Enzyme Catalysis and the Outcome of Biochemical Reactions

Enzyme catalysis has been studied as a supportive process in biochemical reactions since the 1800s. The conventional paradigm states that a catalyst accelerates a chemical reaction without affecting its equilibrium) outcome. This notion was formed by decades of analysis of biochemical catalysis under the conditions defined by Henri in 1903, which stipulate that enzyme, substrate and the enzyme-substrate complex are at equilibrium, that a fixed amount of substrate is added at the onset of the reaction, that the substrate concentration is much larger than the enzyme concentration and not affected by the formation of an enzyme-substrate complex (measurement of initial reaction velocity), and that there is no change in enzyme concentration over time. These constraints were developed into the Michaelis-Menten equation (and with the even more restrictive assumption of irreversible reaction steps into the van Slyke equation). They were somewhat released by Briggs and Haldane, who defined quasi-steady state conditions and rephrased these equations to