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  • Question
  • The proteolysis rate enhancement by chymotrypsin (~1010 folds) corresponds to a reduction in activation energy of about


  • Options
  • A. 40 kJ/mol
  • B. 49 kJ/mol
  • C. 58 kJ/mol
  • D. 88 kJ/mol

  • Correct Answer
  • 58 kJ/mol 


  • Enzymes problems


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    • 1. Which of the following statements about enzymes or their function is true?

    • Options
    • A. Enzymes do not alter the overall change in free energy for a reaction
    • B. Enzymes are proteins whose three-dimensional form is key to their function
    • C. Enzymes speed up reactions by lowering activation energy
    • D. All of the above
    • Discuss
    • 2. Before they can react, many molecules need to be destabilized. This state is typically achieved through

    • Options
    • A. changing the three-dimensional shape of the molecule
    • B. oxidizing the molecules by removing electrons
    • C. changing the reaction from a biosynthetic to a catabolic pathway
    • D. the input of a small amount of activation energy
    • Discuss
    • 3. In the enzyme-catalyzed reaction shown below, what will be the effect on substances A, B, C, and D of inactivating the enzyme labeled E2?

      A ---(E1)---> B ---(E2)---> C ---(E3)--->


    • Options
    • A. A, B, C, and D will all still be produced
    • B. A, B, and C will still be produced, but not D
    • C. A and B will still be produced, but not C or D
    • D. A will still be produced, but not B, C, or D
    • Discuss
    • 4. Enzyme-driven metabolic pathways can be made more efficient by

    • Options
    • A. concentrating enzymes within specific cellular compartments
    • B. grouping enzymes into free-floating, multienzyme complexes
    • C. fixing enzymes into membranes so that they are adjacent to each other
    • D. All of the above
    • Discuss
    • 5. The nucleophile in serine proteases is

    • Options
    • A. Serine
    • B. water
    • C. both (a) and (b)
    • D. Asparagine
    • Discuss
    • 6. Common feature in all serine proteases is a

    • Options
    • A. hydrophobic specificity pocket
    • B. hydrophilic specificity pocket
    • C. cluster of reactive serine residues
    • D. single reactive serine residue
    • Discuss
    • 7. What is the specificity of the Clostripain protease?

    • Options
    • A. It cleave after Arg residues
    • B. It cleave after His residues
    • C. It cleave after Lys residues
    • D. None of the above
    • Discuss
    • 8. Tryprotophan synthetase of E.coli, a typical bifunctional oligomeric enzyme consist of

    • Options
    • A. a protein designated A
    • B. two proteins designated A and B
    • C. a protein A and one-subunit a
    • D. a protein designated B
    • Discuss
    • 9. Which of the following is false statement with regard to comparison between Serine and HIV proteases?

    • Options
    • A. Both use nucleophilic attack to hydrolyze the peptide bond
    • B. Both require water to complete the catalytic cycle
    • C. Both forms an acyl-enzyme intermediate
    • D. Both show specificity for certain amino acid sequences
    • Discuss
    • 10. How is the enzyme COX-1 important in human health?

    • Options
    • A. It helps to transport carbon dioxide in the blood
    • B. It is critical for the biosynthesis of DNA
    • C. It is a chemical derivative of aspirin
    • D. It catalyzes the production of hormones that maintain the stomach lining
    • Discuss


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