A i A id M t b liA i A id M t b liAmino Acids MetabolismAmino Acids Metabolism

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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T iT iT iT i•• TyrosineTyrosine•• TyrosineTyrosine

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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TyrosineTyrosine NH2TyrosineTyrosineCH2 CH COOH

NH2

• It is α-amino, β-hydroxphenyl propionicStructureStructure

OHIt is α amino, β hydroxphenyl propionic

Nutrional ValueNutrional ValueOH

• It is nonnon--essentialessential amino acid

Metabolic FateMetabolic Fate• It is bothboth glucogenic and ketogenicMetabolic FateMetabolic Fate

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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TyrosineTyrosine

BiosynthesisBiosynthesis1. From phenylalanine

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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TyrosineTyrosine

1 Incorporated in protein structure

Metabolic FateMetabolic Fate1. Incorporated in protein structure2. Phosphoproteins 3 Biosynthesis of thyroid hormones3. Biosynthesis of thyroid hormones4. Biosynthesis of catecholamines5 Bi s th sis f l i i t 5. Biosynthesis of melanin pigment 6. Catabolised to fumarate and acetoacetate7 S th i f l7. Synthesis of glucose8. Synthesis of ketone bodies9 P t f ti9. Putrefaction

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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TyrosineTyrosineBiosynthesis of thyroid hormonesBiosynthesis of thyroid hormonesBiosynthesis of thyroid hormonesBiosynthesis of thyroid hormones

NH2CH CH COOH

NH2CH CH COOH

NH2

CH2 CH COOH CH2 CH COOH CH2 CH COOH

OH OHI

OHI I

II

Tyrosine Monoiodotyrosine Diiodotyrosine

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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TyrosineTyrosineBiosynthesis of thyroid hormonesBiosynthesis of thyroid hormones CH2 CH COOH

NH2

Biosynthesis of thyroid hormonesBiosynthesis of thyroid hormones

CH2 CH COOHNH2

CH2 CH COOHNH2

2

OI I

d l2

I OHI I

O

INH2

+Oxidative coupling

OHI OH

OHI

NH2

CH3 CH COOH

Monoiodotyrosine Diiodotyrosine Triiodothyronine (T3)Alanine

CH2 CH COOHNH2

CH2 CH COOHNH2

CH2 CH COOHNH2

Oxidative coupling

OI I

OHI I

OHI I

CH3 CH COOHNH2

+Oxidative coupling

OHI I

CH3 CH COOH

Diiodotyrosine Diiodotyrosine

Tetraiodothyronine (T4)Alanine

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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TyrosineTyrosineBiosynthesis of catecholaminesBiosynthesis of catecholaminesBiosynthesis of catecholaminesBiosynthesis of catecholamines

CH2 CH COOHNH2

CH2 CH COOHNH2 CH2 CH2 NH2

DOPA DOPA TyrosineTyrosine

OH OHHO

OHHO

DecarboxylaseDecarboxylaseTyrosineTyrosine

hydroxylasehydroxylase PLPCO2OH

TyrosineDihydroxy phenylalanine

DOPADopamineDopamine

CO2

Dopamine Dopamine ββ hydroxylasehydroxylase

½ O2

OHOH

Vit Cββ hydroxylasehydroxylase

CH CH2 NH2CH CH2 NH CH3

OHHO

OHHO NoradrenalineNoradrenaline

AdrenalineAdrenaline CH3

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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TyrosineTyrosineBiosynthesis of melanin pigmentBiosynthesis of melanin pigmentBiosynthesis of melanin pigmentBiosynthesis of melanin pigment

CH2 CH COOHNH2

CH2 CH COOHNH2

CH CH COOHNH2

CH2 CH COOH CH2 CH COOH

HO

CH2 CH COOH

O

Tyrosine Tyrosine hydroxylasehydroxylase

TyrosinaseTyrosinase

OH OH OO

T i

Dihydroxy phenylalanineDOPA

Dopaquinone

Tyrosine DOPA

DopachromeDopachrome

Melanin pigment

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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TyrosineTyrosineNH2

PutrefactionPutrefaction CH2 CH2 COOHCH2 CH COOH

2

P hydroxyphenyl

OHOH

P hydroxyphenylpropionicDecarboxylationDecarboxylation

CH2 COOHCH2 CH2 NH2

Tyrosine

P hydroxyphenyl

OHOH

yd o yp e yacetic

CH3 NH2

CH3

Tyramine

OHOH

P cresolPhenolPhenol

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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OH

TyrosineTyrosineTyrosine catabolismTyrosine catabolismTyrosine catabolismTyrosine catabolism

CH2 CH COOHNH2 OH

CH2 COOH

Homogentisic acidCH2 C COOH

O

TransaminaseTransaminase HydroxylaseHydroxylase

OHOH

OH

P hydroxyphenyl pyruvicHomogentisic oxidaseHomogentisic oxidase

α KG Glu ½ O2 CO2

VitC½ O2

PLP

CCOOHHC CH2 COOH

O

P hydroxyphenyl pyruvicMalyl acetoacetateTyrosine

CH2

HC

HCCO

II

CHOOC CH CH2 COOHO

O

IsomeraseIsomeraseFumaryl acetoacetateFumaryl acetoacetate

hydrolasehydrolaseCH2HC

CO

CH3 C CH2 COOH CHCH COOH

HOOC

Fumaryl acetoacetateAcetoacetate Fumarate

+H2O

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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Fumaryl acetoacetate

Tyrosine MatabolismTyrosine Matabolism Phenylalanine

Ph l l i h d lPh l l i h d lPhenylketonuriaPhenylketonuriaTyrosine

TransaminaseTransaminase

Phenylalanine hydroylasePhenylalanine hydroylase

Thyroid hormonesIodinationIodinationOxidative couplingOxidative coupling

PhenylketonuriaPhenylketonuria

Tyrosinaemia type IITyrosinaemia type II

P hydroxyphenyl pyruvicP hydroxyphenyl pyruvic P hydroxyphenyl pyruvic

hydroxylasehydroxylaseDOPA

Tyrosine hydroxylaseTyrosine hydroxylase

Neonatal tyrosinaemiaNeonatal tyrosinaemia AlbinismAlbinism

Homogentisic acid

hydroxylasehydroxylase

Homogentisic oxidaseHomogentisic oxidaseDopamine

DOPA quinoneDecarboxylaseDecarboxylaseNeonatal tyrosinaemiaNeonatal tyrosinaemia

AlkaptonuriaAlkaptonuriaMalyl acetoacetate

IsomeraseIsomerase

Dopamine

Noradrenaline

DopachromeHydroxylaseHydroxylase

AlkaptonuriaAlkaptonuria

Fumaryl acetoacetate

Fumaryl acetoacetateFumaryl acetoacetatehydrolasehydrolase

Noradrenaline

MelanineTransmethylaseTransmethylase

Tyrosinaemia type ITyrosinaemia type I

AcetoacetateFumarate +

hydrolasehydrolaseAdrenaline

Tyrosinaemia type ITyrosinaemia type I

Prof Dr Mohammad Ibrahim Prof of Medical Biochemistry http://osp.mans.edu.eg/medbiochem_mi

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