Haem biosynthesis ppt BIOCHEMISTRY vkunder637@gmail.com

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  • Biosynthesis of porphobilinogen. ALA synthase occurs in the mitochondria,whereas ALA dehydratase is present in the cytosol.The substrates are succinyl-CoA and glycineThe product is delta-aminolevulinic acid (ALA).An essential cofactor is pyridoxal phosphate (vit B-6).This is the rate-limiting reaction of heme synthesis in alltissues, and it is therefore tightly regulated.
  • The substrates are two molecules of ALA.The product is porphobilinogen, the first pyrrole.ALA dehydratase is a -SH containing enzyme.• It is very susceptible to inhibition by lead.
  • Conversion of porphobilinogen to uroporphyrinogens.Uroporphyrinogen synthase I is alsocalled porphobilinogen (PBG) deaminase or hydroxymethylbilane(HMB) synthase.
  • Decarboxylates the acetic acid groups, converting them tomethyl groups.
  • Catalyzes the conversion of two propionic acid groups to vinylGroupsProtoporphyrinogen IX oxidase converts the methylenebridges between the pyrrole rings to methenyl bridges.Ferrochelatase adds Fe++ to protoporphyrin IX, formingheme.• The enzyme requires Fe++, ascorbic acid and cysteine(reducing agents).• Ferrochelatase is inhibited by lead.
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  • Haem biosynthesis ppt BIOCHEMISTRY vkunder637@gmail.com

    1. 1. Dr. Vijay Marakala, MBBS, MD. Assistant professor BIOCHEMISTRY SIMS & RC
    2. 2. Heme synthesis Heme degradation •Heme Metabolism
    3. 3. •Heme synthesis
    4. 4. Haemoglobin
    5. 5. Haem • Heme is a member of a family of compounds called porphyrins. • Many important proteins contain heme as a prosthetic group.
    6. 6. Porphyrins • Porphyrins are cyclic compounds composed of held together by methenyl bridges.
    7. 7. Porphyrins • Porphyrins are substituted at positions 1-8
    8. 8. •Porphyrins
    9. 9. •Porphyrins
    10. 10. •Haem synthesis
    11. 11. •Heme synthesis - site Tissues •Liver •Bone marrow Cell •Mitochondria •Cytoplasm
    12. 12. •Reactions of Heme synthesis ALA synthesis Formation of Porphobillinogen Formation of Hydroxymrthylbilane Formation of Uroporphyrinogen Synthesis of Coproporphyrinogen Synthesis of Protoporphyrinogen Generation of Protoporphyrin Generation of Heme
    13. 13. ALA SYNTHASE STEP 1
    14. 14. δ ALA DEHYDRATASE 2 δALA STEP 2
    15. 15. STEP 3
    16. 16. STEP 4
    17. 17. STEP 5
    18. 18. 3 4 5
    19. 19. STEP 6 STEP 8 STEP 7
    20. 20. Regulation of heme synthesis

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