HEME BIOSYNTHESIS EXAM QUESTIONS
AND ANSWES
How is heme metabolism connected to glycolysis ? Name the step in
glycolysis that is relevant
objective
During the step between
Glyceraldehyde-3-P -------> 1,3-Bisphosphoglycerate
NADH is produced in this step.
This NADH is used to reduce methemoglobin (Fe+3) -----> hemoglobin
Fe+3
NADH could also be used to convert pyruvate to lactate
What does methylhemoglobin blood look like?
Blood will be dark chocolate color
methylmeglobin =Fe+3
Read More
What is the rate limiting step of heme synth?
What are the cofactors?
What are the inhibitors and negative regulator?
objective
Succinyl-CoA + glycine ------δAminolevulinic acid synthase----> δ-
Aminolevulinic acid ( δ-ALA)
δAminolevulinic acid synthase requires: Vitamin B6 (pyridoxine)
Inhibited by: Heme and glucose
, ALAS1 vs ALAS2
which one is inhibited by heme ?
which one will be affected by sideroblastic anemia?
What kind of cells will you find each?
ALAS1 (liver/other tissues):
- regulatory heme (excess after target proteins are saturated)
• exerts multiple inhibitory effects
(transcription, translation, mitochondrial import)
- activated by drugs (e.g., phenobarbital)
- provides more heme for liver cytochrome P450s!!
ALAS2 (erythroid cells):
- iron regulatory protein (IRP)
• low iron; binds 5'-UTR of mRNA, translation inhibited
high ironIRP degraded, translation ensues
(provides iron-containing heme for hemoglobin!!)
- will be affected by sideroblastic anemia
What disease is associated with δ-Aminolevulinic acid synthase?
What would a blood smear show?
Lab findings?
What are is the treatment?
objective
AND ANSWES
How is heme metabolism connected to glycolysis ? Name the step in
glycolysis that is relevant
objective
During the step between
Glyceraldehyde-3-P -------> 1,3-Bisphosphoglycerate
NADH is produced in this step.
This NADH is used to reduce methemoglobin (Fe+3) -----> hemoglobin
Fe+3
NADH could also be used to convert pyruvate to lactate
What does methylhemoglobin blood look like?
Blood will be dark chocolate color
methylmeglobin =Fe+3
Read More
What is the rate limiting step of heme synth?
What are the cofactors?
What are the inhibitors and negative regulator?
objective
Succinyl-CoA + glycine ------δAminolevulinic acid synthase----> δ-
Aminolevulinic acid ( δ-ALA)
δAminolevulinic acid synthase requires: Vitamin B6 (pyridoxine)
Inhibited by: Heme and glucose
, ALAS1 vs ALAS2
which one is inhibited by heme ?
which one will be affected by sideroblastic anemia?
What kind of cells will you find each?
ALAS1 (liver/other tissues):
- regulatory heme (excess after target proteins are saturated)
• exerts multiple inhibitory effects
(transcription, translation, mitochondrial import)
- activated by drugs (e.g., phenobarbital)
- provides more heme for liver cytochrome P450s!!
ALAS2 (erythroid cells):
- iron regulatory protein (IRP)
• low iron; binds 5'-UTR of mRNA, translation inhibited
high ironIRP degraded, translation ensues
(provides iron-containing heme for hemoglobin!!)
- will be affected by sideroblastic anemia
What disease is associated with δ-Aminolevulinic acid synthase?
What would a blood smear show?
Lab findings?
What are is the treatment?
objective
