WK 1: Enzymes as Drug Targets
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Questions and Answers

What is the primary role of enzymes in biochemical reactions?

  • To synthesize ATP
  • To regulate gene expression
  • To repair damaged DNA
  • To catalyze biochemical reactions (correct)

What is the result of phosphorylation of an enzyme by a protein kinase?

  • Inactivation of the enzyme
  • Denaturation of the enzyme
  • Allosteric inhibition of the enzyme
  • Activation of the enzyme (correct)

What is the characteristic of a reversible inhibitor?

  • It forms a covalent bond with the enzyme
  • It is irreversible and cannot be removed
  • It is a competitive inhibitor only
  • It is similar in structure to the substrate or product (correct)

What is the purpose of binding interactions between an enzyme and its substrate?

<p>To hold the substrate sufficiently long for the reaction to occur (B)</p> Signup and view all the answers

What is the effect of increasing substrate concentration on a reversible inhibitor?

<p>It reverses the inhibition of the enzyme (B)</p> Signup and view all the answers

What is the result of designing molecules with stronger binding interactions to an enzyme?

<p>Inhibition of the enzyme (C)</p> Signup and view all the answers

What is the primary role of enzymes in the body?

<p>To act as the body's catalysts (A)</p> Signup and view all the answers

What is the effect of an enzyme on the activation energy of a reaction?

<p>It decreases the activation energy (A)</p> Signup and view all the answers

What is the role of lactate dehydrogenase (LDH) in the reaction shown?

<p>It acts as a catalyst (A)</p> Signup and view all the answers

What is the significance of enzymes in metabolism and disease?

<p>They play a crucial role in both metabolic pathways and can be used as biomarkers of organ injury (C)</p> Signup and view all the answers

What is the effect of an enzyme on the overall free energy change (ΔG) of a reaction?

<p>It has no effect on ΔG (B)</p> Signup and view all the answers

What is the term for the molecules that bind to enzymes and increase their activity?

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

What is the primary function of enzymes in biochemical reactions?

<p>To catalyse biochemical reactions (B)</p> Signup and view all the answers

What is the role of the oxyanion hole in the catalysis mechanism of chymotrypsin?

<p>To lower the activation energy of the reaction (C)</p> Signup and view all the answers

What is the outcome of designing molecules with stronger binding interactions with an enzyme?

<p>Enzyme inhibition (B)</p> Signup and view all the answers

What is the purpose of the binding interactions between the enzyme and substrate?

<p>To hold the substrate sufficiently long for the reaction to occur (A)</p> Signup and view all the answers

What is the role of enzymes in metabolism and disease?

<p>To play a crucial role in metabolism and can be used as biomarkers of injury to specific organs (B)</p> Signup and view all the answers

What is the outcome of enzyme catalysis?

<p>Formation of product (B)</p> Signup and view all the answers

What is the primary function of an enzyme's active site?

<p>To bind reactants and position them correctly (A)</p> Signup and view all the answers

What occurs during the induced fit process of substrate binding?

<p>The shape of the enzyme changes to fit the substrate (C)</p> Signup and view all the answers

What type of bond is formed between the functional groups in the substrate and the active site during substrate binding?

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

What is the role of the enzyme in a biochemical reaction?

<p>To catalyse the reaction (C)</p> Signup and view all the answers

What is the result of the enzyme's catalytic mechanism?

<p>The reaction rate is increased (A)</p> Signup and view all the answers

What is the purpose of the enzyme's active site in terms of reactant binding?

<p>To position reactants correctly for reaction (C)</p> Signup and view all the answers

What is the role of histidine in the catalytic mechanism of chymotrypsin?

<p>Acting as an acid/base catalyst (D)</p> Signup and view all the answers

What is the role of aspartate in the catalytic mechanism of chymotrypsin?

<p>Orientating histidine for catalysis (D)</p> Signup and view all the answers

What is the function of serine in the catalytic mechanism of chymotrypsin?

<p>Acting as a nucleophile (D)</p> Signup and view all the answers

What is the outcome of the catalytic mechanism of chymotrypsin?

<p>Hydrolysis of a peptide bond (A)</p> Signup and view all the answers

What is the functional significance of the catalytic triad in chymotrypsin?

<p>Improving catalytic efficiency (B)</p> Signup and view all the answers

What is the biochemical significance of chymotrypsin?

<p>Digestion of proteins in the small intestine (C)</p> Signup and view all the answers

Flashcards

What is the primary role of enzymes in biochemical reactions?

Enzymes are biological catalysts that speed up biochemical reactions without being consumed in the process.

What is the result of phosphorylation of an enzyme by a protein kinase?

Phosphorylation by a protein kinase activates the enzyme by changing its shape and allowing it to bind to its substrate.

What is the characteristic of a reversible inhibitor?

Reversible inhibitors bind to the enzyme in a way that can be reversed, typically by increasing the substrate concentration.

What is the purpose of binding interactions between an enzyme and its substrate?

Binding interactions between an enzyme and its substrate hold the substrate in the active site long enough for the reaction to occur.

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What is the effect of increasing substrate concentration on a reversible inhibitor?

Increasing substrate concentration can overcome the inhibition by pushing the equilibrium towards the formation of the enzyme-substrate complex.

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What is the result of designing molecules with stronger binding interactions to an enzyme?

Designing molecules with stronger binding interactions with an enzyme can inhibit its activity by preventing the substrate from binding.

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What is the primary role of enzymes in the body?

Enzymes act as catalysts within the body, accelerating biochemical reactions necessary for life.

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What is the effect of an enzyme on the activation energy of a reaction?

Enzymes lower the activation energy of a reaction, making it easier for the reaction to proceed.

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What is the role of lactate dehydrogenase (LDH) in the reaction shown?

Lactate dehydrogenase (LDH) is an enzyme that catalyzes the interconversion of lactate and pyruvate, a key step in energy metabolism.

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What is the significance of enzymes in metabolism and disease?

Enzymes are crucial for metabolic pathways, allowing for the synthesis and breakdown of molecules needed for cellular processes. Levels of certain enzymes can also be indicative of organ damage, making them useful biomarkers.

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What is the effect of an enzyme on the overall free energy change (ΔG) of a reaction?

Enzymes do not alter the overall free energy change (ΔG) of a reaction. They only accelerate the rate at which the reaction proceeds.

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What is the term for the molecules that bind to enzymes and increase their activity?

Cofactors are non-protein molecules that bind to enzymes and are essential for their activity. They can be metal ions or organic molecules.

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What is the primary function of enzymes in biochemical reactions?

Enzymes are biological catalysts that speed up biochemical reactions without being consumed in the process.

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What is the role of the oxyanion hole in the catalysis mechanism of chymotrypsin?

The oxyanion hole in chymotrypsin helps to stabilize the negatively charged transition state during peptide bond hydrolysis, thereby lowering the activation energy.

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What is the outcome of designing molecules with stronger binding interactions with an enzyme?

Designing molecules with stronger binding interactions with an enzyme can block the active site, preventing the substrate from binding and inhibiting the enzyme's activity.

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What is the purpose of the binding interactions between the enzyme and substrate?

Binding interactions between the enzyme and substrate hold the substrate in the active site long enough for the reaction to occur.

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What is the role of enzymes in metabolism and disease?

Enzymes are crucial for metabolism, allowing for the synthesis and breakdown of molecules needed for cellular processes. Levels of certain enzymes can also be indicative of organ damage, making them useful biomarkers.

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What is the outcome of enzyme catalysis?

Enzyme catalysis results in the formation of a product from the substrate through a specific chemical reaction.

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What is the primary function of an enzyme's active site?

The active site of an enzyme serves as the binding site for reactants, positioning them correctly for a chemical reaction to occur.

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What occurs during the induced fit process of substrate binding?

The induced fit process of substrate binding involves a conformational change in the enzyme's active site to better accommodate the substrate, leading to optimal binding.

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What type of bond is formed between the functional groups in the substrate and the active site during substrate binding?

Intermolecular bonds, such as hydrogen bonds, ionic interactions, and van der Waals forces, are formed between the functional groups in the substrate and the active site during substrate binding.

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What is the role of the enzyme in a biochemical reaction?

Enzymes act as catalysts, accelerating the rate of a biochemical reaction by lowering the activation energy barrier.

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What is the result of the enzyme's catalytic mechanism?

The catalytic mechanism of an enzyme increases the rate of the reaction by lowering the activation energy and facilitating the formation of the transition state.

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What is the purpose of the enzyme's active site in terms of reactant binding?

The active site of an enzyme binds reactants in a specific orientation that favors the correct chemical interactions for the reaction to occur.

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What is the role of histidine in the catalytic mechanism of chymotrypsin?

Histidine in chymotrypsin acts as a general acid/base catalyst, alternating between protonated and deprotonated states to facilitate the transfer of protons during the catalytic cycle.

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What is the role of aspartate in the catalytic mechanism of chymotrypsin?

Aspartate in chymotrypsin helps to orientate histidine for optimal catalytic activity by forming a hydrogen bond with it, ensuring proper positioning.

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What is the function of serine in the catalytic mechanism of chymotrypsin?

Serine in chymotrypsin acts as a nucleophile, attacking the carbonyl carbon of the peptide bond during the initial step of the catalytic mechanism.

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What is the outcome of the catalytic mechanism of chymotrypsin?

The catalytic mechanism of chymotrypsin involves a series of steps, including nucleophilic attack by serine, formation of a tetrahedral intermediate, and hydrolysis of the peptide bond, resulting in the cleavage of the peptide chain.

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What is the functional significance of the catalytic triad in chymotrypsin?

The catalytic triad, consisting of serine, histidine, and aspartate, works together to increase the catalytic efficiency of chymotrypsin by optimizing the positioning and reactivity of the catalytic residues.

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What is the biochemical significance of chymotrypsin?

Chymotrypsin is a digestive enzyme that breaks down proteins into smaller peptides in the small intestine, facilitating their absorption into the bloodstream.

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