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- Porphyrin synthesis:
- A) Pyrrole ring
- B) Porphin ring
- C) protoporphyrin IX
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- Heme = protoporphyrin IX + Fe
- Clorophyll is the same structure + Mg
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Heme biosynthesis
- Heme is made in every cell
- 85% is made in erythroid cells
- There are 8 enzymatic reactions in the process
- Mutations in the enzymes that control these reactions lead to the disorders known as porphyria
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- Porphyrias
- -Green: Hepatic porphyrias-Red: Erythropoietic porphyrias
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- δALA - δ-aminolevulinic acid
- First step of heme synthesis: Rate limiting
- Two forms of ALA Synthase (ALAS)
- -ALAS2: erythroid-specific form
- -ALAS1: ubiquitous form responsible for the production of heme in the liver
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