Protein Biochemistry - Enzyme Inhibition

These flashcards cover key concepts related to protein biochemistry, specifically enzyme inhibition, including types of inhibitors, mechanisms, and kinetic parameters.

What distinguishes irreversible inhibition from reversible inhibition?

Irreversible inhibition leads to permanent inactivation of an enzyme, while reversible inhibition allows for equilibrium between the enzyme and inhibitor.

Give an example of an irreversible inhibitor and explain its mechanism.

Aspirin is an irreversible inhibitor; it covalently modifies cyclooxygenase (COX) to reduce inflammation by blocking the active site.

What do KMapp and Vmax app represent?

KMapp and Vmax app are observed values of the kinetic parameters affected by the presence of an inhibitor.

What is competitive inhibition?

Competitive inhibition occurs when an inhibitor competes with the substrate for the enzyme's binding site, often resembling the substrate.

How does uncompetitive inhibition differ from competitive inhibition?

Uncompetitive inhibition occurs when the inhibitor binds directly to the enzyme-substrate complex, rather than the free enzyme.

What is the Cheng-Prusoff equation used for?

The Cheng-Prusoff equation is used to relate IC50 values to KI for competitive inhibitors.

What is the significance of IC50 in enzyme inhibition?

IC50 is the concentration of an inhibitor required to inhibit an enzyme by 50% and is used for comparing inhibitor potencies.

What does a selectivity ratio measure in enzyme inhibition?

A selectivity ratio measures the preference of an inhibitor for one enzyme over another, indicating desired selectivity to avoid side effects.

What happens to Vmax app in the presence of a competitive inhibitor?

In competitive inhibition, Vmax app remains unchanged, while KMapp increases.

What is the effect of mixed inhibition on enzyme kinetics?

Mixed inhibition can affect both the enzyme and the enzyme-substrate complex, altering both KMapp and Vmax app.