Suppose that the rate of formation of product(ks) is much faster than the approaches h]. Thus the ultimate limit on the value of 3/KM is set by G 1a rate of dissociation of the Es complex (R2). The value of k3/ Km ther the rate of formation of the ES complex. Tus rale cannol be /aster than the di- Ausion-controlled encounter o/an enzyne and ils substrale. Diffusion limits the value of k, so that it cannot be higher than between 108 and 109M-Is-I Hence, the upper limit on ha/KM is between 108 and 109M-Is-I 31 3/AM <k (36) 。+k: 3