4.3 - Enzyme Inhibitors Flashcards
Why is it important to keep cellular conditions such as pH and temperature within narrow limits?
It is important to maintain these conditions within narrow limits to ensure enzyme activity is not delayed, allowing reactions to occur at a fast enough rate to sustain living processes, such as respiration.
What could happen if reactions occurred too quickly due to uncontrolled enzyme activity?
If reactions occur too quickly, it could lead to a buildup of excess products, which may disrupt cellular processes and resources.
Why are most living processes complex and involve multiple-step reaction pathways?
Living processes are rarely single reactions but are complex multi-step pathways that need to be closely regulated. This ensures they meet the organism’s needs without wasting resources.
How are different steps in reaction pathways controlled within cells?
Different steps in reaction pathways are controlled by different enzymes. By regulating enzyme activity at crucial points in these pathways, the rate and quantity of product formation can be controlled.
What role do cofactors and inhibitors play in enzyme activity?
Cofactors can activate enzymes, while inhibitors can inactivate enzymes or slow down their activity.
What are inhibitors and how do they affect enzyme function?
Inhibitors are molecules that prevent enzymes from carrying out their normal function of catalysis or slow them down, impacting the rate of the reaction.
What are the two types of enzyme inhibition?
The two types of enzyme inhibition are competitive inhibition and non-competitive inhibition.
What is competitive inhibition?
Competitive inhibition occurs when a molecule, similar in shape to the substrate, binds to the enzyme’s active site, preventing the substrate from binding and inhibiting the enzyme’s function.
How does a competitive inhibitor affect enzyme activity?
A competitive inhibitor competes with the substrate for binding to the active site of the enzyme. This reduces the number of substrate molecules that can bind to the active sites, thereby slowing down the rate of the reaction.
What factors determine the degree of competitive inhibition?
The degree of inhibition depends on the relative concentrations of the substrate, inhibitor, and enzyme. If the substrate concentration is high, it can outcompete the inhibitor.
Are the effects of competitive inhibitors reversible?
Most competitive inhibitors only bind temporarily to the active site, so their effect is reversible. However, some exceptions, such as aspirin, have irreversible effects.
How does a competitive inhibitor affect the rate of reaction?
A competitive inhibitor reduces the rate of reaction for a given concentration of substrate, but it does not change the Vmax of the enzyme.
Can a competitive inhibitor be overcome by increasing the substrate concentration?
Yes, if the substrate concentration is increased enough, the increased number of substrate molecules can outcompete the inhibitor, allowing the enzyme to reach its original Vmax.
What are statins and how do they work as competitive inhibitors?
Statins are competitive inhibitors of an enzyme involved in cholesterol synthesis. They are prescribed to reduce blood cholesterol levels, which helps lower the risk of heart disease.
How does aspirin act as a competitive inhibitor?
Aspirin irreversibly inhibits the active site of COX enzymes, preventing the synthesis of prostaglandins and thromboxane, which are chemicals responsible for pain and fever.
