factors affecting enzyme action

• how does temperature affect enzyme activity?

  - temperature rises, molecules have more kinetic energy

  - free molecules move around more quickly so collide more often

  - more molecules have sufficient energy to overcome the activation energy

  - more ESC
• what can happen to enzyme activity once past optimum temperature?

  - particles within a molecule vibrate more and disrupt the weak H-bonds

  - tertiary structure changes

  - active site changes shape

  - no ESC are formed

  - enzyme is denatured
• how can significant changes in pH concentration affect enzyme activity?

  - disrupting ionic bonds that maintain the tertiary structure

  - active site changes shape

  - no ESC are formed

  - enzyme is denatured
• what else can significant changes in pH concentration do?

  - altering the charge of amino acids that form the active site - making it difficult for the substrate to bind

  - no ESC are formed
• what happens when substrate concentration is low?

  - fewer successful collisions

  - not all the active sites are occupied at any one time

  - fewer ESCs formed
• what happens when substrate concentration is high?

  - more successful collisions

  - all the active sites are occupied at anyone time

  - more ESCs

  - enzyme is working as fast as possible
• what happens when substrate concentration is excess?


  - all the active sites are occupied at any one time so an increase in substrate concentration has no effect on the rate of reaction
• what happens if there is an excess of substrate and an increase in enzyme concentration?

  - it leads to a proportionate increase in rate of reaction
• Why does this happen?

  - there is more substrate than the enzymes active sites can bind with

  - will only work up to a certain concentration, where the enzyme concentration is no longer the limiting factor
• what do inhibitors do?

  - prevent enzymes forming ESCs

  - slow down the rate of reaction
• what do competitive inhibitors do?

  - similar shape to the substrate

  - prevents access to to the active site

  - fewer enzyme - substrate complexes formed

  - reversible
• how to overcome the effect of competitive inhibitor?

  - increase the substrate concentration

  - more successful concentrations

  - as more will bind to the active site in preference to the inhibitor
• what do non-competitive inhibitors do?

  - no similarity to the substrate shape

  - binds to the enzyme at the allosteric site

  - irreversible - permanently alters enzymes tertiary structure and shape of active site
• can increasing substrate concentration overcome noncompetitive inhibition?


  - no