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Enzyme Inhibition


Inhibitors that do not contribute to the development of the product carry out the inhibition. The inhibitors can impact both the substrate and the enzyme. The stoppage of enzyme activity is referred to as enzyme inhibition.

These enzyme inhibitors can attach to active areas and halt or inhibit further activity. This form of binding can be both reversible and irreversible.

Table of Contents

Types of Enzyme Inhibition

Depending on the specific action of the inhibitor used, enzyme inhibition might be reversible or irreversible. Enzyme inhibitors can block the binding site, preventing the substrate from attaching to the active site, and decreasing the enzyme’s catalytic activity.

Reversible inhibitors attach to enzymes via non-covalent interactions like hydrogen bonds, hydrophobic contacts, and ionic bonds. When attached to an enzyme, reversible inhibitors do not undergo chemical reactions and can be easily eliminated by dilution or dialysis.

On the other hand, irreversible inhibitors frequently covalently alter an enzyme, preventing the reversal of inhibition.

Enzyme Inhibitors and Inhibition

There are three types of enzyme inhibition reactions.

  1. Competitive Inhibition
  2. Non-competitive Inhibition
  3. Uncompetitive Inhibition

Competitive Inhibition

A molecule other than the substrate binds to the enzyme’s active site, causing competitive inhibition. The inhibitor (molecule) has a structural and chemical similarity to the substrate (hence able to bind to the active site). The competitive inhibitor hinders substrate binding by blocking the active site. Since the inhibitor competes with the substrate, increasing the substrate concentration reduces the inhibitor’s actions.

Competitive Inhibition

Non-Competitive Inhibition

A chemical binds to a location other than the active site in non-competitive inhibition (an allosteric site). When the inhibitor binds to the allosteric site, the enzyme’s active site undergoes a structural shift. The active site and substrate no longer share affinity as a result of this alteration, preventing the substrate from binding. Increased substrate levels will not be able to reverse the inhibitor’s action since the inhibitor is not in direct competition with the substrate.

Non-Competitive Inhibition

Uncompetitive Inhibition

The inhibitor binds only to the substrate-enzyme complex in uncompetitive inhibition. In reactions involving two or more substrates or products, uncompetitive inhibition is common. Non-competitive inhibition can occur with or without the presence of the substrate, whereas uncompetitive inhibition requires the formation of an enzyme-substrate complex.

Uncompetitive Inhibition

Applications of Enzyme Inhibition

In the pharmaceutical and medical industries, enzyme inhibitors are essential. Pharmacologists benefit from a basic grasp of inhibitor activity during the development of new therapeutic medicines.

Insecticides such as malathion, herbicides such as glyphosate, and disinfectants such as triclosan are all examples of artificial inhibitors. Other synthetic enzyme inhibitors inhibit acetylcholinesterase, an enzyme that breaks down acetylcholine, and are utilised in chemical warfare as nerve agents.

Frequently Asked Questions on Enzyme Inhibition

What is enzyme inhibition and what are the types?

A decrease in enzyme-related processes, enzyme production, or enzyme activity is referred to as enzyme inhibition. Competitive, Non-competitive, and Uncompetitive are the three types of inhibition reactions.

What is an allosteric site?

The allosteric site is a molecule’s ability to stimulate or inhibit (or turn off) enzyme activity. It’s not the same as an enzyme’s active site, which is where substrates bind.

What are the types of reversible inhibitor reactions?

There are four types of reversible inhibition reactions. They are competitive inhibition, non-competitive inhibition, uncompetitive inhibition, and mixed inhibition.

What is covalent inactivation?

Irreversible inhibition is also known as covalent inactivation. Since they usually covalently change an enzyme, inhibition is irreversible.

How animals and plants can act as inhibitors?

Animals and plants have acquired the ability to produce a wide range of toxic compounds, such as secondary metabolites, peptides, and proteins that can function as inhibitors. Paclitaxel (taxol), an organic chemical discovered in the Pacific yew tree, binds tightly to tubulin dimers in the cytoskeleton, and prevents them from forming microtubules.

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