Individuals suffering from phenylketonuria lack an enzyme required for the conversion of

Options

A. tyrosine to phenylalanine
B. phenylalanine to tyrosine
C. phenylalanine to phenylpyruvic acid
D. phenylpyruvic acid to phenylalanine

Answer

To solve the question regarding phenylketonuria (PKU) and the enzyme that is lacking in this condition, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Phenylketonuria (PKU)**:
- PKU is a genetic disorder caused by a deficiency in a specific enzyme. It is classified as an inborn error of metabolism.

2. **Identifying the Amino Acids Involved**:
- The primary amino acid involved in PKU is phenylalanine. In normal metabolism, phenylalanine is converted into another amino acid called tyrosine.

3. **Determining the Enzyme Deficiency**:
- The enzyme that is deficient in individuals with PKU is phenylalanine hydroxylase. This enzyme is responsible for converting phenylalanine into tyrosine.

4. **Consequences of the Enzyme Deficiency**:
- Due to the lack of phenylalanine hydroxylase, phenylalanine accumulates in the body and is converted into phenylpyruvic acid and other metabolites, which can lead to serious health issues, including intellectual disability.

5. **Conclusion**:
- Therefore, individuals suffering from phenylketonuria lack the enzyme that converts phenylalanine to tyrosine.

### Final Answer:
Individuals suffering from phenylketonuria lack an enzyme required for the conversion of **phenylalanine to tyrosine**.

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