What is competitive inhibition in the context of enzyme activity?
Competitive inhibition occurs when a substance mimics the substrate of an enzyme, competing for binding at the active site and reducing the enzyme's activity.
How does competitive inhibition affect the Km of an enzyme-catalyzed reaction?
Competitive inhibition increases the apparent Km of the enzyme without affecting Vmax.
Can Vmax be achieved in the presence of a competitive inhibitor?
Yes, Vmax can still be achieved in competitive inhibition by increasing substrate concentration.
How does competitive inhibition differ from non-competitive inhibition?
In competitive inhibition, the inhibitor binds the active site, whereas, in non-competitive inhibition, the inhibitor binds elsewhere on the enzyme.
What is an example of a competitive inhibitor in pharmacology?
Methotrexate is a competitive inhibitor of dihydrofolate reductase, an enzyme involved in nucleotide synthesis.
How do enzymes overcome competitive inhibition in nature?
Enzymes can overcome competitive inhibition by increasing the concentration of the natural substrate.
How does competitive inhibition appear on a Lineweaver-Burk plot?
In competitive inhibition, Lineweaver-Burk plots show lines with the same y-intercept but different slopes (increased Km).
Is competitive inhibition reversible?
Yes, competitive inhibition is typically reversible.
What does a low Ki value indicate about a competitive inhibitor?
A low Ki value indicates a strong inhibitor, requiring lower concentrations to effectively inhibit enzyme activity.
What structural characteristics make a molecule a good competitive inhibitor?
Structural similarity to the enzyme's substrate makes a molecule a good competitive inhibitor.
In the context of enzyme inhibition, what is allosteric inhibition, and how does it differ from competitive inhibition?
Allosteric inhibition involves inhibitors binding to a site other than the active site, different from competitive inhibition where the inhibitor binds the active site.
What role does competitive inhibition play in regulating metabolic pathways?
Competitive inhibition plays a role by controlling the flux through pathways based on substrate and inhibitor availability.
How does competitive inhibition relate to enzyme specificity?
Competitive inhibition highlights the importance of enzyme specificity since inhibitors must closely resemble the substrate to compete effectively.
What is the biological significance of competitive inhibition?
Competitive inhibition regulates enzyme activity and thus plays a crucial role in controlling metabolic processes.
Can a competitive inhibitor be used as a drug to modulate enzyme activity?
Yes, competitive inhibitors are often used as drugs to selectively reduce enzyme activity in various conditions.