Myoglobin And Hemoglobin Flashcards
Cooperativity
Conformational changes in one subunit affects the others
How is heme bound to myoglobin and hemoglobin
Covalently
Heme prosthetic group structure
4 pyrope linked by methane bridges make porphyrin.
Porphyrin bound to Fe2+ makes protoporphyrin IX to heme
Oxygen binds distal His
Fe binds proximal His
T state
More interactions, more stable, lower O2 affinity
R state
Fewer interactions, more flexible, higher O2 affinity
Allosteric effects in hemoglobin
Increase H+= hemoglobin releases O2= 2,3 BPG binds + charge, stabilizing the T state
Metabolizing tissues
Release H+, lowering pH.
- H+ protonates Hb at His 146, which forms salt bridge with Asp 94
- Hb releases O2 here (Bohr effect)
This is why O2 is released to tissues when you work out
2,3 -BPG
- Stabilizes T state.
- Increased at high altitudes.
- binds w high affinity to hemoglobin which causes a conformational change resulting in release of oxygen
CO binding
Blocked by distal histidine bc wont allow CO to bind linearly to hemoglobin
Normal adult Hb
HbA a2B2
Sickle cell HbS
a2Bs2. glu to valine in B Globin gene. (Polar to non polar)
Favor T state (high BPG) low pH
Infant Hb (fetal) HbF
Alpha 2 gamma 2
Hemoglobin A2
Alpha 2 delta 2. Ab 2% of total hemoglobin.
Appears shortly after birth
HbA1c
Glycated HbA.
Alpha 2 beta 2-glucose.
Increased in diabetes mellitus
