Question

Which of these is not affected by tyrosine metabolism?
A. Calcitonin
B. Melanin
C. Thyroxine
D. Epinephrine

Answer 1

Tyrosine is a non-essential amino acid. It is produced in our body through phenylalanine. It is present in the milk protein. It is an important mood regulator.

Complete Answer:
- Tyrosine is 4-hydroxyphenylalanine. It is a hydrophobic amino acid. It is coded by the codon UAC and UAU. Mammal synthesis tyrosine from phenylalanine by the help of enzyme phenylalanine hydroxylase.

Metabolism Of tyrosine:
- Tyrosine residues are phosphorylated to produce phosphotyrosine. It is the key step in signal transduction.
- Tyrosine is converted to L-DOPA by enzyme tyrosine hydroxylase which is further converted to Dopamine. Dopamine is further converted to epinephrine also known as adrenaline and norepinephrine.
- Thyroid hormone thyroxine is also derived from tyrosine.
- Tyrosine is also the precursor to the pigment melanin. It is a pigment in our body which is responsible for the colour of hair skin and eyes.

- Calcitonin: It is a hormone which is secreted by the parafollicular cell of the thyroid gland. It regulates the calcium and phosphate level in blood.

Thus the correct answer is (A). Calcitonin is not produced by tyrosine metabolism.

Additional Information: Tyrosine is found in protein rich food such as chicken, turkey, milk, yogurt, cheese, peanuts, almonds etc.

Note: Tyrosine was first discovered by German chemist Justus von liebig in the protein casein from cheese. It is a proteinogenic amino acid. Tyrosine is metabolised in the cell by the process of phosphorylation, sulfation, and degradation to produce biologically important bio molecules which are important for the proper functioning of our body.