Biochemistry 3 Lecture 5: Enzymes (Part 2)
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Questions and Answers

What is the term for the substrate concentration that produces half maximal velocity?

  • Km (correct)
  • Vm
  • Ki
  • Vmax

    • What type of enzyme inhibition can be overcome by high substrate concentration?

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

    • What is the effect of a competitive inhibitor on the Kmapp and Vmax of an enzyme?

  • Kmapp increased, Vmax decreased
  • Kmapp decreased, Vmax increased
  • Kmapp increased, Vmax unaltered (correct)
  • Kmapp decreased, Vmax decreased

    • What is the term for the rate of the reaction when all the enzymes are saturated with substrate?

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

    What is the purpose of product inhibition in enzyme regulation?

    <p>To slow down enzyme activity once enough product is made</p> Signup and view all the answers

    What type of inhibition occurs when the product of an enzyme-catalyzed reaction binds to the active site and displaces new substrate?

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

    What is the effect of a competitive inhibitor on the enzyme's ability to attain Vmax?

    <p>The enzyme can attain Vmax only if the inhibitor is removed</p> Signup and view all the answers

    What is the term for the inhibitor that binds to the active site and prevents product formation?

    <p>Non-competitive inhibitor</p> Signup and view all the answers

    Where do allosteric effectors bind?

    <p>To a site different from the substrate binding pocket</p> Signup and view all the answers

    What is the effect of allosteric effectors on enzyme activity?

    <p>They increase enzyme activity</p> Signup and view all the answers

    What happens to KM in K-type regulation?

    <p>It decreases</p> Signup and view all the answers

    What type of inhibitor binds to an allosteric site on the protein?

    <p>Non-competitive inhibitor</p> Signup and view all the answers

    What happens to Vmax in V-type regulation?

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

    What is the effect of a non-competitive inhibitor on the Km and Vmax of an enzyme?

    <p>Km unaltered, Vmax apparent decreased</p> Signup and view all the answers

    What are isoenzymes?

    <p>Enzymes that catalyze the same reaction but differ in their physical properties</p> Signup and view all the answers

    What is the difference between isoenzymes?

    <p>Their amino acid sequence</p> Signup and view all the answers

    What type of inhibition occurs when an inhibitor binds covalently to a residue within the active site of the enzyme?

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

    How can isoenzymes be separated from each other?

    <p>By electrophoresis</p> Signup and view all the answers

    What is the effect of an uncompetitive inhibitor on the Km and Vmax of an enzyme?

    <p>Both Km and Vmax are reduced</p> Signup and view all the answers

    What is the characteristic of competitive inhibition in Lineweaver-Burk representation?

    <p>Only Km is affected</p> Signup and view all the answers

    What is the composition of creatine kinase isoenzymes?

    <p>A dimer composed of two different polypeptides</p> Signup and view all the answers

    What type of inhibitor binds only to the enzyme-substrate complex?

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

    What is the effect of a non-competitive inhibitor on the enzyme activity at high substrate concentration?

    <p>The enzyme activity is decreased</p> Signup and view all the answers

    What is the characteristic of non-competitive inhibition in Lineweaver-Burk representation?

    <p>Vmax is reduced, Km is unaltered</p> Signup and view all the answers

    What happens to enzyme activity when an inhibitor is irreversibly bound?

    <p>It is abolished</p> Signup and view all the answers

    What type of regulation is not suitable for rapid adaptation?

    <p>Enzyme expression</p> Signup and view all the answers

    What is the effect of a 10 °C temperature rise on the rate of enzyme-catalyzed reactions?

    <p>It doubles the reaction rate</p> Signup and view all the answers

    What is the exception to the general rule of enzyme denaturation above 50 °C?

    <p>Enzymes from thermophilic bacteria</p> Signup and view all the answers

    What is the effect of pH on enzyme activity?

    <p>Each enzyme has a specific pH optimum</p> Signup and view all the answers

    How can a change in pH affect enzyme activity?

    <p>It can affect the binding of substrate, actual catalysis, or the global conformation of the protein</p> Signup and view all the answers

    What is the result of an effector binding to the substrate site of an enzyme?

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

    What type of regulation involves the binding of molecules to an enzyme to alter its activity?

    <p>Allosteric regulation</p> Signup and view all the answers

    What is the composition of Lactate Dehydrogenase (LDH) enzyme?

    <p>A combination of two different protein subunits</p> Signup and view all the answers

    What is the function of Lactate Dehydrogenase (LDH) isozymes in diagnosis?

    <p>To diagnose diseases</p> Signup and view all the answers

    What is the role of LDH isozyme in diagnosing myocardial infarction?

    <p>To diagnose myocardial infarction</p> Signup and view all the answers

    What is the principle of ELISA (enzyme-linked immunosorbant assay)?

    <p>Linking an enzyme to an antibody</p> Signup and view all the answers

    What is the role of the substrate in ELISA?

    <p>To allow for color development</p> Signup and view all the answers

    What is the significance of Vmax and KM in enzyme kinetics?

    <p>They are used to measure the rate of enzyme reaction</p> Signup and view all the answers

    What is the purpose of adding an inhibitor in enzyme kinetics?

    <p>To decrease the rate of enzyme reaction</p> Signup and view all the answers

    What is the result of an immunological reaction between the antigen and the prepared antibody in ELISA?

    <p>The amount of antibody bound to the antigen is proportional to the amount of antigen present</p> Signup and view all the answers

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