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Competitive inhibition can be overcome by adding more substrate to the reaction, which increases the chances of the enzyme and substrate binding. As a result, competitive inhibition alters only the K m, leaving the V max the same. [3] This can be demonstrated using enzyme kinetics plots such as the Michaelis–Menten or the Lineweaver-Burk plot.
Effects of different types of inhibition on the double-reciprocal plot. When used for determining the type of enzyme inhibition, the Lineweaver–Burk plot can distinguish between competitive, pure non-competitive and uncompetitive inhibitors. The various modes of inhibition can be compared to the uninhibited reaction.
The plot of against has often been called a "Michaelis–Menten plot", even recently, [7] [8] [9] but this is misleading, because Michaelis and Menten did not use such a plot. Instead, they plotted v {\displaystyle v} against log a {\displaystyle \log a} , which has some advantages over the usual ways of plotting Michaelis–Menten data.
The plot is occasionally attributed to Augustinsson [5] and referred to the Woolf–Augustinsson–Hofstee plot [6] [7] [8] or simply the Augustinsson plot. [9] However, although Haldane, Woolf or Eadie were not explicitly cited when Augustinsson introduced the versus / equation, both the work of Haldane [10] and of Eadie [3] are cited at other places of his work and are listed in his ...
Two equations listed below that are referred to as non-competitive substrate inhibition and competitive substrate inhibition models respectively by Shuler and Michael in Bioprocess Engineering: Basic Concepts. Note that the Haldane equation above is a special case of the following non-competitive substrate inhibition model, where KI >>Ks. [1]
When a non-competitive inhibitor is added the Vmax is changed, while the Km remains unchanged. According to the Lineweaver-Burk plot the Vmax is reduced during the addition of a non-competitive inhibitor, which is shown in the plot by a change in both the slope and y-intercept when a non-competitive inhibitor is added. [8]
Uncompetitive inhibition (which Laidler and Bunting preferred to call anti-competitive inhibition, [1] but this term has not been widely adopted) is a type of inhibition in which the apparent values of the Michaelis–Menten parameters and are decreased in the same proportion.
On a Lineweaver-Burk plot, the presence of a noncompetitive inhibitor is illustrated by a change in the y-intercept, defined as 1/V max. The x-intercept, defined as −1/K M, will remain the same. In competitive inhibition, the inhibitor will bind to an enzyme at the active site, competing with the substrate.