Non-Competitive Inhibition

Introduction

• Non-competitive inhibition is a type of enzyme regulation where an inhibitor molecule does not bind to the enzyme's active site but attaches to a different part of the enzyme.
• This binding causes a change in the shape of the enzyme's active site, preventing the substrate from binding effectively.

Mechanism of Non-Competitive Inhibition

• Non-competitive inhibitors do not compete with the substrate for the active site.
• Instead, they bind to an allosteric site on the enzyme, which is a region other than the active site.
• When the inhibitor binds to this site, it causes a structural change in the enzyme's shape.

Effect on Enzyme Activity

• The alteration in the enzyme's shape induced by non-competitive inhibition makes the active site less accessible or suitable for the substrate to bind.
• As a result, the reaction rate of the enzyme is decreased.

Irreversible Nature

• Unlike competitive inhibition, non-competitive inhibition cannot be reversed by increasing the concentration of the substrate.
• Once the non-competitive inhibitor binds to the enzyme, it remains inhibited until the inhibitor is removed.

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Non-Competitive Inhibition

Examples of Non-Competitive Inhibitors

• Non-competitive inhibitors include substances such as cyanide, mercury, and silver.

Impact on Metabolic Pathways

• Both competitive and non-competitive inhibitors can affect the rates of reactions in metabolic pathways, regulating the overall flow of these pathways.