Final answer:
BPG acts as a non-competitive inhibitor by binding to hemoglobin at an allosteric site, altering its affinity for oxygen. Its function is part of a vital physiological mechanism and this inhibition is reversible.
Step-by-step explanation:
Bisphosphoglycerate (BPG), a compound native to human red blood cells, acts as an allosteric regulator rather than a traditional inhibitor. BPG binds to hemoglobin, decreasing its affinity for oxygen which is a vital physiological mechanism to facilitate oxygen release in tissues. When discussing non-competitive inhibition, we refer to a scenario where an inhibitor binds to an enzyme at a location that is different from the active site (an allosteric site), which changes the shape of the enzyme and alters its activity. BPG binds to hemoglobin in such a way that it does not compete with oxygen, the substrate; therefore, BPG is considered to be a non-competitive inhibitor. This type of inhibition is also reversible, meaning the effect of BPG binding can be countered by changes in concentration or environmental conditions.