Factors Affecting Enzyme Activity
42 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which type of enzyme inhibition occurs when an inhibitor binds to the active site, preventing substrate binding?

  • Allosteric inhibition
  • Competitive inhibition (correct)
  • Uncompetitive inhibition
  • Non-competitive inhibition

    • In non-competitive inhibition, the binding of the inhibitor affects which aspect of enzyme activity?

  • Only the substrate binding affinity
  • Both maximum velocity (V_max) and Michaelis constant (K_m)
  • Michaelis constant (K_m) only
  • Maximum velocity (V_max) only (correct)

    • What is the characteristic outcome of uncompetitive inhibition on a reaction's kinetics?

  • Increase in K_m
  • Decrease in V_max and K_m (correct)
  • Decrease in K_m without effect on V_max
  • Increase in V_max without changing K_m

    • How do allosteric enzymes differ from standard enzymes in terms of regulation?

    <p>Their activity is regulated by binding of molecules at sites other than the active site</p> Signup and view all the answers

    What is feedback inhibition primarily used for in biological pathways?

    <p>To regulate the concentration of products in a metabolic pathway</p> Signup and view all the answers

    Which statement about competitive inhibitors is TRUE?

    <p>Their effect can be overcome by increasing substrate concentration</p> Signup and view all the answers

    Which of the following is NOT a characteristic of uncompetitive inhibition?

    <p>It can be overcome by excess substrate</p> Signup and view all the answers

    Which phenomenon describes when the product of a reaction acts to inhibit an earlier step in the pathway?

    <p>Feedback inhibition</p> Signup and view all the answers

    Which type of enzyme inhibition is characterized by the inhibitor binding only to the enzyme-substrate complex, thereby preventing the reaction from proceeding?

    <p>Uncompetitive inhibition</p> Signup and view all the answers

    What describes competitive inhibition in enzyme activity?

    <p>Inhibitor and substrate compete for the active site.</p> Signup and view all the answers

    Which type of inhibition affects both the enzyme and the enzyme-substrate complex equally?

    <p>Noncompetitive inhibition</p> Signup and view all the answers

    Feedback inhibition in a metabolic pathway generally serves to:

    <p>Regulate the pathway by inhibiting an upstream enzyme.</p> Signup and view all the answers

    Allosteric enzymes are differentiated from other enzymes because they:

    <p>Can exist in multiple conformations that affect activity.</p> Signup and view all the answers

    What happens to the Km value of an enzyme in the presence of a competitive inhibitor?

    <p>It increases.</p> Signup and view all the answers

    In the presence of a noncompetitive inhibitor, what effect would you expect on the maximum rate (Vmax) of the enzyme reaction?

    <p>Vmax decreases.</p> Signup and view all the answers

    An allosteric activator would typically lead to which of the following outcomes?

    <p>Enhancement of enzyme activity.</p> Signup and view all the answers

    Which statement accurately describes the relationship between substrate concentration and enzyme activity?

    <p>Activity tends to reach a maximum level at high substrate concentrations.</p> Signup and view all the answers

    What distinguishes a competitive inhibitor from other types of enzyme inhibitors?

    <p>It competes with the substrate for the active site of the enzyme.</p> Signup and view all the answers

    In noncompetitive inhibition, what happens to the enzyme kinetics?

    <p>The maximum reaction rate decreases, but the binding affinity remains unchanged.</p> Signup and view all the answers

    What is the effect of uncompetitive inhibitors on enzyme activity?

    <p>They decrease both the maximum rate and the apparent binding affinity of the enzyme.</p> Signup and view all the answers

    Which of the following best describes allosteric enzymes?

    <p>They can be activated or inhibited by various molecules that bind outside the active site.</p> Signup and view all the answers

    What role does feedback inhibition play in metabolic pathways?

    <p>It limits the activity of an enzyme involved in the pathway when concentrations of the product are high.</p> Signup and view all the answers

    Which statement accurately describes competitive feedback inhibition?

    <p>The inhibitor prevents the substrate from binding to the enzyme.</p> Signup and view all the answers

    Which of the following best explains noncompetitive feedback inhibition?

    <p>The inhibitor and substrate can bind to the enzyme simultaneously.</p> Signup and view all the answers

    What role do allosteric enzymes play in metabolic pathways?

    <p>They regulate the pathway by responding to various inhibitors and activators.</p> Signup and view all the answers

    What is the characteristic feature of uncompetitive inhibition?

    <p>The inhibitor binds to the enzyme-substrate complex, preventing product formation.</p> Signup and view all the answers

    Which enzyme is inhibited by cholesterol during feedback inhibition?

    <p>HMG CoA reductase</p> Signup and view all the answers

    What would happen to enzyme activity when too much product is produced in a feedback inhibition system?

    <p>Enzyme activity decreases or stops.</p> Signup and view all the answers

    Which allosteric enzyme is activated by AMP?

    <p>Phosphofructokinase-1</p> Signup and view all the answers

    Which of the following is a common characteristic of allosteric inhibitors?

    <p>They reduce enzyme activity by changing enzyme shape.</p> Signup and view all the answers

    Which of the following statements about feedback inhibition is true?

    <p>It allows for self-regulation in metabolic pathways.</p> Signup and view all the answers

    What is a common property of agents that can denature enzyme activity?

    <p>They alter the pH or temperature.</p> Signup and view all the answers

    Which type of inhibition is characterized by an inhibitor binding only to the enzyme-substrate complex?

    <p>Uncompetitive Inhibition</p> Signup and view all the answers

    Which of the following statements is true regarding allosteric enzymes?

    <p>They can be regulated by both inhibitors and activators.</p> Signup and view all the answers

    What is the main result of noncompetitive inhibition on an enzyme's kinetic parameters?

    <p>Only Vmax decreases while Km remains unchanged.</p> Signup and view all the answers

    Which drug serves as an uncompetitive inhibitor of liver alcohol dehydrogenase?

    <p>Tetramethylene sulfoxide</p> Signup and view all the answers

    Heavy metals such as Ag²+, Hg²+, and Pb²+ are known to act as which type of inhibitors?

    <p>Noncompetitive Inhibitors</p> Signup and view all the answers

    In feedback inhibition, the end product of a metabolic pathway...

    <p>Inhibits the first enzyme in the pathway.</p> Signup and view all the answers

    What is the effect of uncompetitive inhibition on both Vmax and Km?

    <p>Both Vmax and Km decrease.</p> Signup and view all the answers

    Atorvastatin is primarily used to treat which condition?

    <p>High plasma cholesterol levels</p> Signup and view all the answers

    Which enzyme is inhibited by pepstatin?

    <p>Pepsin</p> Signup and view all the answers

    The action of drugs that treat methanol poisoning is an example of which type of inhibition?

    <p>Uncompetitive Inhibition</p> Signup and view all the answers

    Study Notes

    Enzyme Activity Factors

    • Factors affecting enzyme activity include temperature, pH, substrate concentration, enzyme concentration, and metals.

    Regulation of Enzyme Activity

    • Regulation of enzyme activity involves inhibition, allosteric regulation, and feedback inhibition.

    Factors Affecting Enzyme Activity

    • Environmental Conditions: Temperature and pH are key environmental factors affecting enzyme activity.
    • Cofactors and Coenzymes: Certain non-protein molecules, like metal ions, are required for enzyme function and activity.
    • Enzyme Inhibitors: Substances that decrease enzyme activity.

    Temperature

    • Optimum temperature allows the greatest number of molecular collisions.
    • Human enzymes generally function optimally at 35-40°C (body temperature is 37°C.
    • High temperatures can disrupt bonds in the enzyme causing denaturation (loss of 3D shape).
    • Low temperatures reduce molecular movement and decrease collisions between enzyme and substrate, reducing activity.
    • Denaturation also occurs at extreme pH.

    pH

    • Enzymes have optimal pH values; values outside these ranges will disrupt bond interactions that maintain the enzyme's 3D shape, causing denaturation.
    • Pepsin has an optimum pH of 1.4-2 in the stomach while trypsin functions optimally in a range of 7.7-8.

    Substrate Concentration

    • Increasing substrate concentration increases the velocity of enzyme reaction within a limited range.
    • A rectangular hyperbola graph is observed when substrate velocity is plotted against substrate concentration.
    • Three distinct reaction phases are seen on this graph (Initially linear reaction, intermediate curve, and nearly constant reaction rate).

    Enzyme Concentration

    • The rate of a reaction or velocity is directly proportional to enzyme concentration when sufficient substrate is present.
    • Increasing enzyme concentration proportionally increases reaction velocity if sufficient substrate is available.

    Substrate Specificity

    • Enzymes catalyze specific substrate(s).
    • Substrate binds to enzyme's active site.
    • Enzyme-substrate complex formation occurs via hydrogen bonds.
    • Induced fit: Enzyme shape changes to fit substrate tightly.

    Enzyme Catalysis

    • The enzyme does not change during catalysis.
    • The enzyme is ready for the next reaction after the product is released.

    Effect of Activators

    • Some enzymes require inorganic metal ions for optimum activity (e.g., Mn, Zn, Cu, Fe, Co).
    • Metals can combine with the substrate directly or participate in reaction mechanisms, inducing a conformational change in the enzyme.

    Michaelis-Menten Equation

    • An equation describing how reaction velocity varies with substrate concentration.
    • V₀ = Vmax [S] / (Km + [S]), where:
    • V₀ is the initial reaction velocity
    • Vmax is the maximum velocity
    • Km is the Michaelis constant
    • [S] is the substrate concentration

    Michaelis Constant (Km)

    • Km represents the substrate concentration at which the reaction rate is half of the maximum rate (Vmax/2).
    • Km is a measure of the enzyme's affinity for its substrate, Higher Km means a lower affinity. Lower Km indicates a high affinity.

    Enzyme Inhibition

    • Types of Inhibition:

    • Reversible inhibitors bind noncovalently. • Competitive: inhibitor competes with substrate for active site • Noncompetitive: binds to a site other than the active site • Uncompetitive: binds only to the enzyme-substrate complex.

    • Irreversible inhibitors bind covalently to the enzyme

    • Active site directed

    • Suicidal inhibitors

    • Examples of Inhibition: many examples of inhibitors are given across different pages of content.

    Allosteric Enzymes

    • Allosteric enzymes have multiple active sites.
    • Binding of a modulator to a site other than the substrate active site can permanently change the enzyme's conformation.

    Feedback Inhibition

    • The product of a reaction can act as a signal molecule inhibiting the enzyme responsible for its production.
    • This is a system of enzyme regulation via repressor molecules.
    • It's a mechanism for self-regulation, where high product concentrations stop catalysis, and low product concentrations allow catalysis to continue.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Enzyme Activity & Inhibition PDF

    Description

    Explore the various factors that influence enzyme activity, including temperature, pH, substrate concentration, and coenzymes. Understand how these elements affect the efficiency and regulation of enzymes in biological systems.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser