Enzyme kinetics

• What is Enzyme kinetics

  Describing how an enzyme or inhibitor works under different conditions. These include pH, substrate and enzyme concentrations, temperature.
• What does an effective inhibitor do to the reaction rate

  Slows down the reaction
• What is the relashionship between substrate and rate without an enzyme

  Directly proportional
• What shape is the rate graph with an enzyme

  Rectangular hyperbola
• What happens to the rate once the substrate concentration is high

  The rate becomes independent of substrate concentration and dependent on the formation of the enzyme-substrate complex.
• What happens at Vmax.

  The active site is saturated
• Define Vmax

  The maximum possible rate of the reaction at that particular enzyme concentration
• Define Km

  The substrate concentration at half of Vmax.
• What is the requirement to reach Vmax

  Infinate substrate
• Assumptions and limitations of Michaelis-Menten kinetics

  • Reaction is a single substrate reaction
  • K2 is negligible
• Which way does the curve shift if enzyme B has higher affinity than A?

  To the left as Km is lower.
• What is the name for a double reciprocal plot

  Lineweaver-Burk plot
• What is the equation for rate from the hyperbola graph

  V =(Vmax * [S]) / (Km + [S])
• What does a low Km indicate

  A high affinity for the enzyme
• What is the unit for Velocity in enzyme reactions

  nmol / min
• What is the unit for concentration in enzyme reactions


  nmol / liter
• What is Km independant of

  The enzyme and substrate concentrations
• What is Vmax dependant and independant on

  Independant of substrate concentration. Dependent on enzyme concentration.
• Describe the Michaelis-Menten assumption that the reaction involves 1 substrate

  Substrates can have different binding sites or impact the binding of another.
• What is the assumption in this equation?

  That K2 cannot be reversed.

  It assumes that there is no reverse catalysis or product inhibition.

  A) K1

  B) K2

  C) K-1

  
• How is a Michaelis-Menten graph created

  • Measure product formation over time at different substrate concentrations
  • Plot Initial velocity [Vo]
• What is the equation for turnover number

  Kcat = Vmax / [Et]. Where Et = [E] + [ES].
• What is used to compare the efficiency of unrelated enzymes

  Kcat.
• What are the features of the Lineweaver-Bruk plot

  When you plot the reciprocal values for rate and concentration, it produces a linear graph.
• What are the two intercepts of a Lineweaver-Burk plot

  -1/Km. And 1/Vmax.
• What is the relashionship between [S] and rate at low concentration of [S]

  Proportional
• What is the relashionship between rate and [S]

  Proportional