Enzyme Inhibition and Reaction Rate of Enzyme
Enzyme Inhibition and Reaction Rate of Enzyme is an important topic in the biochemistry. We use the study in many ways. first, we should know the classification of the Enzyme.
There are two kinds of enzyme inhibition-
- Reversible Inhibition and
- Irreversible Inhibition.
Again there are three kinds of Reversible Inhibition —
- Competitive Inhibition
- Uncompetitive Inhibition and
- Non-competitive Inhibition.
Today we will discuss only Competitive Inhibition.
Competitive Inhibition: Inhibitor (I) binds only to Enzymes (E), but not to the enzyme-Substrate complex (ES) and inhibits the Enzymes (E) to function is known as the Competitive Inhibition. It is a real kind of Inhibition. It happens in real for an Enzyme. A competitive inhibitor is reversible and has a structure like a substrate to fit the active site of the enzyme. So Competitive competes with the substrate for the active site of the enzymes. Once It fit with the active site of an Enzyme it makes an Enzyme-Inhibitor complex (EI), the Substrate can’t bind with the Enzyme. So the Inhibition takes place. But it is a reversible process so the Enzyme-Inhibitor complex (EI) breaks down and again enzyme becomes functional.
Competitive inhibition can be reversed by increasing substrate concentration
The competitive inhibition can be reversed by increasing the concentration of the substrate. As the concentration of the substrate is increasing the number of substrate molecules increasing around the active site of the Enzymes. So the Inhibitor molecules are released from the active site of the Enzyme. Then the Substrate molecules can bind again to the active site of the Enzyme.
In the presence of a competitive inhibitor, Michaelis-Menten equation–
this is the Lineweaver-Burk equation in the presence of a competitive inhibitor.
In the competitive inhibition, the value of Km changes while Vmax does not.
- Effect on Vmax: Increasing substratum concentration [ S ] reverses the impact of a competitive inhibitor. The reaction velocity reaches the Vmax observed in the lack of inhibitors at a sufficiently elevated concentration of the substratum.
Effect on Km: For a specified substrate, a competitive inhibitor improves the evident km. This means that more substrate is needed in the presence of a competitive inhibitor to achieve 1⁄2Vmax
- Effect on the Lineweaver-Burk plot: Competitive inhibition shows a characteristic Lineweaver-Burk plot in which the plots of the inhibited and uninhibited reactions intersect on the y-axis at 1/Vmax (Vmax is unchanged), and show different x-axis intercepts, indicating that the apparent Km is increased in the presence of the competitive inhibitor.
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