What is the Difference Between Non-Competitive and Allosteric Inhibition?
🆚 Go to Comparative Table 🆚The main difference between non-competitive and allosteric inhibition lies in the way they affect enzyme activity and the specific sites they bind to on the enzyme. Here are the key differences:
- Non-competitive inhibition:
- The inhibitor binds to a site other than the active site, often causing distortion of the enzyme's shape, rendering it non-functional.
- The maximum rate of catalyzed reaction (Vmax) decreases, while the substrate concentration (Km) remains unchanged.
- Non-competitive inhibition is a catch-all term for non-physiological inhibition that does not compete with the substrate for substrate binding to the enzyme.
- Allosteric inhibition:
- The inhibitor binds to an allosteric site, which is a site other than the active site.
- Allosteric inhibition generally acts by switching the enzyme between two alternative states: an active form and an inactive form.
- The Vmax remains unchanged, and the Km value increases in allosteric inhibition.
- Allosteric inhibition is designed into the proteins and represents an important physiological process.
In summary, both non-competitive and allosteric inhibition involve binding to sites other than the active site, but they differ in their effects on enzyme activity and the specific site they bind to. Non-competitive inhibition is a broader term that includes various types of non-physiological inhibition, while allosteric inhibition specifically refers to inhibition that changes the enzyme's activity by binding to an allosteric site.
Comparative Table: Non-Competitive vs Allosteric Inhibition
The difference between non-competitive and allosteric inhibition can be summarized in the following table:
| Feature | Non-Competitive Inhibition | Allosteric Inhibition |
|---|---|---|
| Definition | Inhibition of an enzyme by binding to a location other than the active site, typically an allosteric site. | Inhibition of an enzyme by changing its shape or conformation, usually by binding to an allosteric site. |
| Active Site | occurs at an allosteric site, not the active site | Both active and allosteric sites can be involved. |
| Effect on Reaction Rate | Decreases the Vmax (maximal rate) while leaving the Km (Michaelis constant) unchanged. | Increases the Km and leaves the Vmax unchanged. |
| Inhibitor Type | Cannot be competitive since it binds to an allosteric site, not the active site. | Can be competitive or non-competitive, depending on the specific form of allosteric inhibition. |
| Examples | Conversion of pyruvate kinase into pyruvate, where an amino acid called Alanine inhibits the enzyme pyruvate kinase during glycolysis. | Control of ATP production in cells, where ATP acts as an inhibitor but ADP is an allosteric activator. |
In summary, non-competitive inhibition involves the binding of an inhibitor to an allosteric site, which affects the maximal rate of the reaction but not theMichaelis constant. On the other hand, allosteric inhibition can involve both active and allosteric sites, and it affects the Michaelis constant while leaving the maximal rate unchanged.
- Competitive vs Noncompetitive Inhibition
- Allosteric vs Non-allosteric Enzymes
- Allosteric vs Covalent Modulation
- Allosteric Site vs Active Site
- Positive vs Negative Allosterism
- Reversible vs Irreversible Inhibition
- Competitive vs Noncompetitive ELISA
- Concerted vs Sequential Model of Allosterism
- Allelopathy vs Competition
- Enzyme Inhibitor vs Enzyme Inducer
- Catalyst vs Inhibitor
- Allozymes vs Isozymes
- Enzyme Activator vs Enzyme Inhibitor
- Autogenic vs Reciprocal Inhibition
- Enzymatic vs Nonenzymatic Reaction
- Catalytic vs Non Catalytic Reaction
- Catecholamines vs Noncatecholamines
- Inverse Agonist vs Antagonist
- Excitatory vs Inhibitory Neurotransmitters