Phenylalanine and tyrosine are twin amino acids where phenylalanine is essential and tyrosine is non-essential. Phenylalanine must be converted to tyrosine to perform its functions. This conversion is done through an irreversible reaction where an enzyme adds a hydroxyl group to phenylalanine. Tyrosine can then go through anabolic or catabolic pathways. The anabolic pathway produces catecholamines, melanin, and thyroxine, while the catabolic pathway breaks down tyrosine. Genetic defects in enzymes in these pathways can cause metabolic disorders like phenylketonuria, alkaptonuria, and tyrosinemia type 2.

1. Phenylalanine and
Tyrosine
Submitted to:- Dr. Sajad Ahmed Bhat
Submitted by:- Laxmi Chahar and Kumud Chauhan
Group number:- 04

2. Introduction:-
PHENYLALANINE V/S TYROSINE:-
• Essential Non-essential
• Non-polar Non- Polar
• Ketogenic and glucogenic ketogenic and glucogenic
Amino acid amino acid

3. • Both phenylalanine and tyrosine are twin amino acid...
Phenylalanine can’t do it’s function alone it have to be
convert into tyrosine.

5. Metabolism of phenylalanine and tyrosine:-
• Firstly conversion of phenylalanine to tyrosine:-

6. •An hydroxy group is added to phenylalanine then it
is converted to tyrosine.
•This reaction is completely irreversible reaction.
•Here phenylalanine hydroxylase is monooxygenase.
•After conversion into tyrosine, this tyrosine can
further go to anabolic and catabolic pathway.

7. Catabolic pathway of tyrosine

10. Anabolic pathway of tyrosine:-
• It convert into-
• Catecholamines
• Melanin
• Thyroxine

11. Metabolism of
Catecholamines:-

12. • 2. Melanin:- This melanin is synthesized in melanosomes in
melanocytes.
• 3. Thyroxine:- synthesized in the thyroglobulin present in thyroid
follicles.

13. Metabolic disorders:-
(A)Phenylketonuria:-
Enzyme defect is Phenylalanine hydroxylase
phenylalanine cannot convert into tyrosine. Bcz of enzyme deficiency it
convert phenylpyruvate which by oxidation convert into phenylacetate
and by reduction convert to phenyl lactate.
This phenyacetate is responsible for mousy body odour.
Due to unable to make tyrosine it there is decrement of melanin,
catecholamines and Tyrosine.

14. Clinical features-
• Blue eyes
• Fair skin
• Mousy odour
• Mental retardation
• Agitation
• Blonde hair.
• Seizures

17. •(B) Alkaptonuria:-
Enzyme defect in homogentisate oxidase due to
which Homogentisate can’t convert into Malyl acetic
acid in place it form alkaptone bodies.
There is deposition of homogentisate occur.
Alkaptone bodies mainly accumulated in
cartilagenous tissue like sclera, nose etc.

18. Clinical features:-
• No mental retardation
• Darkening of urine
• Black spots due to deposition
of Alkaptone bodies.

19. • (C) Tyrosinemia-
Tyrosinemia type-2
This disorder is also known as Richner- Hanhart Syndrome.
It is due to defect in the enzyme tyrosine transaminase.
This disease is characterized by:-
• Skin lesions
• Eye lesions
• Mental retardation

21. • Lack of melanin in albinos makes them sensitive to
sunlight.
• Increased susceptibility to skin cancer (carcinoma).
• Photophobia (intolerance to light) is associated with lack
of pigment in the eyes
• However, there is no impairment in the eyesight of
albinos.
• Their entire body, including their hair, is characteristically
white.

22. Thank you🙏