Uploaded byDhiraj Trivedi
Class 8 metabolism of phenyl alanine
Phenylalanine and tyrosine are broken down through several metabolic pathways. Phenylalanine is converted to tyrosine by phenylalanine hydroxylase. Tyrosine is then used to produce melanin, catecholamines, and thyroid hormones. Inborn errors in these pathways can occur. Phenylketonuria results from a deficiency of phenylalanine hydroxylase, causing phenylalanine to accumulate. Other disorders include alkaptonuria, tyrosinemia types I and II, and albinism.
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Overview of phenylalanine and tyrosine metabolism; mentions catabolism, errors, and disorders like phenylketonuria.
Details on phenylketonuria, symptoms, biochemical effects, and the importance of dietary management.
Processes converting tyrosine to catecholamines (dopamine, norepinephrine, epinephrine) and their functions.
Conversion of tyrosine to melanin, related disorders like albinism, and synthesis details.
The role of tyrosine in thyroid hormone synthesis, process details, and disorders related to iodine deficiency.
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Class 8 metabolism of phenyl alanine
- 1. Metabolism of phenylalanine Describe in brief catabolism of phenyl alanine . Add a note on inborn errors of phenyl alanine metabolism. Dr. Dhiraj J. Trivedi
- 2. Metabolism of phenylalanineand tyrosine PHENYLALANINE TyrosineMelanins Dopamine Norepinephrine Thyroxine, T3 Epinephrine Protein Glucose Lipid
- 3. Phenylalanine to Tyrosine PhenylalanineTyrosine Phenylalanine hydroxylase O2 H2 O Dihydro Biopterin Dihydro Biopterin reductase NADPH + HNADP H4 Biopterin Phenyl ketouria 1
- 4. Phenyl ketouria – Accumulatesphenyl keto acids Phenylalanine Phenylpyruvate Phenyl lactate Tyrosine Phenyl acetate Transaminase NADH H+ NAD+ NAD+ NADH H+ CO2 Dehydrogenase Phenyl acetate glutamateGlutamine Phenylalanine hydroxylase
- 5. Catabolism of tyrosine Tyrosine P-Hydroxy phenyl Pyruvate Homogentisate Tyrosine Transaminase P hydroxyphenyl pyruvate dioxygenase Cu2+ α Keto Glutarate Glutamate Ascorbate Dihydroascorbate + CO2 + H2O Tyrosinemia type II Neonatal tyrosinemia
- 6. Catabolism of tyrosine 4-Maleyl acetoacetate Homogentisate Homogentisate Oxidase Fe+2 O2 Alkaptonuria Autosomal recessive disorder Occurrence : 1 in 25, 000 Deficiency : Homogentisate oxidase Homogentisate accumulate in tissue , blood Excreted in urine Homogentisate get auto-oxidised to quinones , which polymerise to impart black colour. D-- Black colour urine on keeping . Ferric chloride and Silver nitrate test positive T-- No treatment Ochronosis
- 7. What is ochronosis Homogentisateaccumulate in body fluid and slowly deposited in bone , connective tissue and other organs. This condition is called OCHRONOSIS Bone and connective tissue become black stained This is thought to be responsible for arthritis in males.
- 9. Catabolism of tyrosine Fumaryl acetoacetate 4-Maleyl acetoacetate Maleyl acetoacetate isomerase Tyrosinosis Fumarate Acetoacetate Fumaryl acetoacetate hydrolase H2 O GS – SG
- 10. Phenyl alanine andTyrosine are glucogenic and ketogenic Fumarate Acetoacetate Glucose Fat or lipidTCA
- 11.
- 12. Phenyl ketouria – Autosomalrecessive type , Common A A metabolic disorder Found 1 in 10,000 births Deficiency of Phenyl alanine hydroxylase enzyme Result --- Phenyl alanine not converted to Tyrosine
- 13. Phenylketouria – Accumulates phenylketo acids Phenylalanine Phenylpyruvate Phenyl lactate Tyrosine Phenyl acetate Transaminase NADH H+ NAD+ NAD+ NADH H+ CO2 Dehydrogenase Biopterin deficiency
- 14. Phenyl ketouria – Causes-- Accumulation of phenyl Pyruvate , phenyl lactate, Phenyl acetate and Phenyl acetate glutamate in blood . Leads to keto acidosis Urine contains Phenyl Pyruvate , phenyl lactate and Phenyl acetate Giving mousy odor to urine.
- 15. Phenyl ketouria – Biochemicalmanifestations -- Mental retardation, Low IQ , neurological symptoms . Seizures and tremors are characteristic findings failure of growth and failure to walk or talk Impaired synthesis of serotonin ( due to PKA) Defective myelin formation, and hypo melanin pigmentation symptoms due to toxic effect of phenyl alanine. Biopterin deficiency may lead to this disorder (3%)
- 16. Phenylketouria – Diagnosis by-- Ferric chloride test and guthrie test (Bacterial Bioassay) Treatment : -- Low phenyl alanine diet, Tyrosine becomes essential amino acid Serious patients serotonin and Dopa to restore catecholamine level
- 17.
- 18. Tyrosine to catecholamine •Epinephrine, • Nor epinephrine and • Dopamine are amine derivatives of catechol, • Collectively called as Catecholamines. Dihydroxylated phenyl ring is named as catechol OH OH
- 19. Tyrosine to catecholamine Tyrosineenters mitochondria of adrenal medula and CNS Where it is hydroxylated on 3rd position To form DOPA Enzyme is mono-oxygenase type Tyrosinemia Albinism Tyrosine 3,4-dihydroxy phenyl alanine DOPA Tyrosine hydroxylase O2 H2O H4 Biopterin Dihydro Biopterin NADH NAD Reductase
- 20. Tyrosine to catecholamine DOPApermeate out of mitochondria And under go decarboxylation in cytoplasm to form Dopamine. Active neurotransmitter 3,4-dihydroxy phenyl alanine DOPA Dopamine DOPA decarboxylase CO2B6 PO4
- 21. Tyrosine to catecholamine DopamineNor epinephrine Dopamine β-hydroxylase Dopamine is hydroxylated to Nor – epinephrine, It require Vit C. Ascorbate Dehydro ascorbate H2OO2 In adrenal medulla
- 22. Tyrosine to catecholamine Methylgroup is donated from SAM to Nor epinephrine Which forms epinephrine. Nor epinephrine Epinephrine Methyl transferase SAM SAHC In adrenal medulla
- 23. Tyrosine to Epinephrine Tyrosine 3,4-dihydroxyphenyl alanine DOPA Dopamine Nor epinephrine Epinephrine Tyrosine hydroxylase DOPA decarboxylase Methyl transferase O2 CO2 Dopamine Β-hydroxylase SAM SAHC Biopterin Ascorbic acid Adrenal medulla and CNS
- 24. Functions of catecholamine •Epinephrine and Nor epinephrine regulates CHO and lipid metabolism • Dopamine and Nor epinephrine serves as NTs • Low level of Nor epinephrine is cause of mood variation in menstrual cycle. • Impaired synthesis of Dopamine relates with Parkinson’s • Tyrosine is therapeutic in stress and depression.
- 25.
- 26. • Black pigmentpresent in skin, Hair, retina of eye. • Synthesized from Tyrosine • Synthesis takes place in melanoblast cells Tyrosine to melanin
- 27. Tyrosine 3,4-dihydroxy phenyl alanine DOPA Tyrosinase Cu+2 O2 H2O H4 Biopterin Dihydro Biopterin Tyrosineto melanin Albinism •Autosomal recessive disorder •Occurrence 1 in 20, 000 •Deficiency or lack of Tyrosinase •Is most common cause •Albino skin, sensitive to light •Photophobia
- 29. Tyrosine to melanin 3,4-dihydroxyphenyl alanine DOPA Tyrosinase Cu+2 O2 H2O H4 Biopterin Dihydro Biopterin Dopaquinone 5,6-dihydroxy indole 2- carboxylic acid Non enzymatic spontaneous 5,6-dihydroxy indole CO2 Melanin Polymerise
- 30. Tyrosine to Thyroxinand T3
- 31. • Amino acidrequired for hormone synthesis. • Tetra iodo thyronine (Thyroxine) and tri iodo thyronine (T3) synthesized in thyroid gland. • Also called as organification of Iodine • Step 1 is Oxidation of Iodide • Step 2 Iodination of Tyrosine • Step 3 Coupling reaction Tyrosine to Thyroxine and T3
- 32.
- 33. Goiter Deficiency of Iodineleads to condition called goiter
- 34. Disorder Enzyme defect PhenylKetouria (PKU) Phenyl alanine hydroxylase absent. Alkaptonuria Homogentisate oxidase low or absent. Tyrosinemia – I or tyrosinosis Maleyl Acetoacetate isomerase or Fumaryl Acetoacetate hydrolase absent. Tyrosinemia – II Hepatic Transaminase defective. Neonatal Tyrosinemia p-hydroxy phenyl pyruvate hydroxylase Hereditary Tyrosinemia p-hydroxy phenyl pyruvate oxidase. Albinism Tyrosinase (low or absent) hypo melanosis due to defect in melanocytes. Q: Write inborn errors of phenyl alanine and tyrosine metabolism.
- 35.