During the Bohr effect, what happens when pH decreases?

During the Bohr effect, a decrease in pH leads to an increase in the concentration of hydrogen ions (H+) in the blood. This change in acidity affects the structure and function of hemoglobin. Specifically, the histidine residues within the hemoglobin molecule may become protonated rather than deprotonated, leading to the formation of salt bridges.

These salt bridges are interactions that stabilize the deoxygenated form of hemoglobin, facilitating the release of oxygen to the tissues that need it most (e.g., active muscles producing CO2 and lowering pH). The formation of these salt bridges increases hemoglobin's affinity for the deoxygenated state, thereby promoting oxygen release as pH drops.

This mechanism is crucial in physiological conditions where CO2 production is high, such as during exercise. In these situations, the reduced pH signals hemoglobin to release oxygen where it is most needed. Thus, the formation of salt bridges is a key feature of the Bohr effect, playing a vital role in the regulation of oxygen transport in response to tissue metabolism.