Which enzyme is used to convert phenylalanine to tyrosine:
**Core Concept**
The conversion of phenylalanine to tyrosine is an essential biochemical reaction that occurs in the liver. This process is mediated by a specific enzyme that plays a crucial role in the biosynthesis of tyrosine, a non-essential amino acid.
**Why the Correct Answer is Right**
The correct enzyme responsible for converting phenylalanine to tyrosine is phenylalanine hydroxylase (PAH). This enzyme catalyzes the hydroxylation of phenylalanine to form tyrosine, using tetrahydrobiopterin (BH4) as a cofactor. PAH is encoded by the PAH gene and is expressed primarily in the liver. The reaction is essential for the synthesis of tyrosine, which is then used for protein synthesis, neurotransmitter production, and other vital functions.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the correct enzyme involved in the conversion of phenylalanine to tyrosine.
* **Option B:** This option is incorrect because it is not a relevant enzyme in the context of phenylalanine and tyrosine metabolism.
* **Option C:** This option is incorrect because it is not the correct enzyme responsible for the conversion of phenylalanine to tyrosine.
**Clinical Pearl / High-Yield Fact**
Deficiencies in phenylalanine hydroxylase (PAH) can lead to phenylketonuria (PKU), a genetic disorder characterized by elevated levels of phenylalanine in the blood, which can cause intellectual disability and other neurological problems if left untreated.
**Correct Answer: C. Phenylalanine hydroxylase**