Type of protein

• catalyse (speeds up) anabolic or catabolic

  • increases reaction rates

  • by lowering the activation energy

  • so the reaction can proceed at 37 degrees

• Highly specific

  • specific shape

  • puzzle shape

Substate

• the molecule the enzyme acts on

Active site

• region of the substate the enzyme attaches to

• complementary shapes

Lock and Key model

• enzyme is unchanged throughout (shape stays the same)

• enzyme acts like a key

• substrate is the lock

• once combined they form enzyme substrate complex

• reactions proceed, the products

• the enzyme remains unchanged throughout this process

Factors affecting enzyme activity

• enzyme concentration

  • higher enzyme concentration, faster the reaction

  • this is because there is plenty of enzyme molecules to attach to the substrate

• Substrate concentration

  • higher the substrate concentration, the faster the reaction until enzymes are saturated

  • this is due to all the molecules are saturated (all being used)

Factors Affecting enzyme activity

• removal of products

  • the more products removed, the faster the reaction

  • this is due to there being a greater chance of collisions between the enzyme and substrate without products getting in the way

• Temperature

  • the higher the temperature the faster the reaction until it reaches optimum (best) temperature, the the reaction falls

  • heat is a form of energy that increases particles movement, therefore more heat

• pH

  • whether the reactions take place acidic, alkaline or neutral environment

  • each enzyme will have an optimum level of pH

  • ex. the stomach works best un an acidic or low pH environment

• Presence of cofactors and coenzymes

  • Cofactors are non-protein inorganic molecules such as ions which highly bind to the active site to change the shape so the enzyme can attach

  • coenzymes are non-protein organic molecules such as vitamins which loosely bind to the active site on the enzyme to change the shape to the enzyme can attach