"\frac{d{x}}{d{t}} = k_{3}p = \frac{k_{3}e(a-x)}{a-x+\frac{k_{2}+k_{3}}{k_1}} This is Michaelis and Menten's [1913] equation, (k2 + k3)/k1 representing their constant Ks. […] It may be remarked that with this modification of their theory, Michaelis and Menten's analysis of the effects of the products of the reaction, or other substances which combine with the enzyme, still holds good."