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What happens to Km in the presence of a competitive inhibitor?
What happens to Km in the presence of a competitive inhibitor?
Non-competitive inhibitors bind to the active site of an enzyme.
Non-competitive inhibitors bind to the active site of an enzyme.
False
List one example of a drug that acts as a non-competitive inhibitor.
List one example of a drug that acts as a non-competitive inhibitor.
There are several possibilities such as certain cancer chemotherapy agents.
The drug __________ is used for the treatment of gout and acts as a competitive inhibitor.
The drug __________ is used for the treatment of gout and acts as a competitive inhibitor.
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Match the type of inhibitor with its characteristic:
Match the type of inhibitor with its characteristic:
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Which of the following statements is true regarding non-competitive inhibitors?
Which of the following statements is true regarding non-competitive inhibitors?
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Allosteric inhibitors bind to the active site of the enzyme.
Allosteric inhibitors bind to the active site of the enzyme.
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What is a common example of an allosteric inhibitor mentioned?
What is a common example of an allosteric inhibitor mentioned?
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In feedback inhibition, the _____ product inhibits the activity of an early enzyme.
In feedback inhibition, the _____ product inhibits the activity of an early enzyme.
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Match the following enzyme inhibition types with their characteristics:
Match the following enzyme inhibition types with their characteristics:
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Study Notes
Enzyme Inhibition Lecture Notes
- The lecture covered enzyme inhibition, specifically focusing on different types of enzyme inhibition, comparisons of various inhibitors, and examples of drugs acting as enzyme inhibitors in clinical practice.
Lecture Objectives
- Explain the different types of enzyme inhibition.
- Compare reversible competitive to non-competitive enzyme inhibitors and allosteric inhibitors.
- List some examples of drugs acting as enzyme inhibitors in clinical practice.
Why Need Enzyme Inhibitors?
- This section discusses the necessity of enzyme inhibitors.
Types of Enzyme Inhibition
-
Reversible Inhibitors:
- Competitive: Structural similarity to the substrate, competes for the active site, reversible by increasing substrate concentration. Increased Km, Vmax constant, increased slope on Lineweaver-Burk plot.
- Non-competitive: No structural similarity to the substrate, binds to a site other than the active site, absolute concentration of inhibitor, not reversed by increasing substrate concentration. Km constant, decreased Vmax, increased slope on Lineweaver-Burk plot.
- Allosteric: Small organic molecules bind to an allosteric site, changing enzyme conformation, affecting substrate binding, Km increased or Vmax decreased.
-
Irreversible Inhibitors:
- Cofactor/coenzyme: Inhibitor interferes with cofactor/coenzyme binding.
- Denaturation/ppt: Inhibitor causes enzyme denaturation.
- SH group: Inhibitor reacts with SH group of the enzyme.
- Anti-enzymes: Inhibitor is a protein that inhibits specific enzymes.
Competitive Inhibitors (Substrate Analogue Inhibitors)
- Structural similarity between substrate and inhibitor.
- Both compete for the active site.
- Relative concentration of substrate and inhibitor.
- Reversed by increasing substrate concentration.
- Km increased, Vmax constant.
- The slope is increased on Lineweaver-Burk plot
Examples of Competitive Inhibitors
- Sulfanilamide: Bacteriostatic, a PABA analogue.
- Allopurinol: Used in gout treatment.
- Dicumarol & Warfarin: Anti-coagulants.
- Statins: Competitive inhibitors of HMG-CoA reductase, used in hypercholesterolemia treatment.
Non-Competitive Inhibitors
- No structural similarity between substrate and inhibitor.
- No competition for the active site.
- Bind to a site other than the active site.
- Absolute concentration of inhibitor.
- Not reversed by increasing substrate concentration.
- Km constant, Vmax decreased.
- The slope is increased on Lineweaver-Burk plot.
Examples of Non-Competitive Inhibitors
- Captopril: Angiotensin-converting enzyme (ACE) inhibitor used in hypertension treatment.
Allosteric Inhibitors
- Small organic molecules.
- Bind to the allosteric site.
- Produce conformational change, making binding to substrate less suitable (decrease enzyme activity).
- Km increased or/and Vmax decreased.
Allosteric Feedback Inhibition
- End product inhibits the activity of an early enzyme within a pathway.
- Usually irreversible.
- Important in metabolic regulation.
- ATP is an example (inhibits phosphofructokinase, a key enzyme in glycolysis).
Summary
- Reversible enzyme inhibition.
- Competitive inhibitors.
- Non-competitive inhibitors.
- Allosteric inhibitors.
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Description
This quiz covers key concepts of enzyme inhibition, focusing on various types such as reversible competitive and non-competitive inhibitors. It also discusses their clinical applications and the importance of enzyme inhibitors in medicinal chemistry. Test your understanding with questions based on these crucial topics!
