Metabolismo do HEME - Aula de Bioquímica - Ensino Superior

Heme metabolism involves the synthesis, function, degradation, and pathologies associated with this essential molecule. Heme is a component of hemeproteins, such as hemoglobin, myoglobin, and cytochromes, and is composed of a protoporphyrin IX core with ferrous iron (Fe²⁺) at its center. 1. Heme biosynthesis Occurs primarily in the liver and bone marrow. It begins with the condensation of glycine and succinyl-CoA, forming δ-aminolevulinic acid (ALA), catalyzed by ALA synthase (the rate-limiting step). Several steps occur in the cytosol and mitochondria, involving enzymes such as ALA dehydratase, uroporphyrinogen decarboxylase, and ferrochelatase. Synthesis is regulated by negative feedback from heme/hemin and can be induced by drugs. 2. Porphyrias These are genetic or acquired diseases caused by enzyme deficiencies in the heme synthesis pathway. They can be hepatic or erythropoietic, with neurovisceral or cutaneous manifestations (photosensitivity). Examples: acute intermittent porphyria, porphyria cutanea tarda, and erythropoietic protoporphyria. 3. Heme degradation This occurs in the macrophages of the mononuclear phagocytic system. Heme is converted to biliverdin, then to bilirubin, which is transported to the liver, conjugated with glucuronic acid, and excreted in bile. In the intestine, bilirubin is transformed into urobilinogen, stercobilin (feces), and urobilin (urine). 4. Jaundice This is the yellowing of the skin and mucous membranes due to the accumulation of bilirubin. It can be: Pre-hepatic (hemolytic) Hepatic (hepatocellular) Post-hepatic (obstructive) There is also neonatal jaundice, common in newborns due to immaturity of the bilirubin-conjugating enzyme. 👉 Support the channel with any amount 😊 PIX code: [email protected] 🎥 Understanding heme metabolism has never been so easy! From start to finish, everything explained clearly and with good humor. Let's learn? 💥 #HemeMetabolism #HemeGroupMetabolism