L7-9 quiz

• metal ions in enzymes functions:

  • general acid base catalysis
  • oxidation-reduction reactions
  • assist in substrate binding
• enzyme inhibitor useful as a chemotherapy drug:

  methotrexate
• induced fit model of enzyme-substrate interaction helps to explain how

  enzymes lower the activation energy
• enzyme and substrate change shape following binding to move the substrate closer to the transition state for the reaction in the


  induced fit model
• covalent catalysis


  involves covalent modification of enzyme active site amino acids during catalysis
• enzymes bind more strongly to the transition state of the reaction than to the substrate
• enzymes form multiple non-covalent interactions with their substrates
• enzymes provide energy for reactions by placing strain on the covalent bonds present in substrate molecules
• the active site is flexible to promote the specific substrate binding
• the rate of an enzyme catalysed reaction is proportional to enzyme concentration
• the rate of an enzyme catalysed reaction is proportional to substrate concentration only at low substrate concentration
• rate of an enzyme catalysed reaction is dependent on conditions such as


  pH and temperature
• Michaelis constant (Km) is measured in units of

  molarity (concentration)
• Michaelis constant (Km) represents the substrate concentration at which the reaction rate is

  half maximal
• Michaelis constant (Km) represents the substrate concentration at which half the active sites are

  occupied
• Michaelis constant (Km) approximates the affinity of the enzyme for the 


  substrate
• aspirin inhibits the enzyme cyclooxygenase by irreversible inhibition
• the number of substrate molecules converted into product per unit time when the enzyme is fully saturated with substrate is known as the turnover number
• the turnover number can be used to compare the efficiencies of 2 unrelated enzymes in relation to their cognate substrates