When all the active sites have been occupied, the reaction is complete, which means that the enzyme is at its maximum capacity and increasing the concentration of substrate will not increase the rate of turnover.
An equation with a high K m indicates that the enzyme does not bind as efficiently with the substrate, and V max will only be reached if the substrate concentration is high enough to saturate the enzyme.Īs the concentration of substrates increases at constant enzyme concentration, the active sites on the protein will be occupied as the reaction is proceeding. An equation with a low K m value indicates a large binding affinity, as the reaction will approach V max more rapidly. It can also be thought of as a measure of how well a substrate complexes with a given enzyme, otherwise known as its binding affinity. K m is the Michaelis-Menten constant which shows the concentration of the substrate when the reaction velocity is equal to one half of the maximal velocity for the reaction. V max is the maximal rate of the reaction. V 0 is the initial velocity of the reaction. The fraction / has been coined K m, or the Michaelis constant.Īccording to Michaelis-Menten's kinetics equations, at low concentrations of substrate,, the concentration is almost negligible in the denominator as K M >, so the equation is essentiallyĪt High substrate concentrations, > K M, and thus the term /( + K M) becomes essentially one and the initial velocity approached V max, which resembles zero order reaction. Rate of breakdown of ES = (k -1 + k 2) Īnd set equal to each other (Note that the brackets represent concentrations). The new reaction becomes:Īssuming steady state, the following rate equations may be written as: Therefore, the ES complex may dissolve back into the enzyme and substrate, or move forward to form product.Īt initial reaction time, when t ≈ 0, little product formation occurs, therefore the backward reaction rate of k -2 may be neglected. Likewise, for the reaction from the ES complex to E and P, the forward reaction rate is k 2, and the reverse is k -2.
The rate of the forward reaction from E + S to ES may be termed k 1, and the reverse reaction as k -1. Thus, the enzyme combines with the substrate in order to form the ES complex, which in turn converts to product while preserving the enzyme. The Michaelis-Menten equation arises from the general equation for an enzymatic reaction: E + S ↔ ES ↔ E + P, where E is the enzyme, S is the substrate, ES is the enzyme-substrate complex, and P is the product.
0 kommentar(er)
