involving argininosuccinic acid can lead to serious health conditions. For example, a deficiency in argininosuccinate synthase can cause citrullinemia, while a deficiency in argininosuccinate lyase can cause argininosuccinic aciduria. Both of these are rare genetic disorders that can lead to an accumulation of ammonia in the body, causing neurological problems and other symptoms.

See Also

• Urea cycle
• Citrullinemia
• Argininosuccinic aciduria