Enzymes AS Unit 1 Introduction Enzymes as Catalysts

Learning Objectives Describe the structure of enzymes Describe the structure of enzymes Explain how enzymes act as catalysts Explain how enzymes act as catalysts Understand the effects of pH, and temperature on enzymes Understand the effects of pH, and temperature on enzymes

Properties of Enzymes Enzymes are large protein molecules Enzymes are large protein molecules They act as biological catalysts They act as biological catalysts They are globular proteins, with a hydrophobic core and hydrophilic outer amino-acids, so they are usually soluble They are globular proteins, with a hydrophobic core and hydrophilic outer amino-acids, so they are usually soluble They have a complex tertiary structure which causes them the to fold in a very specific way to create an active site They have a complex tertiary structure which causes them the to fold in a very specific way to create an active site

Enzyme Specificity Enzymes react with chemicals either to build up longer polymer chains or to break down long chains into small sub units Enzymes react with chemicals either to build up longer polymer chains or to break down long chains into small sub units The chemicals which an enzyme reacts with are called substrates The chemicals which an enzyme reacts with are called substrates Every enzymes is specific to one substrate only Every enzymes is specific to one substrate only

Builder or Breaker

Enzymes as Catalysts A catalysts speeds up the rate of a reaction with out being used up in the process A catalysts speeds up the rate of a reaction with out being used up in the process Enzymes also reduce the activation energy required for the reaction to take place Enzymes also reduce the activation energy required for the reaction to take place Enzymes do this by binding to the substrate at a special active site in the enzyme Enzymes do this by binding to the substrate at a special active site in the enzyme

Activation Energy Activation energy is the amount of energy required for the reaction to take place Activation energy is the amount of energy required for the reaction to take place Enzymes reduce this by either bringing substrates together or helping them to break apart Enzymes reduce this by either bringing substrates together or helping them to break apart

Lock and Key Theory All enzymes have an active site All enzymes have an active site This is a special 3 dimensional arrangement of amino-acids which create a space in the enzyme where substrates can bond This is a special 3 dimensional arrangement of amino-acids which create a space in the enzyme where substrates can bond Only a specific enzyme can bind to this site Only a specific enzyme can bind to this site

Active Sites