And so what that means is the concentration of that substrate under normal conditions is usually much smaller than the Km value. So if we are to pinpoint where the concentration of that substrate in our cells usually is, it's somewhere around, let's say, this quantity here. So it ranges between this X value range here. And so what that basically means is inside our cells, the efficiency, or I should say not the efficiency, but the rate, the velocity of that enzyme is usually much lower than its maximum velocity. So for example, if the concentration is somewhere here, then the corresponding rate will be somewhere here, much smaller than that maximum velocity. Now, what we want to basically explore in this lecture is how to actually measure the catalytic efficiency of the enzyme inside our cell.