Erythrocyte Biochemistry Flashcards
Structure of Hb
Hb is a tetramer, made up of [2 alpha globulin subunits] and [2 beta globulin subunits]
Heme
Heme is a HYDROPHOBIC prosthetic group that binds O2. There is 1 heme/subunit in Hb. So 4 hemes total.
Heme is made up of protophoryin IX and Fe2+.
For O2 to bind to heme, Fe must be in the ___ state
2+
Fe2+ is called
ferrous
What is erythropoiesis?
Erythropoiesis is the creation of RBC
What is the process of erythropoiesis
- Stem cell (hemocytoblast)
- Committed cell (proerythroblast)
- It then undergoes a developmental pathway where
A. ribosomes are made
B. Hb is made
C. nucleus and a majority of organelles are ejected
because RBC do not have organelles and have already
made their Hb - Erythrocyte
In the formation of a RBC, a majority of the ____ is made before the nucleus is ejected
Hb
Embroyonic Hb
- Hb Gower 1
- Hb Gower 2
- Hb Portland
By 8 weeks of gestation, they’re destroyed
Fetal Hb
- Hb F (alpha2gamma2)
Adult Hb
- Hb A (alpha2beta2) –> 97%
2. Hb A2 (alpha2delta2)–> 3%
What chromosome are responsible for the creation of Hb?
Chromosome 16
Chromosome 11
Sickle cell anemia is caused by a change in?
In HbS. the AA at position #6 of B-globulin chain changes from Glu–> Val
What are researchers trying to do to tx Sickle Cell Anemia?
Researchers are trying to induce the expression of HbF using hydroxyurea.
However, it is chemically.
Heme is stabilized by _____
Histadine
There are 2 histadines
- Histidine F8
2. Histidine E7
Histidine F8
Histidine F8 is the proximal histidine.
It connects the heme to the Hb.
Histidine E7
Histidine E7 is the distal histidine.
O2 binds to the Fe that is located between heme and Histidine E7.
Myoglobin has a _____ curve
hyperbolic
Hemoglobin has a ____ curve
sigmoidal because it participates in positive cooperativity
hb switches between ____ and _____ affinity
high and low
Is the binding of 02 reversible?
Yeth
positive cooperativity in hb
the binding of 1 O2 molecule will facilitate the binding of another O2 molecule.
A conformational change in 1 globin subunit will induce a conformational change in another subunit. How does this happen? When O2 binds to Fe2+, it causes a 0.4A change, pulling down the proximal F8 histidine, which changes the interaction with the associated globin chain.
What happens when O2 binds to Fe2?
When O2 binds to Fe2,
It causes a 0.4A change, pulling down the proximal His F8. this changes the interaction with the associated globins to that O2 can better bind. POSITIVE COOPERATIVTY O
pO2 in lungs
98%