Biochemistry 3: Enzymes (Part 2)

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Questions and Answers

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

  • Competitive inhibitor
  • Uncompetitive inhibitor
  • Non-competitive inhibitor (correct)
  • Irreversible inhibitor

What happens to the observed KM and Vmax in non-competitive inhibition?

  • Both KM and Vmax are reduced (correct)
  • KM is decreased, Vmax is increased
  • KM is unaffected, Vmax is decreased
  • KM is increased, Vmax is decreased

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

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

What is the effect of a non-competitive inhibitor on the enzyme's activity?

<p>It converts the enzyme to an inactive state (C)</p> Signup and view all the answers

Which type of inhibitor binds to the enzyme-substrate complex?

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

What is the effect of an inhibitor on the Lineweaver-Burk plot in non-competitive inhibition?

<p>It decreases the slope and increases the intercept (C)</p> Signup and view all the answers

What is the characteristic of competitive inhibition in terms of substrate concentration?

<p>Inhibition is overcome at high substrate concentration (A)</p> Signup and view all the answers

What is the main difference between competitive and non-competitive inhibitors?

<p>Competitive inhibitors bind to the active site, while non-competitive inhibitors bind to an allosteric site. (B)</p> Signup and view all the answers

What type of inhibitor affects the enzyme's activity by binding to the active site?

<p>Competitive inhibitor (D)</p> Signup and view all the answers

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

<p>Km increases, Vmax remains the same. (A)</p> Signup and view all the answers

What is the purpose of product inhibition in enzyme-catalyzed reactions?

<p>To slow down the reaction once enough product is made. (B)</p> Signup and view all the answers

What is the definition of Km?

<p>The substrate concentration that produces half maximal velocity. (A)</p> Signup and view all the answers

What is the effect of increasing substrate concentration on competitive inhibition?

<p>It overcomes the inhibition. (B)</p> Signup and view all the answers

What is the equation that describes the effect of a competitive inhibitor on the enzyme activity?

<p>v0 = Vmax/(KM + [S] + Ki[I]). (B)</p> Signup and view all the answers

What is the purpose of enzymes in biological systems?

<p>To increase the rate of reactions. (C)</p> Signup and view all the answers

What is an example of an enzyme that is inhibited by its product?

<p>Galactase. (A)</p> Signup and view all the answers

What is the name of the enzyme composed of two different protein subunits?

<p>LDH (C)</p> Signup and view all the answers

What is the location of the HHMM (LDH3) isozyme?

<p>Unknown location (B)</p> Signup and view all the answers

Which isozyme is increased in leukemia?

<p>All five isozymes (A)</p> Signup and view all the answers

What is the biomedical importance of enzymes?

<p>They help in diagnosing diseases (B)</p> Signup and view all the answers

What is the principle of ELISA?

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

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

<p>The amount of antibody is proportional to the amount of antigen (A)</p> Signup and view all the answers

What is measured in the kinetics of an enzyme?

<p>The rate of substrate conversion (B)</p> Signup and view all the answers

What is the effect of the inhibitor on the kinetics of an enzyme?

<p>It decreases the Vmax (D)</p> Signup and view all the answers

What is the binding site of allosteric effectors?

<p>A site different from the substrate binding pocket (A)</p> Signup and view all the answers

What is the effect of allosteric effectors on enzyme activity?

<p>Increase enzyme activity (C)</p> Signup and view all the answers

What is the result of K-type regulation?

<p>Decrease in KM (B)</p> Signup and view all the answers

What is the result of V-type regulation?

<p>Increase in Vmax (D)</p> Signup and view all the answers

What is the characteristic of isoenzymes?

<p>They catalyze the same reaction but differ in their physical properties (C)</p> Signup and view all the answers

How do isoenzymes differ from each other?

<p>They differ in their amino acid sequence (D)</p> Signup and view all the answers

What is the characteristic of creatine kinase isoenzymes?

<p>They are composed of two polypeptides (B and M subunits) (C)</p> Signup and view all the answers

What is the purpose of electrophoresis in isoenzyme analysis?

<p>To separate isoenzymes based on their physical properties (D)</p> Signup and view all the answers

What is the value of Km in the presence of the inhibitor?

<p>31 μM (D)</p> Signup and view all the answers

What is the type of inhibition depicted in the graph?

<p>Competitive (C)</p> Signup and view all the answers

What is the purpose of the Lineweaver-Burk method?

<p>To linearize the non-linear Michaelis-Menten equation (D)</p> Signup and view all the answers

How is enzyme activity regulated?

<p>By gene expression, substrate and cosubstrate availability, pH, temperature, and allosteric regulators (D)</p> Signup and view all the answers

What is the characteristic of multimeric enzymes?

<p>They show cooperativity (A)</p> Signup and view all the answers

What is the name of the model that accounts for enzyme kinetics?

<p>Michaelis-Menten model (C)</p> Signup and view all the answers

What is the unit of Vmax?

<p>μM/min (A)</p> Signup and view all the answers

What is the effect of a competitive inhibitor on the enzyme kinetics?

<p>It increases the Km value (B)</p> Signup and view all the answers

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