So as we increase at the beginning we see that there is a linear increase. So that means the velocity is directly proportional to the concentration of S. But then the rate slowly begins to decrease, the slope decreases and it levels off and eventually it reaches a maximum velocity. And that is given by this horizontal green line. So that horizontal green line describes the maximum possible rate at which the enzyme can operate on that particular substrate. And in the previous lecture, when we discussed the turnover number Kcat, we basically gave an equation that describes how to actually obtain the maximum velocity. So we said that v max of an enzyme is equal to the product of the turnover number KCAD and the concentration, the total concentration of the enzyme.