Enzyme Function and Kinetics

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Questions and Answers

An enzyme's specificity for its substrate is primarily determined by what?

  • The sequence of amino acids that make up the enzyme.
  • The three-dimensional structure of the active site and its interactions with the substrate. (correct)
  • The concentration of cofactors available in the cellular environment.
  • The pH and temperature of the surrounding solution.

How does an enzyme affect the equilibrium of a reaction?

  • Alters the equilibrium constant by changing the free energy of the products.
  • Shifts the equilibrium towards reactant regeneration.
  • Does not alter the equilibrium, but increases the rate at which equilibrium is reached. (correct)
  • Shifts the equilibrium towards product formation.

What is the significance of Km in enzyme kinetics?

  • It is the substrate concentration at half the maximum reaction rate, indicating the enzyme's affinity for the substrate. (correct)
  • It indicates the rate of the reverse reaction.
  • It represents the maximum velocity of the enzyme-catalyzed reaction.
  • It is the equilibrium constant for the enzyme-substrate complex formation.

Which type of enzyme inhibitor binds only to the enzyme-substrate complex, affecting both Km and Vmax?

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

How does feedback inhibition regulate enzyme activity in metabolic pathways?

<p>By the end product of a pathway inhibiting an enzyme earlier in the pathway. (A)</p> Signup and view all the answers

In enzyme classification, which class of enzymes catalyzes the transfer of functional groups from one molecule to another?

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

What is the primary role of coenzymes in enzyme-catalyzed reactions?

<p>To assist in the catalytic process by carrying electrons or chemical groups. (C)</p> Signup and view all the answers

How would a competitive inhibitor affect the kinetics of an enzyme-catalyzed reaction?

<p>Increase <code>Km</code> without affecting <code>Vmax</code>. (A)</p> Signup and view all the answers

For an enzyme-catalyzed reaction following Michaelis-Menten kinetics, what does the Lineweaver-Burk plot provide?

<p>A graphical method for determining <code>Km</code> and <code>Vmax</code>. (C)</p> Signup and view all the answers

During an experiment, it is observed that increasing the temperature beyond a certain point causes a significant decrease in enzyme activity. What is the most likely explanation for this phenomenon?

<p>The enzyme is undergoing denaturation, leading to a loss of its functional structure. (A)</p> Signup and view all the answers

Flashcards

Enzymes

Biological catalysts, typically proteins, that speed up chemical reactions in living organisms by lowering activation energy.

Active Site

The specific region of an enzyme where the substrate binds and catalysis occurs.

Cofactors/Coenzymes

Non-protein molecules that assist enzymes in catalyzing reactions, can be metal ions or organic molecules.

Activation Energy (Ea)

The energy required to reach the transition state in a chemical reaction.

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Vmax

The maximum reaction rate when the enzyme is saturated with substrate.

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Km (Michaelis Constant)

Substrate concentration at which the reaction rate is half of Vmax, indicates enzyme's affinity for its substrate.

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Enzyme Inhibitors

Substances that reduce enzyme activity, can be reversible or irreversible.

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Competitive Inhibitors

Binds to the active site, preventing substrate binding, increases Km but does not affect Vmax.

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Non-Competitive Inhibitors

Binds to a site other than the active site, altering enzyme conformation and reducing activity, decreases Vmax but does not affect Km.

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Allosteric Regulation

Modulators bind to a site other than the active site (allosteric site), altering the enzyme's conformation and activity.

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