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Heme biosynthesis and it’s general overview

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Adarsha Neupane

Heme biosynthesis involves 7 major steps to produce heme from its precursors. The major sites of heme biosynthesis are the liver and bone marrow. Disorders of heme synthesis can cause porphyrias, a group of inborn errors of metabolism associated with abnormalities in heme biosynthesis. Porphyrias are broadly classified into hepatic porphyrias, which affect the liver, and erythropoietic porphyrias, which affect red blood cell production.

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HEME BIOSYNTHESIS AND IT’S GENERAL OVERVIEW PBL GROUP:A 4TH BATCH BMCTH (KU)
INTRODUCTION TO HEAMOGLOBIN HAEMOGLOBIN HEME + GLOBIN HEME-PROSTHETIC GROUP (NON-PROTEINOUS PART) GLOBIN-APOPROTIEN HAEMOGLOBIN IS TETRAMERIC ALLOSTERIC PROTEIN MADE UP OF FOUR POLYPEPTIDE CHAINS HAVING TWO Α CHAIN -141 AMINO ACIDS TWO Β CHAIN -146 AMINO ACIDS BOND: NON-COVALENT STRUCTURES
Heme biosynthesis and it’s general overview
OVERVIEW OF HEME HEME IS COMPLEX OF PROTOPORPHYRIN IX HAVING FOUR PYRROLE RING BRIDGE BY METHENYL GROUP WITH CENTRALLY PLACED FERROUS IRON. HAVING CO-ORDINATION NUMBER VI IRON IS HELD IN THE CENTER OF THE HEME BY FOUR CO- ORDINATED BONDS OF NITROGEN LINKAGE IN PORPHYRIN RING. ANOTHER TWO, ONE FOR HISTIDINE RESIDUE OF GLOBIN MOLECULE AND WHEREAS THE OTHER POSITION IS AVAILABLE TO BIND OXYGEN AND CARBONDIOXIDE AND SOMETIMES FOR
BIO SYNTHESIS OF HEME IT CONSISTS OF 7 MAJOR STEPS WITH FORMATION OF DIFFERENT INTERMEDIATE PRODUCT. MAJOR SITES OF HEME BIOSYNTHESIS ARE THE IMMATURE STEM CELLS OF LIVER AND ALSO IN ERYTHROCYTE PRODUCING CELLS IN BONE MARROW.
Heme biosynthesis and it’s general overview
1.ALA-DEHYDRATASE IS A ZINC CONTAINING ENZYME WHICH GETS INHIBITED BY LEAD. 2.DRUGS LIKE BARBITURATES INDUCE HEME SYNTHESIS. 3.STEP CATALYZED BY FERROCHELATASE OR HEME SYNTHASE IS ALSO INHIBITED BY LEAD 4.INH (ISONICOTINIC ACID) THAT DECREASES THE AVAILABILITY OF PYRIDOXAL PHOSPHATE WHICH ULTIMATELY AFFECT THE HEME SYNTHESIS. 5.HIGH CONCENTRATION OF CELLULAR GLUCOSE ALSO INHIBIT ALA SYNTHASE. 6.ALA SYNTHASE IS RATE LIMITING ENZYME.
DISORDER OF HEME SYNTHESIS 1 PORPHYRIAS  GROUP OF INBORN ERROR OF METABOLISM ASSOCIATED WITH BIOSYNTHESIS OF HEME CHARACTERIZED BY INCREASE IN PRODUCTION AND EXCRETION OF PORPHYRINS  PORPHYRIAS BROADLY CLASSIFIED AS A. HEPATIC PORPHYRIAS B. ERYTHROPOIETIC PORPHYRIAS
Table-1: Major findings in disorders of porphyria
Heme biosynthesis and it’s general overview

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Heme biosynthesis and it’s general overview

  • 1. HEME BIOSYNTHESIS AND IT’S GENERAL OVERVIEW PBL GROUP:A 4TH BATCH BMCTH (KU)
  • 2. INTRODUCTION TO HEAMOGLOBIN HAEMOGLOBIN HEME + GLOBIN HEME-PROSTHETIC GROUP (NON-PROTEINOUS PART) GLOBIN-APOPROTIEN HAEMOGLOBIN IS TETRAMERIC ALLOSTERIC PROTEIN MADE UP OF FOUR POLYPEPTIDE CHAINS HAVING TWO Α CHAIN -141 AMINO ACIDS TWO Β CHAIN -146 AMINO ACIDS BOND: NON-COVALENT STRUCTURES
  • 4. OVERVIEW OF HEME HEME IS COMPLEX OF PROTOPORPHYRIN IX HAVING FOUR PYRROLE RING BRIDGE BY METHENYL GROUP WITH CENTRALLY PLACED FERROUS IRON. HAVING CO-ORDINATION NUMBER VI IRON IS HELD IN THE CENTER OF THE HEME BY FOUR CO- ORDINATED BONDS OF NITROGEN LINKAGE IN PORPHYRIN RING. ANOTHER TWO, ONE FOR HISTIDINE RESIDUE OF GLOBIN MOLECULE AND WHEREAS THE OTHER POSITION IS AVAILABLE TO BIND OXYGEN AND CARBONDIOXIDE AND SOMETIMES FOR
  • 5. BIO SYNTHESIS OF HEME IT CONSISTS OF 7 MAJOR STEPS WITH FORMATION OF DIFFERENT INTERMEDIATE PRODUCT. MAJOR SITES OF HEME BIOSYNTHESIS ARE THE IMMATURE STEM CELLS OF LIVER AND ALSO IN ERYTHROCYTE PRODUCING CELLS IN BONE MARROW.
  • 7. 1.ALA-DEHYDRATASE IS A ZINC CONTAINING ENZYME WHICH GETS INHIBITED BY LEAD. 2.DRUGS LIKE BARBITURATES INDUCE HEME SYNTHESIS. 3.STEP CATALYZED BY FERROCHELATASE OR HEME SYNTHASE IS ALSO INHIBITED BY LEAD 4.INH (ISONICOTINIC ACID) THAT DECREASES THE AVAILABILITY OF PYRIDOXAL PHOSPHATE WHICH ULTIMATELY AFFECT THE HEME SYNTHESIS. 5.HIGH CONCENTRATION OF CELLULAR GLUCOSE ALSO INHIBIT ALA SYNTHASE. 6.ALA SYNTHASE IS RATE LIMITING ENZYME.
  • 8. DISORDER OF HEME SYNTHESIS 1 PORPHYRIAS  GROUP OF INBORN ERROR OF METABOLISM ASSOCIATED WITH BIOSYNTHESIS OF HEME CHARACTERIZED BY INCREASE IN PRODUCTION AND EXCRETION OF PORPHYRINS  PORPHYRIAS BROADLY CLASSIFIED AS A. HEPATIC PORPHYRIAS B. ERYTHROPOIETIC PORPHYRIAS
  • 9. Table-1: Major findings in disorders of porphyria