And so because of that, every time an oxygen binds onto one of the sites, it basically creates a conformational change in the structure of that enzyme. And that induces it increases the affinity of the other sites for that same substrate, for that oxygen molecule. And so what that implies is the reason ATCAs exhibits cooperative behavior is because it consists of multiple subunits, and those subunits must have additional active sites. And so when one of those active sites Is filled with the substrate molecules, such as the aspartate, the other active sites become much more likely to actually bind to that substrate molecule. That's why we have this sigmoil curve. So, this cooperative behavior implies that atcase must consist of multiple subunits and hence multiple active sites.