What effect does CO2 binding have on hemoglobin?

When carbon dioxide (CO2) binds to hemoglobin, it has a significant influence on its conformation and function. CO2 binding promotes the transition of hemoglobin from the relaxed (R-state) to the tense (T-state) conformation. The T-state is associated with lower affinity for oxygen. This is part of the Bohr effect, where increased levels of CO2 in tissues promote oxygen release from hemoglobin, thus aiding in the delivery of oxygen to areas of high metabolic activity where CO2 concentration is elevated.

The binding of CO2 to hemoglobin occurs primarily at the amino terminal of the globin chains, forming carbamino compounds, which facilitates the switch to the T-state. In this state, hemoglobin is less effective at binding oxygen, allowing for more efficient oxygen unloading to tissues that require it. This mechanism is crucial for effective gas exchange and maintenance of acid-base balance in the blood.

The other choices do not accurately describe the impact of CO2 on hemoglobin's functionality. Thus, the correct understanding is that CO2 binding leads to a stabilization of the T-state, enhancing the release of oxygen where it is most needed.