Biochemistry- Hemoglobins Flashcards
What substance, when bound to heme, weakens the oxygen/heme bond causing the oxygen to be released?
2,3- diphosphoglycerate
What can bind to hemoglobin?
O2, CO2, CO, H+, and 2,3- diphosphoglycerate
What are the 3 functions of hemoglobin?
oxygen transport, CO2 transport, blood buffer
What 2 substances are the starting material for heme synthesis?
succinyl CoA, glycine
What do succinyl CoA and glycine form?
delta aminolevulenic acid (and then –> heme formation)
What is the regulatory enzyme in heme synthesis?
Delta aminolevulenic acid synthase (ALAS)
The formation of porphobilinogen from Delta aminolevulenic acid is catalyzed by what enzyme?
Delta aminolevulenic dehydrogenase (ALAD)
What substance inhibits ALAD?
Lead
What mineral is incorporated into heme?
Iron
Where does heme synthesis take place?
mitochondria
Where in the body does heme synthesis take place?
bone marrow
Congenital deficiencies of certain enzymes in the heme synthesis are known as:
porphyrias
In what other substances is heme found?
Myoglobin, cytochromes
Where does catabolism of heme take place?
Spleen, then liver and finally intestines. may also occur in bone marrow
What creaks down heme during tissue damage?
macrophages
what is the first substance produced by heme catabolism?
biliverdin
Biliverdin is converted into what molecule?
bilirubin
Where is bilirubin conjugated?
liver
How is bilirubin secreted?
in bile
Bacteria in the gut convert some of the bilirubin into what substance?
Urobilinogen
What is the fate of urobilinogen?
reabsorbed, transported to the kidneys and converted into urobilin and excreted
What are the 2 excretory pathways for heme catabolism?
feces and urine
What role does H+ binding to hemoglobin have?
induces hemoglobin to unload its bound oxygen
