Now, the final thing I'd like to discuss about the Concerted model is what's the limitation of the Concerted model? What is the problem? Well, the problem is the following. Let's take a look at the following diagram. What this diagram basically describes is when our oxygen binds onto one of the heme groups of hemoglobin, this is the state that will predominate. Now, according to the Concerted model, this structure of this polypeptide that contains the bound oxygen does not change its conformation.