enzymes

• Activation energy


  The amount of energy needed for a reaction to happen
• Active site


  A specific region on an enzyme where the substrate binds and the reaction takes place
• Amylase


  An enzyme that catalyses the extracellular breakdown of starch
• Catalase


  An enzyme that catalyses the intracellular breakdown of hydrogen peroxide into oxygen and water
• Co-enzyme


  A type of co-factor that is bound loosely to an enzyme with weak interactions
• Co-factors


  A non-protein molecule that is needed for the effective functioning of an enzyme
• Competitive inhibitor


  A molecule which binds to the active site of an enzyme and prevents the substrate from binding
• Cyanide (CN-)


  A metabolic poison which acts as an irreversible inhibitor of cytochrome oxidase and hence preventing respiration
• End-product inhibition


  A method of enzyme inhibition where the product of an enzyme controlled reaction can bind to the enzyme and prevent it from working
• Enzyme


  A biological catalyst used to speed up the rate of biochemical reactions without being used up or permanently altered
• Enzyme product complex


  The temporary complex formed after the enzyme has catalysed the reaction but before the products have left the active site of the enzyme
• Enzyme substrate complex


  The temporary complex formed when the substrate binds to the active site of the enzyme
• Extracellular reaction


  A reaction that occurs outside of cells
• Inactive precursor


  An inactive form of an enzyme that cannot carry out its function until it is activated
• Induced fit hypothesis


  A model of enzyme action that describes how once a specific substrate binds to the active site, the enzyme undergoes subtle conformational changes to fit the substrate better
• Intracellular reaction


  A reaction that occurs within cells
• Lock and key hypothesis


  A model of enzyme action that describes how the enzyme will only fit a substrate that has the correct complementary shape to the active site
• Metabolism


  The sum of all the chemical reactions taking place in a cell
• Non-competitive inhibitor


  An inhibitor which binds to a different part of an enzyme known as the allosteric site and prevents the enzyme from functioning
• Prosthetic group


  A type of cofactor that is bound tightly to an enzyme with strong interactions
• Substrate specificity


  The ability of an enzyme to catalyse only a specific reaction or set of reactions which have substrates complementary to the active site of the enzyme
• Temperature co-efficient (Q10)


  A method of calculating an increase in reaction rate after a 10oc temperature increase - calculated using:

  • Q10 = (RoR at high temp) / (Ror at low temp)
• Trypsin


  An enzyme that catalyses the extracellular breakdown of proteins