Michaelis–Menten equation & Kinetic parameters

The Michaelis–Menten equation is the rate equation for a one-substrate enzyme-catalyzed reaction. This equation relates the initial reaction rate (v0), the maximum reaction rate (Vmax), and the initial substrate concentration [S] through the Michaelis constant KM—a measure of the substrate-binding affinity. When S is saturating, it is quickly bound by free enzyme to form ES complexes. During the steady state, the rate of decomposition of the ES complex equals its formation. Later, S becomes exhausted and its concentration nears the total enzyme concentration: less substrate is available to the enzyme, and the fraction of total enzyme in a complex with substrate begins to decrease. Note that E is the unbound enzyme concentration, not the total concentration of enzyme: [E] + [ES] Pre-Steady State In the short time prior to the steady state, there is a burst of ES complex formation as substrate is quickly bound by empty enzyme. The sub-maximal rate of substrate utilization and product formation reflects the fact that it takes some time for the ES complexes to form. When S is saturating, it is quickly bound by free enzyme to form ES complexes. During the steady state, the rate of decomposition of the ES complex equals its formation. Later, S becomes exhausted and its concentration nears the total enzyme concentration: less substrate is available to the enzyme, and the fraction of total enzyme in a complex with substrate begins to decrease Note that E is the unbound enzyme concentration, not the total concentration of enzyme: [E], = [E] + (ES] Initially, the concentration of product increases slowly because the enzymes must first bind substrate before reacting. During the steady state S is saturating and the rate of product formation becomes constant (zero order with respect to S). Finally, as IS] nears [E]l, the rate of the reaction (product formation) slows over time, similar to a first-order reaction where S is in short supply. Kinetic parameters are parameters included in the reaction rate equations, such as adsorption equilibrium constants, rate constants, and reaction order.

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