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4.3 Mechanisms β Test 1
Q1. An aspartate ammonia lyase would catalyze which one of the following reactions?β Deamination
Q2. Which one of the following enzyme mechanisms does not involve covalent catalysis?β HIV protease
Q3. Which of the following amino acid side chains can act as a nucleophile in enzyme catalysis?β Histidine
Q4. Enzymes lower activation energy by bringing reactants close together in the right orientation. The reacting species in an enzymatic reaction:β Behaves like an intramolecular reaction rather than inter-molecular
Q5. Abzymes are produced with the help of:β Transition state analogues
Q6. Which three amino acids are present in the Tc AChE catalytic triad?β Serine 200, Histidine 440, Glutamate 327
Q7. An acid phosphatase acts upon (A) and a cathepsin acts upon (B). What are A and B?β Phosphomonoesters and proteins
Q8. Which of the following enzyme reactions is termed an acyl group transfer reaction?β Chymotrypsin
Q9. βBoth substrates A and B must be present at the active site simultaneouslyβ is a feature of:β Single displacement (sequential) reactions
Q10. Which statements are true for enzymes and other catalysts? They:β Both decrease the activation energy
Q11. The function of enzymes and other catalysts is to:β Decrease the activation energy
Q12. The function of enzymes and other catalysts is to (repeat):β Decrease the activation energy
Q13. In serine proteases, the nucleophile is activated primarily by:β Histidine
Q14. The Lock and Key hypothesis of enzyme action was given by:β Emil Fischer
Q15. In a reaction at equilibrium in solution, what happens if an enzyme is added?β The equilibrium of the reaction will not change
Q16. Which is CORRECT for enzyme-catalysed reactions?β Affect neither
Q17. Which statement about the nature of enzyme catalysis is correct?β The rate of forming the transition-state intermediate determines the overall reaction rate
Q18. Which is true for an enzyme-catalysed reaction?β Enzymes can couple energetically unfavorable reactions to favorable ones
Q19. Which is true for enzyme catalysis? Enzymes:β Do not alter the equilibrium of the reaction
4.3 Mechanisms β Test 2
Q20. Which is true for an enzyme-catalysed reaction? Enzymes:β Do not alter the equilibrium of the reaction
Q21. Identify the statement NOT applicable to an enzyme-catalysed reaction.β Enzymes do not accelerate the rate of the reverse reaction
Q22. Identify the statement NOT applicable to an enzyme-catalysed reaction.β Enzymes do not accelerate the reverse reaction
Q23. Which of the following is true about enzymes?β Catalytic efficiency can be predicted from its kinetic studies
Q24. By which mechanism does an enzyme increase the rate of a reaction?β It lowers the activation energy of the reaction
Q25. An enzyme acts by:β Reducing the energy of activation
Q26. Which best describes induced fit?β Binding of substrate alters the shape of the binding site
Q27. Fischer's Lock and Key model implies that:β The active site is complementary in shape to the substrate
Q28. The enzyme present in tears is:β Lysozyme
Q29. During synthesis of a hexa-NAG, the glycosidic O between sugars D and E was labelled with ΒΉβΈO. After lysozyme hydrolysis, the isotope appears in the:β C-4 hydroxyl of di-NAG (residues E-F)
Q30. Which amino acid can act as a nucleophile in enzyme catalysis?β Serine
Q31. The catalytic serine in a serine protease behaves as a:β Nucleophile
Q32. Conserved Ser, His and Asp form the catalytic centre of serine proteases. The role of histidine is:β Proton transfer
Q33. The catalytic serine in a serine protease behaves as a (repeat):β Nucleophile
Q34. Conserved Ser, His and Asp form the catalytic centre of serine proteases. Role of the histidine residue:β Proton transfer
Q35. Serine proteases are named so because:β The catalytic mechanism is initiated by one of the serines of the enzyme
Q36. An enzyme that catalyzes stereospecific isomerisation:β Alanine racemase
Q37. Match the protease with its catalytic mechanism:β i-c, ii-a, iii-b, iv-d