And so that's why we call asparty transcarbomoylease an allosteric enzyme. Now, what we want to focus on in this lecture is the actual structure of asperty transcarbomolise. And then we want to discuss what happens to that structure of the enzyme once the substrate molecule actually binds onto the active side of the enzyme. So let's begin by describing the structure. Now, this enzyme has coordinate structure. And what that means is it consists of multiple subunits.