2,3-BPG is known as a ___________ regulator that stabilizes the T state of hemoglobin.

2,3-Bisphosphoglycerate (2,3-BPG) acts as a negative heterotropic regulator of hemoglobin, meaning it binds to hemoglobin at a site distinct from the oxygen binding site and decreases the affinity of hemoglobin for oxygen. This is particularly important in facilitating the release of oxygen to tissues that need it, such as actively metabolizing cells.

The T state, or taut state, of hemoglobin is associated with a lower affinity for oxygen, which allows hemoglobin to effectively release oxygen in areas where it’s needed. 2,3-BPG binds preferentially to deoxygenated hemoglobin, stabilizing this T state and promoting the unloading of oxygen. This physiological role is vital for ensuring that oxygen delivery meets the metabolic demands of tissues, especially under conditions of low oxygen availability, such as high altitude or vigorous exercise.

In contrast, options representing positive regulators would suggest increased affinity for oxygen, which does not reflect the role of 2,3-BPG. Additionally, homotropic regulation refers to molecules that bind to the same site as the substrate and influence binding, which is not applicable here since 2,3-BPG binds at a different site, qualifying it as a heterotropic regulator. Understanding these specific