Well, it doesn't actually seal off the active side entirely. Why? Well, because this molecule has to enter that particular active side. And we'll see that in this step, as we'll see in just a moment, this actually creates that entire sealing process, whereas seal off that active side completely. So we go from the open confirmation to the closed confirmation. And what this also does is upon the binding of the oxalo acetate to the active side of the citrate sentase, it creates an additional binding site in that active side that can now bind the CETO coenzyme A.