So let's begin with Kcat. So Kcat, as we discussed in the previous lecture, is known as the turnover number. And Kcat basically describes how many of the substrate molecules are transformed into the product molecules per unit time, per single active site, per single enzyme. So KCAD, the turnover number, tells us how many substrate molecules are transformed into product molecules by single active side per unit time, usually per second. Now? What about Km?