Under appropriate denaturing conditions, hemoglobin can dissociate into four separate subunits. An isolated alpha subunit binds oxygen, but the O2-saturation curve is hyperbolic rather than sigmoid. In addition, the binding of oxygen to an isolated alpha subunit is not affected by the presence of H+, CO2, or BPG. What do these observations indicate about the source of the cooperativity in hemoglobin?

Below is the O₂ binding curve for adult Hb in whole blood (containing BPG) shown in red (labelled Hb). Fraction of Hb bound with Oxygen 1.0 0.8 0.6 0.4 0.2 0.0 0 20 40 pO2 (torr) 60 80 ABC c. Which curve lacks cooperativity? [Select] Hb 100 a. Which curve is the best representation for stripped Hb (pure hemoglobin with heme, but no other small allosteric molecules associated)? [Select] b. Which curve has the lowest affinity (as measured by the p50)? [Select]

72.4.1

In Charles’ blood, the partial pressure of CO in the blood (0.4 mm Hg) is far lower than the partial pressure of O2, yet the percent saturation of hemoglobin by each gas is approximately equal. What does this tell you about the affinity of hemoglobin for CO?

What is the equilibrium expression of oxygenated hemoglobin to deoxygenated hemoglobin?

Below are multiple oxygen binding affinity curves for hemoglobin. The affinity curve for normal hemoglobin in blood is represented by curve "D," at a pH of 7.2 and at a concentration of 5mM BPG and 26 mM CO2. O₂ saturation (%) 100 Answer 1: B Answer 2: [Select] Answer 3: B Answer 4: 80 A 60 1. How would changes to acidity, BPG concentration and CO₂ levels affect the binding affinity curve and p50? lower than Answer 5: E 40 1. BPG concentration is decreased to 3mM: The binding affinity curve would look like B. The p50 would be lower than normal (D). 2. pH is increased to 7.6: The binding affinity curve would look like B. The p50 would be [Select] normal (D). 20 3. CO₂ concentration is increased to 30 mM: The binding affinity curve would look like. [Select] The p50 would be Answer 6: 0 normal (D). II. The hemoglobin has been treated with a denaturing solution which disrupts quaternary structure only, and has a binding affinity resembling myoglobin. The binding affinity curve would look…

Carbon monoxide (CO) is a colorless, odorless gas produced during combustion of fuels (for example, by car engines and furnaces).  The following graph depicts an oxygen dissociation curve in the absence and presence of varying amounts of carbon monoxide. Based on these results, in the presence of 20% CO, when PO2 is 90mmHg you should expect each hemoglobin molecule to have _____ molecule(s) of O2 bound a) 1 b) 2 c) 3 d) 4