Heme Synthesis Flashcards
Name the heme proteins
hemoglobin, myoglobin, cytochrome, catalase, tryptophan pyrrolase
What are porphyrins
Intermediates during heme synthesis
What joins pyrrole rings together
methenyl
Which atom in the pyrrole ring attaches to metal ion
Nitrogen
Porphyrin Intermediates during heme synthesis
Uroporphyrin, Coporphyrin and Protoporphyrin
Side chains of uroporphyrin
4 acetyl and 4 proprionyl
Side chains of coporphyrin
4 methyl and 4 proprionyl
Side chains of protoporphyrin
4 methyl, 2 vinyl and 2 propionyl
Uroporphyrin is excreted in urine or feces?
Urine
Coporphyrin and Protoporphyrin is excreted in urine/feces?
Feces
Which type (I or III) of uroporphyrin is important in humans
Type III
Which type of cells cannot synthesize heme
Red blood cells
What is the rate limiting enzyme of heme synthesis in the liver
delta- aminolevulinic acid synthase
What is the enzyme delta- aminolevulinic acid synthase inhibited by
Heme
In heme synthesis, which reaction requires pyridoxal phosphate (vitamin B6)
Conversion of glycine and succinyl coA to delta- aminolevulinic acid synthase
Which two reactions in heme synthesis are inhibited by heavy metal poisoning (eg. lead)
- Conversion of delta- aminolevulinic acid synthase to porphobilinogen
- Conversion of protoporphyrin IX to Heme
Which two enzymes in heme synthesis are inhibited by heavy metal poisoning (eg. lead)
- Aminolevulinic acid
dehydratase - Ferrochelatase
What are porphyrias
Accumulation of porphyrin-like precursors due to disruption in heme synthese
How will the urine appear in individuals wit porphyrias
Red urine
What is the name of the type of porphyrias caused by heavy metal (lead) poisoning
Acquired porphyrias
Which type of porphyria is the most common
Porphyria cutanea tarda
Which type of porphyria occurs when there is a disruption of the synthesis hydroxymethylbilane from porphobilinogen
Acute Intermittent Porphyria
Which porphyria is associated with photosensitivity
Porphyria cutanea tarda
Which porphyria, in severe cases, is associated with dark wine colored urine if it is left to stand
Acute intermittent porphyria
Which two metabolic pathways require Vitamin B6 (pyridoxal phosphate)
Transamination during amino acid metabolism and during heme synthesis
