CO2 Binding to Hemoglobin and Bohr Effect

Steps:

• Carbon dioxide reacts with hemoglobin's amino groups to form carbaminohemoglobin.
• Carbaminohemoglobin formation increases hemoglobin's affinity for protons (H+).
• This lowers hemoglobin's oxygen affinity via the Bohr effect.
• The oxygen dissociation curve shifts right, facilitating oxygen unloading in tissues.

Why B is correct:

• Carbaminohemoglobin contributes to the Bohr effect, defined as decreased hemoglobin oxygen affinity due to CO2 and low pH, shifting the curve right per the equation HbO2 + CO2 + H2O ⇌ HbCO2 + H+ + OH-.

Why the others are wrong:

• A: Shift is right, not left, for CO2 effects.
• C: Carboxyhemoglobin forms from carbon monoxide (CO), not CO2.
• D: Carboxyhemoglobin is incorrect compound; shift for CO2 is right, not left.

Final answer: B