enzymes

• a catalyst is a substance which increases the speed of a reaction without being used up
• enzymes are all LARGE PROTEINS! all proteins are made of chains of amino acids which are folded into unique shapes
• • every enzyme has an ACTIVE SITE with a unique shape that fits onto the substance involved
  • only catalyse one specific reactions
  • bc substrate has to FIT into its active site
  • active site changes shape slightly as substrate binds to get an induced fit to subtrate
• | enzymes need the right temp & pH

  • changing temp changes rate
  • higher temp increases rate until it gets too hot which denatures the active site usually at 45 degrees
  • pH also affects enzymes as it can also denature the active site
  • often optimum at 7
  • pepsin doesnt- to break down proteins in the stomach, it works best in pH2 in acidic conditions