Hematopoietic System Biochemistry 1 Flashcards
(27 cards)
What substance, when bound to heme, weakens the oxygen/heme bond and causes release of oxygen?
2,3-bisphosphoglycerate (2,3-bpg)
Thiamine is also needed for what transketolase reaction?
The hexose monophosphate shunt. Thiamine is a cofactor needed for all transketolase reactions.
What role does the hexose monophosphate shunt play in erythrocytes?
It produces NADPH which keeps glutathione in a reduced state. Glutathione is essential for RBCs to protect themselves against free-radical mediated damage
Which enzyme is used along with the nadph to reduce glutathione in the erythrocyte?
Glutathione reductase
What can bind to hemoglobin?
O2, CO2 and CO, H+, 2,3-bisphosphoglycerate
What amino acid is needed to maintain the functionality and structure of the hemoglobin?
Histidine
What are the three functions of hemoglobin?
Transport oxygen
Transport carbon dioxide
Act as a blood buffer
What 2 substances are the starting materials for heme synthesis?
Succinyl-CoA and glycine
Succinyl-CoA and glycine are the starting materials for heme synthesis.
What do they form?
Delta aminolevulinic acid
What is the regulatory enzyme in heme synthesis?
Delta-aminolevulinic acid synthase (alas)
The formation of porphobilinogen from Delta aminolevulinic acid is catalyzed by what enzyme?
Delta-aminolevulinic dehydrogenase (alad)
What substance inhibits alad?
Lead
What mineral is incorporated into heme?
Iron
What mineral is incorporated into heme?
Where does this take place?
In the mitochondrion
Where in the body does heme synthesis take place?
In the bone marrow
Congenital deficiencies of certain enzymes in the heme synthesis can cause what?
Porphyrias
In what other substances is heme found?
Myoglobin, cytochromes
Where does catabolism of heme take place?
First the spleen, then the liver and finally the intestines. It also occurs in the bone marrow.
What breaks 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?
In the liver. Conjugating the bilirubin makes it water soluble.
How is bilirubin excreted?
In the bile
Bacteria in the gut convert some of the bilirubin into what substance?
Urobilinogen
