Preliminary worning!
These lesson slides only provide an outline.
You must study miyglobin and hemoglobin using a Biochemistry textbook.
Myoglobin (Mb)
Hemoglobin (Hb)
Protein formed by 4 subunits each of them is similar to myoglobin.
EME and oxygen
Proxymal Histidine.
Myoglobin and Hemoglobin structure
- Differences in iron oxydation.
- Effect of amino acid moiety on Fe-CO affinity.
- Switch between taut “T” and relaxed “R” state.
Myoglobin saturation curve
Hemoglobin saturation curve
Hb affinity curve for different human populations. Fetal Hb affinity .
Modulators of Hb-O2 affinity
Stabilizers of T form favour the release of oxygen so the deoxy-Hb:
- 2,3 BPG;
- Low pH;
- Increase in CO2 (Bohr effect).
Physiological relevance of Bohr effect
In the tissue the increase in [CO2] leads to a pH decrease
CO2 +H2O → HCO3- + H+
At low pH ionic interaction between some amino acids is favoured (Es His 146 Asp 94) and the T form is stabilised.
CO2 directly binds the free amino group forming carbamate adducts stabilizing T form and contributing about 25% of CO2 overall transportation.
