Metabolisme Heme dan Globin dr. Erdiana
Hemoglobin terdiri dari heme (porfirin yang mengikat zat besi) dan ferroporfirin rantai polipeptida globin (alfa,beta,gama, dan delta
Struktur Hemoglobin 4 molekul protein 4 heme HbA (2 alpha-globulin chains dan 2 beta-globulin chains) HbF (2 alpha & 2 gamma) HbA2 (2 alpha & 2 delta)
141 molekul asama amino pada rantai alfa 146 mol asam amino pada rantai beta, gama dan delta
Heme Synthesis Heme is synthesized in a complex series of steps involving enzymes in the mitochondrion and in the cytosol of the cell The first step in heme synthesis takes place in the mitochondrion, with the condensation of succinyl CoA and glycine by ALA synthase to form 5-aminolevulic acid (ALA)
This molecule is transported to the cytosol where a series of reactions produce a ring structure called coproporphyrinogen III This molecule returns to the mitochondrion where an addition reaction produces protoporhyrin IX The enzyme ferrochelatase inserts iron into the ring structure of protoporphyrin IX to produce heme
Heme Biosynthesis. The sythesis of heme is a complex process that involves multiple enzymatic steps. The process begins in the mitochondrion with the condensation of succinyl-CoA and glycine to form 5-aminolevulinic acid. A series of steps in the cytoplasm produce coproporphrynogen III, which re-enters the mitochondrion. The final enzymatic steps produce heme.
Globin Synthesis Two distinct globin chains (each with its individual heme molecule) combine to form hemoglobin One of the chains is designated alpha. The second chain is called "non-alpha".
2 Suksinil-KoA + 2 Glisin membentuk senyawa Pirol 4 Pirol akan membentuk senyawa Protoporfirin IX Protoporfirin IX + Fe2+ membentuk senyawa Heme 4 Hem + Polipeptida membentuk Rantai Hemoglobin (α atau β) Rantai 2α + Rantai 2β membentuk hemoglobin A
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