Enzymes

• Define Enzymes

  Biological catalysts
• What are the main functions of biological catalysts

  
  

  • Regulate the flow of molecules through all metabolic pathways
  • Build and break structures of cells
  • Break down invading pathogens and parasites
• Main requirements of Enzymes

  • Increase reaction rates
  • Unchanged after the reaction
  • Majority are proteins
• What is the half-life of an enzyme

  
  

  The time taken for half of the reactants to be converted to products.
• What is the suffix for enzymes

  -ase
• Describe enzyme commission classification method

  • 4 Digits
  • First = Bulk descriptor
  • Second = Bonds broken
  • Third = Groups removed
  • Fourth = Substrate descriptor
• What does Katal (kat)measure

  The amount of an enzyme that converts 1 mol of substrate per second under standard assay conditions
• What does International activity unit (U)measure

  The amount of enzyme that will catalyse the transformation of 1 micromole of the substrate per minute under standard assay conditions
• What does Keq stand for.

  The equilibrium rate constant.
• Activation energy (EA)

  Initial input of energy required to kick start a reaction
• Transition state

  Unstable point at the summit of the energy profile diagram
• How do Enzymes increase reaction rates

  By reducing the activation energy (EA) the transition state can be reached more easily. ,
• Describe the Lock-and-key hypothesis

  Formation of the enzyme-substrate complex conversion to the enzyme-product complex.
• Do Enzymes change the overall free energy change (ΔG) of a reaction

  No
• Equation for Equilibrium rate constant.

  Keq = Kfor / Krev
• What is an exergonic reaction

  Releases energy. If the Activation energy is overcome it may occur spontaneously.
• What is an endogonic reaction

  Required input of energy.
• Does breaking bonds require energy

  Yes
• Does making bonds require energy

  No
• What is the equivalent for Activation energy

  Gibbs free energy of activation.
• What does the Double dagger after Delat-G signify

  The reaction involves a transition state.
• What do energy profile diagrams show

  Change in free energy as the reaction progresses.
• What does Delta-G mean

  • Total reaction change in free energy
• How do you calculate Delta-G

  Free energy of Products - Reactants
• What is Delta-G double dagger

  Change in Gibbs free energy of activation
• How do you calculate Delta-G double dagger

  Difference between free energy of transition state and reactants.
• Define free energy

  Energy in the molecular bonds.
• Why is the lock and key hypothesis wrong

  If the enzyme was complimentary to the substrate the complex would be more stable than the substrate and so require more energy to break.
• Describe the theory for an enzyme being complimentary to the transition state

  1. Substrate binds to active site weakly
  2. Transition state formation releases energy
  3. Product formed
• What enzyme are jeans treated with to achieve the stone-washed effect

  Cellulases
• What is this

  This is a reaction profile.

  A) Transition state

  B) EA

  C) EA no enzyme

  D) Change in free energy