Enzyme inhibition

Enzyme inhibition activity may be irreversible or reversible.

Irreversible enzyme inhibition

In irreversible inhibition, inhibitor is called irreversible inhibitor that binds to the enzyme either covalently or non-covalently. Inhibitor dissociates very slowly from the enzyme and the enzyme’s catalytic activity is permanently inhibited.

Example:

The antibiotic penicillin acts as an irreversible inhibitor of the enzyme glycopeptide transpeptidase (also known as glycoprotein peptidase). Penicillin covalently binds with an essential serine residue in the active site of glycopeptide transpeptidase, an enzyme that acts to cross-link the peptidoglycan chains during the synthesis of the bacterial cell walls.

Once the cell wall synthesis is prevented, the bacterial cell undergo osmotic lysis and the bacterial growth is blocked.

Suicide inhibitor:

It is a type of irreversible inhibitor. Suicide inhibitor binds to the enzyme as a substrate and is initially processed by the normal catalytic mechanism. As a result of catalysis, the substrate is converted to a chemically reactive intermediate that inactivates the enzyme through covalent modification (that means the enzyme literally commits suicide).

The table below, represents the examples of irreversible enzyme inhibitors:

Reversible Enzyme inhibition:

In reversible inhibition, the inhibitor is called reversible inhibitor, binds non covalently to the enzyme. It dissociates rapidly from the enzyme. The effect of a reversible inhibitor is reversed after dissociation of inhibitor from enzyme. There are three common types of reversible inhibition.

The links of the types of reversible inhibition is presented below, please go through it.

1. Competitive inhibition: https://thebiologyislove.com/competitive-inhibition-graph/
2. Uncompetitive inhibition: https://thebiologyislove.com/uncompetitive-inhibition/
3. Noncompetitive inhibition: https://thebiologyislove.com/noncompetitive-inhibition/
4. Mixed- noncompetitive inhibition: https://thebiologyislove.com/mixed-noncompetitive-inhibition/

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