1. A m I n o c d S M E T B O L
Tyrosine
Tyrosine is a non essential Amino Acid synthesized from hydroxylation of phenylalanine by the phenylalanine hydroxylase
Tyrosine
phenylalanine

2. Metabolism of Tyrosine was divided into 2 parts:c d S M E T B O L
Metabolism of Tyrosine was divided into 2 parts:
1. Transamination Pathway.
2. Synthesis of specialized products.
A- Thyroid Hormones T3. T4.
B- Adrenalin & nor adrenalin.
C-Melanin pigment of the skin

3. Transamination of Tyrosinec d S M E T B O L
Transamination of Tyrosine
parahydroxyphenylpyruvate hydroxylase
oxidase
Schematic presentation of Tyrosine Metabolism

4. m I n o c d S M E T B O L A The end result of tyrosine metabolism are
1.Fumarate …………. Citric Acid cycle
2.Acetoacetate& Acetate……………..Fatty Acid Synthesis
Tyrosine is both glucogenic & Ketogenic
Fumarate Glucogenic
Acetoacetate Ketogenic

5. Inborn Error diseases of Tyrosine (Metabolic disorders)
Type 2 Tyrosinemia
Neonatal Tyrosinemia
Alkapotoneuria
Type 1 Tyrosinemia

6. #Deficiency of tyrosine transaminase. B O L
Type 2 Tyrosinemia
#Deficiency of tyrosine transaminase.
# mild to severe keratitis.erosive lesion of the palm,,
# Skin lesions, hyperkeratosis of the palm and the hand.
#Mental retardation.
# High level of tyrosine in the blood.
# harmful untreatable disease.

7. #Deficiency of parahydroxyphenyl pyruvate hydroxylase.m I n o c d S M E T B O L
Neonatal Tyrosinemia
#Deficiency of parahydroxyphenyl pyruvate hydroxylase.
# Accumulation of parahydroxyphenyl pyruvic acid (Toxic).
# Hepatosplenomegally.
#Harmful untreatable Death before the age of 6 months

8. #Deficiency of homogentisic acid oxidase. B O L
Alkaptonuria
# Autosomal recessive.
#Deficiency of homogentisic acid oxidase.
#Increase homogentisic acid in blood and urine.
#Homogentisic acid on standing become black pigment. .(Alkapotonuria)
#It may be precipitate in the cartilage specially in the ear.
#Harmless.
#Diagnosis: Black color urine.
#Ferric chloride test is positive.

9. A m I n o c d S M E T B O L

10. Type1 Tyrosinemia (Tyrosinosis) c d S M E T B O L
Type1 Tyrosinemia (Tyrosinosis)
# Acute form lead to vomiting&diarrhoea.
#Failure to thrive.
#Deficiency of Fumaryl acetate hydroxylase.
#Mostly die before age of 6-8 months (Acute form).
#Death due to liver failure.
#Chronic form similar but milder ,death usually before age of 10 Years.
#Example of harmful untreatable diseases.

11. Metabolism of tyrosine in melanocyte(skin)d S M E T B O L
Metabolism of tyrosine in melanocyte(skin)
Schematic presentation of Tyrosine metabolism in the skin

12. Metabolism of Tyrosine in the melanocyte(Skin)d S M E T B O L
Metabolism of Tyrosine in the melanocyte(Skin)
1.Hydroxylation of tyrosine by tyrosinase enzyme to form dihydroxyphenylalanine(L-Dopa).
2. Dihydroxyphenylalanine is converted to Dopaquinone.
3.Dopaquinone is converted to melanin pigment.
4. L-Dopa is decarboxylated in the brain to form Dopamine.( epinephrine and nor epinephrine.)
5.Dopamine is deficient in brain patient with parkinsonism.
6.Minor pathway is that tyrosine is decarboxylated to form tyramine a vasopressor agent.

13. Inborn Error (Metabolic disease)of Tyrosine in the skin.
Albinism.
# Deficiency of tyrosinase enzyme of melanocytes.
#Failure of melanocyte to form melanin pigments.
#Whitish skin, Whitish eye lashes, whitish hair
#Intolerance to sunlight.
#Harmless condition.

14. A m I n o c d S M E T B O L
Parkinson disease is linked with decrease production of dopamine .The disease is due to degeneration of certain part of the brain leading to impairment synthesis of dopamine.
Treatment: dopamine can not enter the brain hence its administration is of no use.
L- dopa or levodopa is used in the treatment of Parkinson . In the brain DOPA is decarboxylated to dopamine which alleviates the symptoms but dopamine synthesis occurs in various tissue causing side effect, such as nausea, vomiting hypertension
Sinemet contain L=Dopa 250mg and carbidopa 25mg act as peripheral decarboxylase inhibitor to prevent decarboxylation in various tissue and decrease the side effect

15. m I n o c d S M E T B O L Melanin Tissue Proteins Diet Phenylalanine
Tyrosine
DOPA
PAH
phenyl-
pyruvic acid DA
(dopamine)
p-hydroxy-
phenlypyruvate NE
(norepinephrine)
homogentisic
acid
thyroxine
The main metabolic pathways of phenylalanine and tyrosine in the human

16. m I n o c d S M E T B O L Melanin Tissue Proteins Diet Albinism
Phenylalanine
Tyrosine
DOPA
p-hydroxy-
phenlypyruvate
homogentisic
acid
thyroxine
Alkaptonuria
goitrous
cretinism
Tyrosinosis
PKU
phenyl-
pyruvic acid DA
(dopamine) NE
(norepinephrine)
Schematic presentation of main inborn error of metabolism of Tyrosine