When blood is in the lungs, where oxygen is plentiful, oxygen easily binds to the first subunit and then quickly fills up the remaining ones. Then, as blood circulates through the body, the oxygen level drops while that of carbon dioxide increases. In this environment, hemoglobin releases its bound oxygen.
Explanation: Since most enzymes are proteins, it will be produced at the ribosomes. It may have an active and an inactive form. Which means another substance Will turn it on or off.
