Control of Metabolic Pathways by Inhibition

Introduction

• Metabolic pathways are essential for various cellular processes, but their rates of reaction need to be regulated for optimal function.
• Enzymes play a central role in these pathways, and their activity can be influenced to control metabolic processes.

Gene Expression and Enzyme Presence

• Some enzymes in cells are always present due to continuous gene expression.
• Controlling the activity of these enzymes is crucial for regulating metabolic pathways.

Chemical Influences on Enzyme Activity

• Enzyme activity can be modulated by various chemicals, allowing for precise control over metabolic reactions.
• Inhibitors are chemicals that can be employed to regulate enzyme activity and the progress of metabolic pathways.

Types of Inhibition

• Inhibition refers to the process of slowing down or blocking enzyme activity. There are three primary types of inhibition:

1. Competitive Inhibition

• In this type of inhibition, a molecule similar in structure to the substrate competes with the substrate for binding to the enzyme's active site.
• When the inhibitor binds, it prevents the substrate from binding, effectively slowing down the reaction.

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Control of Metabolic Pathways by Inhibition

2. Non-competitive Inhibition

• Non-competitive inhibitors do not bind to the active site of the enzyme.
• Instead, they attach to a different site on the enzyme, altering its shape or structure.
• This change in enzyme conformation affects its ability to bind to the substrate and catalyse the reaction.

3. Feedback Inhibition

• Feedback inhibition is a regulatory mechanism in which the end product of a metabolic pathway acts as an inhibitor for an enzyme earlier in the pathway.
• This ensures that the pathway is only active when the end product is needed and prevents overproduction.