high for myoglobin and low for hemoglobin
Oxygen Binding Comparison: Myoglobin vs Hemoglobin
This question assesses the difference in oxygen ($O_2$) binding extent between hemoglobin and myoglobin at pH 7.2 and a partial pressure of oxygen ($P_{O_2}$) of 10 Torr.
Myoglobin's High Oxygen Affinity
Myoglobin is adapted for oxygen storage in muscles. It possesses a very high affinity for oxygen, characterized by a low P50 value (the $P_{O_2}$ needed to reach 50% saturation), typically around 1-2 Torr.
- At a $P_{O_2}$ of 10 Torr, myoglobin is significantly saturated with oxygen.
- Consequently, the extent of $O_2$ binding for myoglobin is high under these conditions.
Hemoglobin's Lower Oxygen Affinity
Hemoglobin transports oxygen in the blood and exhibits lower affinity compared to myoglobin, especially under conditions favoring oxygen release. Its oxygen binding curve is sigmoidal.
- Hemoglobin's P50 is considerably higher than myoglobin's, usually around 26-30 Torr at pH 7.4.
- A pH of 7.2 slightly decreases hemoglobin's affinity for oxygen (Bohr effect), further reducing saturation at a given $P_{O_2}$.
- At 10 Torr $P_{O_2}$, which is far below its P50, hemoglobin saturation is relatively low.
- Therefore, the extent of $O_2$ binding for hemoglobin is considered low at pH 7.2 and 10 Torr $P_{O_2}$.
Summary of Oxygen Binding Extent
Based on the distinct affinities:
- Myoglobin shows high $O_2$ binding at 10 Torr $P_{O_2}$.
- Hemoglobin shows low $O_2$ binding at 10 Torr $P_{O_2}$ and pH 7.2.
This difference is crucial for hemoglobin's function in oxygen delivery to tissues where myoglobin resides.
Important Questions from Bioinorganic Chemistry
Consider the following transformation reactions in the context of co - enzyme B12
A. 1, 2 - Carbon shift
B. Hydration of CO2
C. Benzene to phenol
D. Dimethyl sulfide to dimethyl sulfoxide
The correct statement(s) for co - enzyme B12 is / are
During the binding of O2 to myoglobin (consider 'heme' in xy-plane), the molecular orbital of O2 and atomic orbital of Fe involved in the formation of the σ-bond is
In the catalytic cycle of Cytochrome P450, the generation of [(porphyrin)+•FeIV(O)] from [(porphyrin)FeIII(OOH)] involves
Match List I with List II
List I
List II
Metalloprotein
Metal
A.
carboxypeptidase A
I.
Mn
B.
oxygen-evolving complex
II.
Fe
C.
hemerythrin
III.
Ni
D.
coenzyme F-430
IV.
Zn
Choose the correct answer from the options given below:
In solution, Vaska's complex is known to bind O2 reversibly. In the product, oxidation state of the metal ion center coordination geometry and mode of binding of O2, respectively are
