Enzymes

• Lysozyme-an enzyme found in tears or saliva that damages cell walls of bacteria
• Metabolism- the sum of all the chemical reactions in a cell or organism
• Activation energy - The minimum amount of energy needed for a reaction to happen.
• Active site - A specific region on an enzyme where the substrate binds and the reaction
• Buffer - A molecule that maintains a constant pH in a solution by neutralising small volumes of added acid or base.
• Catalysis - Increasing the rate of a chemical reaction via the reduction in activation energy.
• Competitive inhibitors - A molecule which binds to the active site of an enzyme and prevents the substrate from binding.
• •Denaturation - Upon exposure to high temperatures or extremes of pH, the permanent change in the tertiary structure of an enzyme and the shape of its active site, preventing it from carrying out its function.
• 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-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.
• Immobilised enzymes - Enzymes which are attached to an inert, insoluble material over which the substrate passes and the reaction takes place
• 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.
• Non-competitive inhibitors - An inhibitor which binds to a different part of an enzyme known as the allosteric site and prevents the enzyme from functioning.
• 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.
• extracellular enzyme - An enzyme that is secreted by cells and functions outside of cells, e.g. amylase.
• Metabolism is the sum of all the enzyme controlled chemical reactions taking place in a cell.
• Anabolic and catabolic reactions are the two main types of reactions that make up metabolism.
• Anabolism is a set of metabolic pathways that synthesise complex molecules from smaller, simpler molecules.
• Catabolism is a set of metabolic pathways that breakdown complex molecules into smaller, simpler molecules.
• An enzyme is a biological catalyst used to speed up the rate of intracellular and extracellular biochemical reactions and is not used up or permanently altered.
• The 3D structure of each enzyme (including the active site) is unique due to the presence of different side chains and branches.
• The minimum amount of energy required for a reaction to take place is defined as activation energy.
• Only specific substrates complementary to the active site can bind.
• The induced-fit hypothesis is a model of enzyme action which states that once a specific substrate binds to the active site, the enzyme undergoes subtle conformational changes, putting a strain on the substrate, lowering the activation energy for the reaction.
• Immobilised enzymes are enzymes which are attached to an inert, insoluble material over which the substrate passes and the reaction takes place.
• Catalysis is an increase in the rate of a chemical reaction using a catalyst (such as an enzyme), which lowers the activation energy of the reaction.
• In the 'lock and key' model, the product(s) are released from the active site, leaving the active site free to bind to another substrate.
• The 'lock and key' model describes how substrate(s) and the active site of the enzyme come into contact, bind, form an enzyme-substrate complex, and undergo a reaction, resulting in product(s) formed in an enzyme-product complex.
• Non-competitive inhibition is permanent.
• An example of an application of immobilised enzymes is in biosensors.
• The substrate cannot bind and the enzyme is inhibited.
• Immobilised enzymes are important in industrial processes as they enable enzymes to be reused, improve enzyme stability in variable/extreme temperatures and pH, and increase the efficiency of reactions.
• Increasing the substrate concentration will not overcome the effect of the non-competitive inhibitor.
• Increasing substrate concentration increases the rate of reaction.
• Once all active sites become full, the rate of reaction remains constant (graph plateaus).