Heme Metabolism Flashcards
What is heme important for
Major part of hemoglobin, also myoglobin, cytochromes, CYP450, peroxidases and NO synthesis
What is porforin
Heme without iron
What are prophyrias
Inherited defects in heme synthesis
Intermediates in heme synthesis
Pyrole a 4 carbon ring with a Nitrogen
Bilirubin (multiple pyrole’s together)
Porphyrin - bilirubin in a ring
Heme - porphyrin with fe in the middle
How do we make heme
Glycine and succinyl coa combine to form g-aminolevulinic acid (ALA) with the help of ALA synthase which then is changed to porphobilinogen with the help of ALA dehydrogenase and then that goes to protoporphyrin and then heme
Regulation of heme synthesis
ALAS is inhibited by end products (heme) - end product feedback inhibition
ALAD is Zn dependent
Signs of porphyria
Skin rash, photosensitive, abdomen pain, neuropsych symptoms, dark urine
Types of porphyria
Erythropoietic
Hepatic (acute or chronic)
What precipitates acute hepatic porphyria
Drugs (barbiturates, Etoh)
Stressors
Heme degradation
Heme is degraded to biliverdin them to bilirubin (which can cause jaundice)