Hemoglobin & Porphyrins
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Porphyrins are synthesized in the…
Liver and bone marrow.
What is the most common way to differentiate between porphyrins and porphyrinogens?
Porphyrins fluoresce red at 400 nm, while porphyrinogens do not.
What determines solubility in porphyrin and porphyrinogen?
Number of carboxyl groups.
Heme synthesis takes place in…
Nucleated red cells and early reticulocytes.
What enzyme is used for the following reaction?
ALA Synthase.
What enzyme is used for the following reaction?
ALA Dehydratase.
Describe a porphyrin ring.
4 pyrrole rings connected by methene bridges (double bond).
In heme synthesis, a deficiency in ALA dehydratase will cause what condition?
Plumboporphyria (PP).
In heme synthesis, a deficiency in PBG deaminase will cause what condition?
Acute intermittent porphyria (AIP).
In heme synthesis, a deficiency in Uroporphyrinogen III synthase will cause what condition?
Congenital Erythropoietic Porphyria (CEP).
In heme synthesis, a deficiency in Uroporphyrinogen decarbodylase will cause what condition?
Porphyria cutanea tarda (PCT); Hepatoerythropoietic porphyria (HEP).
What are the three types of hemoglobin?
Hemoglobin A, A2, and F.
ALA synthase and ALA dehydrase can be inhibited by ___.
Heme.
Ferrochelatase can be inhibited by ___ and ___.
heme; protoporphyrin IX.
Hemoglobin has a high ___ which allows it to readily pick up oxygen.
affinity.
What is the function of 2,3-bisphosphoglycerate (BPG) in the movement of oxygen and CO2?
Prevents oxygen from reattaching to heme groups.
Describe the oxygen dissociation curve (ODC).
Predicts the amount of saturated hemoglobin in regards to the amount of oxygen that is present.
What two factors affect hemoglobin’s affinity for oxygen?
pH and body temperature.
How will the following situation affect hemoglobin’s affinity to retain oxygen: ↑pH; ↑ affinity; ↓ temp; ↓DPG
Hemoglobin will retain oxygen.
How will the following situation affect hemoglobin’s affinity to retain oxygen: ↓pH; ↑temp; ↑DPG; ↓affinity
hemoglobin will readily release oxygen.
Lead poisoning causes an inhibition of which enzymes?
ALA dehydrase, coproporphyrinogen oxidase, and ferrochelatase.
Lead poisoning causes an elevated excretion of which enzymes?
ALA, urine coproporphyrin III, and erythrocyte protoporphyrin IX.
In neuropathy in lead poisoning increased ___ competes for binding sites for gamma amino butyric (neurotransmitter).
ALA.
Hoesch test is used to test for what?
Porphobilinogen.