Which amino acid undergoes hepatic deamination?
**Core Concept**
The process of hepatic deamination refers to the removal of an amino group from an amino acid, resulting in the production of ammonia and a corresponding keto acid. This process is primarily carried out by the enzyme glutaminase in the liver, which breaks down glutamine into glutamate and ammonia.
**Why the Correct Answer is Right**
Glutamine is the most abundant free amino acid in the body and serves as a nitrogen carrier. In the liver, glutaminase catalyzes the conversion of glutamine into glutamate and ammonia. This process is crucial for the disposal of excess nitrogen in the form of ammonia, which is then converted to urea through the urea cycle. The liver's ability to deaminate glutamine helps maintain nitrogen homeostasis and prevents the accumulation of toxic ammonia levels.
**Why Each Wrong Option is Incorrect**
* **Option A:** Glycine is an amino acid involved in various metabolic pathways, including the synthesis of creatine and glutathione. However, it is not primarily deaminated in the liver.
* **Option B:** Alanine is an amino acid that undergoes transamination in various tissues, but it is not typically deaminated in the liver.
* **Option C:** Aspartate is an amino acid that can be involved in various metabolic processes, including the urea cycle. However, it is not the primary amino acid deaminated in the liver.
**Clinical Pearl / High-Yield Fact**
Glutamine's role as a nitrogen carrier highlights its importance in maintaining nitrogen homeostasis. This is particularly relevant in conditions such as hepatic encephalopathy, where ammonia levels are elevated, and glutamine levels are often increased.
**Correct Answer:** C. Glutamine.