Metabolism of porphyrins: metabolism of bile pigments, biochemistry of jaundices .
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Transcript of Metabolism of porphyrins: metabolism of bile pigments, biochemistry of jaundices .
Metabolism of Metabolism of porphyrins: porphyrins:
metabolism of bile metabolism of bile pigments, pigments,
biochemistry of biochemistry of jaundicesjaundices..
JAUNDICES
NORMAL METABOLISM OF BILE PIGMENTS
CELLS OF RESIndirect bilirubin
NADP+
NADPH2
Biliverdin reductase
Biliverdin
Iron
Globin
Verdoglobin
NADP+
Hemoxi-genase
NADPH2
Hemoglobin ERYTHROCYTES
KIDNEYS
Stercobilinogen
URINE
Stercobilin
Indirect bilirubin 1,7-20,5 mkmol/l
albumin
albumin
Indirect bilirubin
UDP-glucoronil-transferase
Direct bilirubin 0.8-4.3 mkmol/l
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin di-glucoronid, 80 %
Dipyrols
-glucoro-nidase
Glucoronic acid
Direct bilirubin
BILE
INTESTINE
Mesobilirubin
Mesobilirubin (urobilinogen)
Stercobilinogen
Stercobilin
STOOL
METABOLISM OF BILE PIGMENTS IN HEMOLYTIC JAUNDICE
CELLS OF RES
Indirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
ERYTHROCYTES
KIDNEYS
INTESTINE
STOOL
Stool hypercholic
URINEUrine dark
Mesobilirubin
Mesobilinogen (urobilinogen)
Stercobilinogen
Stercobilin
Stercobilinogen
StercobilinUrobilin
METABOLISM OF BILE PIGMENTS IN HEPATIC JAUNDICE
CELLS OF RES
Indirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
ERYTHROCYTES
KIDNEYS
Urobilinogen INTESTINE
STOOL
Stool hypocholic
URINEUrine dark
Stercobi-linogen
StercobilinBilirubinUrobilin
Mesobilirubin
Mesobilinogen (urobilinogen)
Stercobilinogen
Stercobilin
METABOLISM OF BILE PIGMENTS IN OBSTRUCTIVE JAUNDICE
CELLS OF RESIndirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
Bile acids
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
Direct bilirubin
ERYTHROCYTES
KIDNEYS
Direct bilirubinINTESTINE
STOOL
Stool acholic, steatorhea
URINE Direct bilirubin Bile acids
Urine dark, foaming
• Formation of active form of vitamin D
• Formation of vitamin A from carotins
• Depo of cyanocobalamine and folic acid
• Depo of vitamin E• Phosphorilation of vitamins B,
formation of coenzyme forms
VITAMIN METABOLISM IN LIVER
DETOXIFICATION OF TOXIC DETOXIFICATION OF TOXIC SUBSTANCES IN LIVERSUBSTANCES IN LIVER
Phase I and phase II.
Phase I: hydrolysis, reduction, oxidation.
These reactions introduce functional group (—OH, —NH2, —SH, or —COOH) and usually result in a little increase of hydrophylic properties
Phase II includes: glucuronation, sulfation, acetylation, methylation, conjugation with glutathione, conjugation with aminoacids (glycin, taurin, glutamic acid)
Phase II results in the marked increase of hydrophylic properties of xenobiotic.
REACTION ENZYME LOCALIZATION
PHASE I
Hydrolysis
Reduction
Oxidation
EsterasePeptidase Epoxide hydrolase
Azo- and nitro-reduction Carbonyl reductionDisulfide reductionSulfoxide reduction
Alcohol dehydrogenaseAldehyde dehydrogenaseAldehyde oxidaseXanthine oxidaseMonoamine oxidaseDiamine oxidaseFlavin-monooxygenasesCytochrome P450
Microsomes, cytosol, lysosomes, blood lysosomes Microsomes, cytosol
Microflora, microsomes, cytosolCytosol, blood, microsomesCytosolCytosol
CytosolMitochondria, cytosolCytosolCytosolMitochondriaCytosolMicrosomesMicrosomes
PHASE II
Glucuronide conjugationSulfate conjugationGlutathione conjugationAmino acid conjugationAcetylationMethylation
MicrosomesCytosol, microsomesCytosolMitochondria, cytosolMitochondria, microsomesCytosol, microsomes, blood
General ways of xenobiotics biotransformation and their localization in cell
PHASE I
Hydrolysis
Esterases (carboxyesterases, cholinesterases, phosphatases) Peptidases
ReductionMetals and xenobiotics containing aldehyde, keto, disulfide, alkyn, azo, or nitro group are often reduced
Reducing agents:Reduced glutathione, FADH2, FMN,NADH NADPH.
OxidationAlcohol dehydrogenase
Aldehyde dehydrogenase
Oxidizes aldehydes to carbonic acids
Xanthine dehydrogenase-Xanthine oxidase
Monoaminooxidase
Oxidative deamination of amines (serotonin) and many xenobiotics
Hem containing protein.
Catalyzes monooxigenation of oxygen atom into substrate; another oxygen atom is reduced to water
Electrons are transferred from NADPH to cytochrome P450 through flavoprotein NADPH-cytochrome P450 reductase.
Cytochrom P450
The highest concentration – in endoplasmic reticulum of hepatocytes (microsomes).
SCHEME OF MONOOXYGENASE SYSTEM
SCHEME OF MONOOXYGENASE SYSTEM IN ENDOPLASMIC RETICULUM
The example of reaction that is catalyzed by cytochrome P450: hydroxylation of aliphatic carbon
The example of reaction that is catalyzed by cytochrome P450: hydroxylation of aromatic carbon
Examples of reactions catalyzed by cytochrome P450: heteroatom oxygenation
Examples of reactions catalyzed by cytochrome P450: oxidative group transfer
JAUNDICES
NORMAL METABOLISM OF BILE PIGMENTS
CELLS OF RESIndirect bilirubin
NADP+
NADPH2
Biliverdin reductase
Biliverdin
Iron
Globin
Verdoglobin
NADP+
Hemoxi-genase
NADPH2
Hemoglobin ERYTHROCYTES
KIDNEYS
Stercobilinogen
URINE
Stercobilin
Indirect bilirubin 1,7-20,5 mkmol/l
albumin
albumin
Indirect bilirubin
UDP-glucoronil-transferase
Direct bilirubin 0.8-4.3 mkmol/l
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin di-glucoronid, 80 %
Dipyrols
-glucoro-nidase
Glucoronic acid
Direct bilirubin
BILE
INTESTINE
Mesobilirubin
Mesobilirubin (urobilinogen)
Stercobilinogen
Stercobilin
STOOL
Bilirubin di-glucoronid
HEMOLYTIC (PREHEPATIC) JAUNDICE
Jaundice due to the excessive breakdown of red blood cells.
Causes: •sickle cell anemia, •malaria, •thalassemia, •autoimmune disorders,•massive hemorrhage
METABOLISM OF BILE PIGMENTS IN HEMOLYTIC JAUNDICE
CELLS OF RES
Indirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
ERYTHROCYTES
KIDNEYS
INTESTINE
STOOL
Stool hypercholic
URINEUrine dark
Mesobilirubin
Mesobilinogen (urobilinogen)
Stercobilinogen
Stercobilin
Stercobilinogen
StercobilinUrobilin
PARENCHYMAL (HEPATIC) JAUNDICE
occurs due to the liver disease and inability of liver to metabolize and remove bilirubin from the biliary systemCauses:•cirrhosis, •cancer, •viral hepatitis, •Gilbert’s syndrome, toxins or drugs, etc.
METABOLISM OF BILE PIGMENTS IN HEPATIC JAUNDICE
CELLS OF RES
Indirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
ERYTHROCYTES
KIDNEYS
Urobilinogen INTESTINE
STOOL
Stool hypocholic
URINEUrine dark
Stercobi-linogen
StercobilinBilirubinUrobilin
Mesobilirubin
Mesobilinogen (urobilinogen)
Stercobilinogen
Stercobilin
is caused by obstruction of bile flow from the liver
ОBSTRUCTIVE (POST-HEPATIC) JAUNDICE
Causes: •carcinoma in the bile duct or gall bladder, •presence of gallstones in the biliary system, •infection by parasites, •pancreatitis, etc.
METABOLISM OF BILE PIGMENTS IN OBSTRUCTIVE JAUNDICE
CELLS OF RESIndirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
Bile acids
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
Direct bilirubin
ERYTHROCYTES
KIDNEYS
Direct bilirubinINTESTINE
STOOL
Stool acholic, steatorhea
URINE Direct bilirubin Bile acids
Urine dark, foaming